science.sciencemag.org/content/370/6512/eabb8985/suppl/DC1

Supplementary Materials for

Vapor-assisted deposition of highly efficient, stable black-phase

FAPbI3 perovskite solar cells

Haizhou Lu, Yuhang Liu, Paramvir Ahlawat, Aditya Mishra, Wolfgang R. Tress, Felix T.

Eickemeyer, Yingguo Yang, Fan Fu, Zaiwei Wang, Claudia E. Avalos, Brian I. Carlsen, Anand

Agarwalla, Xin Zhang, Xiaoguo Li, Yiqiang Zhan*, Shaik M. Zakeeruddin, Lyndon Emsley,

Ursula Rothlisberger, Lirong Zheng*, Anders Hagfeldt*, Michael Grätzel*

*Corresponding author. Email: yqzhan@fudan.edu.cn (Y.Z.); lrzheng@fudan.edu.cn L.Z.); anders.hagfeldt@epfl.ch

(A.H.); michael.graetzel@epfl.ch (M.G.)

Published 2 October 2020, Science 370, eabb8985 (2020)

DOI: 10.1126/science.abb8985

This PDF file includes:

Materials and Methods

Supplementary Text

Figs. S1 to S27

Captions for Movies S1 to S7

References

Other Supplementary Material for this manuscript includes the following:

(available at science.sciencemag.org/content/370/6512/eabb8985/suppl/DC1)

Movies S1 to S7

2

Materials and Methods

Materials

Formamidinium iodide (FAI) and formamidinium thiocyanate (FASCN) were purchased

from Great Solar Australia Pty Ltd. Lead iodide (PbI2) and tin oxide (SnO2) colloid precursor were

purchased from Alfa Aesar. Bis(trifluoromethane)sulfonimide lithium salt (Li-TFSI) and 4-tert-

butyl-pyridine (tbp) were purchased from Sigma-Aldrich. Spiro-OMeTAD was purchased from

Xi’an Polymer Light Technology Corp. Methylamine thiocyanate (MASCN) was purchased from

Tokyo Chemical Industry Co., LTD. N, N-dimethylformamide (DMF), N-Methyl-2-Pyrrolidone

(NMP), chlorobenzene (CB), isopropanol (IPA), and acetonitrile (ACN) were purchased from

Acros Organics. All materials were used as received without further modifications.

Solar cell fabrication

SnO2 layer was spin-coated onto the cleaned ITO substrates from a diluted SnO2 nanoparticle

solution (2.67 wt%) at a spin speed of 4000 rpm for 30 s with additional post annealing at 150 ℃

for 30 mins (5). As fabricated SnO2 layer was treated with UV-ozone for 15 mins just before the

FAPbI3 perovskite layer deposition. The perovskite precursor solution was prepared by mixing

172 mg FAI and 461 mg PbI2 with 600 µL DMF and 100 µL NMP. The perovskite layer was

fabricated by spin coating 30 µL perovskite precursor solution on top of the SnO2 layer at a speed

of 5000 rpm for 30 s inside a dry air glovebox (relative humidity < 5%). At the time of 15 s to the

end, 200 µL CB was quickly dropped as an antisolvent. For the reference FAPbI3 perovskite, the

as fabricated film was annealed at 100 ℃ for 1 min and then at 150 ℃ for 20 mins. For the vapor-

treated perovskite, the as fabricated FAPbI3 perovskite film was firstly annealed at 100 ℃ for 1

min. Then, the perovskite film was put into MASCN/FASCN environment for 5 s until it turns to

black. Finally, the perovskite film was further annealed at 150 ℃ for 20 mins. MASCN/FASCN

solution (3 mg/mL in IPA) was dipped onto a metal sheet and annealed at 100 ℃ for 1 min to

generate the vapor environment. After cooling down the perovskite film on the bench, choline

chloride solution (1mg/mL in IPA) was used to passivate the surface. Then, doped Spiro-OMeTAD

solution (72.3 mg/mL in chlorobenzene) was spin-coated on top of the perovskite layer at a speed

of 3000 rpm for 30 s. For 1 mL Spiro-OMeTAD solution, 17.5 µL Li-TFSI (520 mg/mL in

acetonitrile), 29 µL tbp and 2.5 mg ADAHI (detailed synthesis can be found in reference (39))

were added as dopants. Finally, an 80-nm gold layer was evaporated under high vacuum at a rate

of 0.01 nm/s.

Photovoltaic device testing

Photocurrent density-voltage (J-V) curves were measured using a Keithley 2400 source meter

together with a Xenon arc lamp based solar simulator. The solar simulator was calibrated to AM

1.5G illumination (100 mW/cm2) using a calibrated reference silicon solar cell. All J-V

measurements were performed under a constant scan speed of 10 mV/s inside a box purged with

cool dry air. The photovoltaic data were collected without any device preconditioning. A black,

non-reflective metal mask with an aperture area of 0.16 cm2 was used to cover the active area (~

0.27 cm2) of the device to avoid the artefacts produced by scattered light.

Incident photon-to-electron conversion efficiency (IPCE) measurement

IPCE was measured with a commercial apparatus (Arkeo-Ariadne, Cicci Research s.r.l) based

on a 300 W Xenon lamp. It was recorded as a function of wavelength under a constant white light

bias of approximately 5 mW/cm2 supplied by an array of white light emitting diodes. For all

3

measurements, a non-reflective metal mask with an aperture area of 0.16 cm2 was used to cover

the active area of the device to avoid light scattering through the sides.

External quantum efficiency of the electroluminescence (EQEEL) measurement

To measure the EQEEL, the emitted photon flux was recorded using a calibrated, large area

(1cm2) Si photodiode (Hamamatsu S1227-1010BQ) by applying different bias voltage or current

to the FAPbI3 PSC device with a Bio-logic SP300 potentiostat. All measurements were performed

in the ambient environment (relative humidity is ~30% and environmental temperature is ~23 ℃).

Stability measurement

Stability measurements were performed with a Biologic MPG2 potentiostat under a LED lamp

which was adjusted to the AM 1.5G illumination (100 mW/cm2). The devices (unencapsulated)

were masked (0.16 cm2) and put inside a homemade sample holder purged with nitrogen during

the whole measurements. The devices were measured with a maximum power point (MPP)

tracking routine under continuous one sun illumination. The MPP measurement was updated every

60 s by a standard perturb and observe method. The temperature of the device was controlled at

25 ℃ by a Peltier element in direct contact with the devices. The temperature was measured with

a surface thermometer located between the Peltier element and the device. Both reverse and

forward scanned J-V curves were recorded every 30 mins.

Characterization

Scanning electron microscopy (SEM) images were taken using a high-resolution scanning

microscope (ZEISS Merlin). The X-ray diffraction patterns were performed using Cu Kα radiation

as the X-ray source. Ultraviolet-visible (UV-vis) spectra were measured with a Varian Cary 5.

Photoluminescence (PL) spectra were recorded using Fluorolog 322 (Horiba Jobin Ybon Ltd) with

an excitation wavelength at 460 nm. Time-resolved PL (TRPL) measurement was performed

using Fluorolog 322 spectrofluorometer (Horiba Jobin Yvon, Ltd). A NanoLED-637L (Horiba)

laser diode (637 nm) was used for excitation. The samples were mounted at 60° and the emission

collected at 90° from the incident beam path. The detection monochromator was set to 650 nm and

the PL was recorded using a picosecond photodetection module (TBX-04, Horiba Scientific).

Surface roughness measurements were taken with a Cypher S atomic force microscope (AFM)

from Asylum Research under ambient conditions. An Olympus AC240-TS tip was employed, and

the system was operated under tapping mode.

Solid-state NMR measurement

Room-temperature 1H (900 MHz) and 14N (65.04 MHz) NMR spectra were recorded on a

Bruker Avance Neo 21.1 T spectrometer equipped with a 3.2 mm low-temperature CPMAS probe. 133Cs shifts were referenced to 1 M aqueous solution of CsCl, using solid CsI (δ=271.05 ppm) as

a secondary reference. 1H chemical shifts were referenced to solid adamantane (δH=1.91 ppm). 14N

chemical shifts were referenced to solid adamantane (δH= 0 ppm). Quantitative echo-detected 1H

spectra used a recycle delay of 2 to 50 s. Peak widths were fitted in Topspin 3.2 and the

uncertainties were given at one standard deviation.

Computational method

We constructed a large super-cell of δ-phase FAPbI3 with 28800 atoms (2400 stoichiometric

units of FAPbI3). To perform molecular dynamics (MD) simulations of FAPbI3, we followed a

4

similar procedure as used in our previous work (50). Polytypes play an important role in

crystallization of FAPbI3. Therefore, we also upgraded the previously used force field to be able

to simulate all the experimentally known polytypes (2H, 4H, 6H and 3C) of FAPbI3. At first, we

equilibrated this super-cell by performing 10 ns variable-cell isothermal-isobaric simulations at

370 K. Next, we exposed this super-cell to MA+ and SCN- ions (fig. S6). With this set-up, we

again performed an equilibrium run for 2 ns in isothermal-isobaric ensemble at 370 K with a force

field for SCN- ions available from literature (51). Interaction parameters between different

heterogeneous species were calculated with mixing rules. All production runs were performed in

isothermal-isobaric ensemble ranging from 20-100 ns. All simulations were performed with the

Large-Scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) code (31 Mar 2017)

(52). We used a 1.0 nm cutoff for nonbonded interactions, SHAKE (53) for constraints and

particle-particle-particle-mesh Ewald for electrostatic interactions. We used a velocity rescaling

thermostat (54) with a relaxation time of 0.1 ps and a Parrinello-Rahman barostat (55) to keep the

pressure at atmospheric pressure with a relaxation time of 10 ps.

DFT calculations of 4H and 2H polytype with SCN-

First, we replaced up to 50% I- with SCN- ions in the 2H (δ-phase) and 4H-FAPbI3 crystal

structures (56). Then, we performed variable cell first-principles density functional theory (DFT)

calculations of these structures with Generalized Gradient Approximation (GGA) in the Perdew-

Burke-Ernzerhof formulation revised for solids (PBEsol) (57). We used Quantum Espresso (58)

with ultra-soft pseudo-potentials for valence-core electron interactions with a plane wave basis set

of 60 Ry kinetic energy cutoff and 420 Ry density cutoff. The Brillouin zone was sampled by a

2x2x2 k-points grid for 192 atoms supercell of 4H-FAPbI3 and equivalent of 2H structures. The

optimized structures are shown in the supplementary materials.

Details of the DFT calculations for the energy barrier

We first identified a possible phase transition pathway between δ and α-phases of FAPbI3. In

order to generate initial transition structures, we explored the phase space between δ and α-phases

of FAPbI3 with classical MD simulations at different temperatures and interpolated the coordinates

(Pb2+ and I-) along a path from face-sharing to edge-sharing to corner-sharing structures. We would

like to note that here we depicted only one possible transformation pathway (fig. S13), bur that the

system can also go through many different phase transition pathways. To calculate the potential

energy, landscape of this transition pathway we performed variable-cell enthalpic optimization for

each structure with first-principles DFT calculations. For DFT calculations, we used Quantum

Espresso (58) with ultra-soft pseudo-potentials for valence-core electron interactions with a plane

wave basis set of 60 Ry kinetic energy cut-off and 420 Ry density cut-off. All DFT calculations

for the energy barrier used Generalized Gradient Approximation (GGA) and Perdew-Burke-

Ernzerhof (PBE) (59) functional with D3-vdW (60) dispersion corrections. The Brillouin zone was

sampled by a 3×3×3 k-points grid for 96 atoms (2×2×2 supercell) supercell of α-FAPbI3 and

equivalent for other structures. The eanergetic profile along the hypothetical pathway (fig. S13)

provided a first rough estimate of the possible height of the energy barrier involved in the transition

between the two phses, however, the real physical transition might occur along a different path

and the calculations along the sequence of structures (fig. S13) did not include the transition states

involved in going from one intermediate to the next one that might involve even higher energy

points.

5

Ab-initio MD of SCN- vapor on δ-phase

An initial configuration, as depicted in fig. S8 was created by putting 14 SCN- ions in a box

with a 192 atoms supercell of δ-phase FAPbI3. Constant temperature and constant volume (NVT)

Born-Oppenheimer MD (BOMD) simulations were performed with the CP2K package (61, 62).

We used a time step of 1fs and a Nose-Hoover chain (63) for temperature control. We performed

BOMD simulations at two different temperatures: 300 and 400 K. All simulations used DFT at the

PBE+D3 (59, 60) level with double-zeta basis sets (DZVP-MOLOPT for Pb, I, S, C, N, H) (64)

and Goedecker-Teter-Hutter (GTH) pseudopotentials (65) with 560 Ry density cut-off.

Ab-initio MD of homogeneous mixture of ions

We performed constant temperature and constant pressure (NPT) simulations of a

homogeneous mixture of ions: 4 Pb2+, 9 I-, 9 SCN-, 5FA+ and 5MA+ as depicted in fig. S9. We

used a similar quantum-mechanical set-up for the BOMD as described in the section above. A

Nose-Hoover chain (63) was used for controlling temperature and the barostat by Martyna et al.

(66) was used for pressure control. We performed simulations at two different temperatures: 350

and 400 K at a pressure of 1atm.

Two-dimensional grazing-incidence XRD (2D-GIXRD) measurement

The 2D-GIXRD measurements were performed at the BL14B1 beamline of the Shanghai

Synchrotron Radiation Facility (SSRF) using X-ray with a wavelength of 0.6887 Å. 2D-GIXRD

patterns were acquired by a MarCCD mounted vertically at a distance of ~632 mm from the sample

with grazing incidence angles of 0.05°, 0.10° and 0.40°, and the exposure time of 30 s.

Time-of-flight secondary ion mass spectrometry (ToF-SIMS) measurement

ToF-SIMS measurements were performed on a ToF-SIMS.5 instrument from IONTOF, Germany,

operated in spectral mode using a 25 keV Bi3+ primary ion beam with an ion current of 0.57 pA.

A mass resolving power in the range of 7000-10000 m/Δm was reached. For depth profiling, a 500

eV Cs+ sputter beam with a current of 25.36 nA was used to remove the material layer-by-layer in

interlaced mode from a raster area of 300 μm × 300 μm. Both positive and negative ions were

collected for depth profile analysis. The mass-spectrometry was performed on an area of 100 μm

× 100 μm in the center of the sputter crater.

Supplementary Text

Note 1. Calculations of MA amount

x = MA integral / # MA[1H]

y = FA integral / # FA[1H]

MA amount = x/y * FA amount

x = 2.0817/6 = 0.34695, y = 97.9183/5 = 19.58366

MA amount = 0.01771630022 * FA amount

MA amount = 1.77 % of FA amount

Note 2. Determination of the Urbach energy 𝐸𝑢, the radiative limit 𝑉oc,rad, the measured Voc and the effect of temperature.

For the determination of 𝑉oc,rad and 𝐸𝑢 , we follow the work of Tress et al. (41). From the electroluminescence 𝐽em(V) (Fig. 4E) at voltage V = 1.0 V, we calculated the spectral shape of

6

the absorptance 𝑎(𝐸)~𝐽𝑒𝑚(𝑉)

𝛷𝐵𝐵(𝐸), where 𝛷𝐵𝐵(𝐸) =

1

4𝜋2ℏ3𝑐2𝐸2

exp (𝐸

𝑘𝐵𝑇−1)

is the spectral photon flux of

the black body radiation and the temperature T is 23 °C (temperature of the EL measurements).

We recalibrated the absorptance with the above bandgap IPCE at 760 nm (1.63 eV) from Fig. 4C

(IPCE (1.63 eV) = 87.7%). This yields the absorptance spectrum as shown in fig. S20. The

exponential fit between 1.4 and 1.5 eV results in the Urbach energy 𝐸𝑢 = 13.9 meV. From 𝑎(𝐸) we calculated the emitted photon flux in thermal equilibrium 𝐽𝑒𝑚,0 = 𝑒 ∫ 𝑎(𝐸)𝛷𝐵𝐵(𝐸)𝑑𝐸 and

from this the radiative limit open-circuit voltage 𝑉oc,rad = 𝑘𝐵𝑇 𝑒⁄ ln(𝐽𝑝ℎ 𝐽𝑒𝑚,0 + 1⁄ ) = 1.254 V ,

where 𝐽𝑝ℎ = 25 mA/cm2 is the short circuit current under one sun illumination. For this calculation

we used the temperature T = 20.1°C, which is the temperature of the device with the highest Voc

(1.19 V) measured under cooling air flow (Fig. 4D). In fig. S21, A and B, we showed how the

temperature affected the calculated Urbach energy and 𝑉oc,rad, respectively. The Urbach energy determined from the EL as explained above varies from 13.7 meV at 15 °C to 14.1 meV at 30 °C,

which demonstrates that it has a very small temperature effect. As for the temperature effect on

𝑉oc,rad, we calculated 𝑉oc,rad = 1.259 V at 15 °C and 𝑉oc,rad = 1.245 V at 30 °C, i.e. 𝑉oc,rad changes 1 mV/°C. The expected 𝑉oc,exp = 𝑉oc,rad + ∆𝑉oc [ ∆𝑉oc = 𝑘𝑇 𝑞⁄ ln(𝜂𝑒𝑥𝑡) ] has a temperature

dependence as shown in fig. S21C.

We did our J-V measurements under two conditions: 20. 1 °C (for air flow cooled samples) and

25 °C (for non-air flow cooled samples). The measured Voc is 1.19 V at 20.1 °C and 1.18 V at 25

°C without using a mask, and a relevant 𝑉oc,exp is calculated to be 1.185 V and 1.179 V, and ∆𝑉𝑜𝑐

is 69.0 mV and 70.2 mV, respectively. We note that the measured EQEEL is underestimated, as a

considerable number of emitted photons are trapped inside the glass layer. Thus, the difference

between the measured and predicted values could be due to the inaccuracy of EQEEL

measurements.

Lastly, we determined the measured Voc of 1.18 ± 0.005 V for the mask-free conditions at a

temperature of 25 °C (error is given from a 5 °C temperature range).

7

Fig. S1. XRD patterns of FAPbI3 perovskite films after MASCN vapor treatment for

different time from 0 to 100 s.

5 10 15 20 25 30 35 40 45 50 55 60 65

100 seconds treatment

10 seconds treatment

5 seconds treatment

2 seconds treatment

untreated

Norm

alis

ed I

nte

nsi

ty

2q (o)

d

d

8

Fig. S2. 2D-GIXRD measurements of the FAPbI3 films. 2D-GIXRD patterns collected at X-ray

incident angles of (a) 0.05°, (b) 0.10° and (c) 0.40° from the reference FAPbI3 perovskite film.

2D-GIXRD patterns collected at X-ray incident angles of (d) 0.05°, (e) 0.10° and (f) 0.40° from

the MASCN vapor-treated FAPbI3 perovskite film. GIXRD spectra around the perovskite (001)

diffraction peaks at incident angles of 0.05°, 0.10° and 0.40° for (g) the MASCN-vapor treated

FAPbI3 perovskite films and (h) the reference FAPbI3 perovskite films. GIXRD spectra around the

perovskite (001) diffraction peaks at incident angles of (i) 0.05° and (j) 0.40° for both the MASCN

vapor-treated and reference FAPbI3 perovskite films.

9

Fig. S3. Characterization of the FAPbI3 films. Atomic force microscopy (AFM) images of (a)

reference FAPbI3 film and (b) MASCN vapor-treated FAPbI3 film. Top-view SEM images of δ-

phase FAPbI3 perovskite films before vapor treatment: (c) scale bar is 200 nm and (d) scale bar is

1 µm.

10

Fig. S4. ToF-SIMS depth profiles. (a) MA+ and FA+ contents of the vapor-treated FAPbI3, 1 mol

% MA+-doped FAPbI3 reference and background signal from pure FAPbI3 reference films. (b)

PbI2- and SCN- contents of the vapor-treated FAPbI3 film. The sputtering time of 100 s corresponds

to a distance of ~100 nm.

100

101

102

103

104

0 20 40 60 80 100

100

101

102

103

104[PbI2]

-

Inte

nsity (

counts

)

13FA+ ([13CH(NH2)2]+) (vapor-treated FAPbI3)

Perovskite

background signal from pure FAPbI3 reference

MA+ ([CH3NH3]+) (vapor-treated FAPbI3)

MA+ ([CH3NH3]+) (1 mol % MA+ in FAPbI3 reference)

(vapor-treated FAPbI3)

(vapor-treated FAPbI3)

(vapor-treated FAPbI3)[SCN]-

Inte

nsity (

counts

)

Sputter time (s)

[34SCN]-

11

Fig. S5. 1H-1H spin diffusion measurements at 21.1 T, 20 kHz MAS and 298 K at 1 s of

mixing time.

12

Fig. S6. Simulation set-up: δ-FAPbI3 with MA+ and SCN- on top. This image was generated

with Visual Molecular Dynamics (VMD). Pb-I octahedra are shown with golden color with iodide

as orange balls at the corners of the octahedra. FA+, MA+, and SCN- ions are shown with ball and

sticks representation. Nitrogen is dark blue, carbon is light blue, hydrogen is white, and sulfur is

yellow.

13

Fig. S7. Top view of the adsorption of SCN- ions on top of δ-FAPbI3. (a) Top view of the

simulations. (b) A zoomed-in version of a small part of the top view to clearly show the adsorption

of SCN- ions on top. These images were generated with VMD. The color coding is the same as in

fig. S6.

14

Fig. S8. Configuration for the δ-FAPbI3 with SCN- on top. (a) The starting configuration (at

t=0) and (b) the configuration at t = ~10 ps for the δ-FAPbI3 with SCN- on top. We show the

dimensions of the supercell to display the empty space used to treat the SCN- ions as vapor between

periodic slabs. Pb2+ ions and octahedron are shown with golden colour with iodide as pink balls.

FA+ and SCN- ions are shown with ball and sticks representation. The color coding is the same as

in Fig. S6.

15

Fig. S9. The formation of Pb-I-SCN octahedra and the radial distribution. (a) The formation

of Pb-I-SCN octahedral during ab-initio MD. Pb2+ ions and octahedron are shown with golden

colour with iodide as orange balls. FA+, MA+, and SCN- ions are shown with ball and sticks

representation. The color coding is the same as in fig. S6. (a). (b)The radial distribution function

g(r) between the sulfur atoms of SCN- and Pb2+ over the full ab-initio MD trajectory.

16

Fig. S10. A zoomed-in view of the final configuration of corner-sharing structures on the

interface. This image was generated with VMD. The color coding is the same as in fig. S6.

17

Fig. S11. Illustration of a possible phase transition path induced by SCN- anions. (a) δ-phase

FAPbI3 structure. The mixtures of δ and α-phases of FAPbI3 with the increasing number of corner-

sharing structures from (b) to (e). (f) α-phase FAPbI3 structure. SCN- ions are adsorbed on the top

of the respective structures. Pb2+ octahedra are portrayed with light blue colour with iodide as pink

balls on corners. FA+ and SCN- ions are represented with ball and sticks representation. The color

coding is the same as in fig. S6. All the images were generated with the VESTA software.

18

Fig. S12. Characterization of the FASCN vapor-treated FAPbI3 films. (a) XRD patterns of

the reference and FASCN vapor-treated FAPbI3 films annealed at 100 °C (inserted are the

pictures of corresponding FAPbI3 films after annealing). (b) J-V curve of one FASCN-treated

FAPbI3-based solar cell device.

19

Fig. S13. A possible transition pathway and corresponding activation barrier: Illustration of

a possible phase transition pathway between δ and α-phases FAPbI3. Each point on the energy

plot represent a different optimized structure along the path. A Gaussian fit of these points is

included as guide to the eyes. For better visualization of the pathway, we have illustrated some of

the intermediary phases. Pb-I octahedra are represented with light green colour with iodide on

corners with pink balls. FA+ cations are shown with ball and sticks representation. The color coding

is the same as in fig. S6. All images were generated with the VESTA software.

20

Fig. S14. Cross sectional scanning electron microscopy (SEM) image of a complete solar

cell device using glass/ITO/SnO2/FAPbI3/Spiro-OMeTAD/Au structure. The thicknesses of

SnO2, FAPbI3, Spiro-OMeTAD are about 20 nm, 480 nm and 200 nm, respectively.

21

Fig. S15. Statistic distributions of PV metrics, including (a) Jsc, (b) Voc, (c) FF and (d) PCE

for the MASCN vapor-treated FAPbI3 based PSCs.

22

Fig. S16. PV performance of the vapor-treated FAPbI3 PSCs. J-V curves measured for one

stressed FAPbI3-based PSC (a) in IMT and (b) in our lab. Measurements under MPP tracking

conditions for one stressed FAPbI3-based PSC (c) in IMT and (d) in our lab.

23

Fig. S17. J-V curves of one reference FAPbI3-based PSC under both forward and reverse

scan directions.

0.0 0.2 0.4 0.6 0.8 1.0 1.2

0

5

10

15

20

25

PCE = 16.31%

Forward scan

Reverse scan

Cu

rren

t d

ensi

ty (

mA

/cm

2)

Voltage (V)

PCE = 17.95%

24

Fig. S18. Steady state power output for one of the MASCN-treated FAPbI3-based PSCs at

MPP condition under one sun condition for 60 s.

0 10 20 30 40 50 60

0

5

10

15

20

25

PC

E (

%)

Time (s)

MPP tracking

25

Fig. S19. Voc as a function of time for 350 s for one of the MASCN-treated FAPbI3-based

PSCs under 0.9 sun illumination at room temperature.

0 50 100 150 200 250 300 350

1.00

1.04

1.08

1.12

1.16

VOC

Vo

lta

ge

(V

)

Time (s)

26

Fig. S20. Absorptance and exponential fit to determine the Urbach energy. For comparison

the EL spectrum from Fig. 4E and the spectral photon flux of the black body radiation at 23 °C

are shown.

27

Fig. S21. Theoretical calculations. (a) Urbach energy Eu , (b) radiative limit Voc , and (c) expected

Voc as a function of temperature calculated from the EL curve shown in fig. S20. The stars in (c)

indicate the Voc of measured devices.

28

Fig. S22. Tauc plot resulting in a 1.52 eV bandgap for the MASCN-treated FAPbI3 films.

1.46 1.48 1.50 1.52 1.54 1.56 1.58 1.60 1.62 1.64

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

(ahn)2

Energy (hn)

29

Fig. S23. TRPL measurements of the reference and the MASCN vapor-treated FAPbI3

films.

0 1000 2000 3000

10-3

10-2

10-1

100

Re

lative

in

ten

sity (

a.u

.)

Time (ns)

Treated FAPbI3 tavg=299.3 ns

Reference FAPbI3 tavg=79.8 ns

30

Fig. S24. Wall-plug efficiency of the MASCN-treated FAPbI3-based PSC devices as a

function of bias voltage from 0 to 2V.

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0

0

2

4

6

8

Wal

l-plu

g e

ffic

iency

(%

)

Voltage (V)

31

Fig. S25. EQEEL of the MASCN-treated FAPbI3-based PSC devices as a function of the

current density from 0 to 300 mA/cm2.

0 50 100 150 200 250 300

0

2

4

6

8

10

EQ

EE

L (

%)

Current density (mA/cm2)

32

Fig. S26. XRD patterns of the FAPbI3 films. (a) MASCN-treated FAPbI3 films annealed at 85

℃ under N2 for 100, 300 and 500 hours. (b) Reference FAPbI3 films annealed at 85 ℃ under N2 for 0 and 500 hours.

33

Fig. S27. J-V curves of the fresh FAPbI3-based PSCs and the FAPbI3-based PSCs after

2500 hours storage in a dry box.

0.0 0.2 0.4 0.6 0.8 1.0 1.2

0

5

10

15

20

25

Cu

rren

t d

ensi

ty (

mA

/cm

2)

Voltage (V)

Reverse scan of the device after 2500 hours

Forward scan of the device after 2500 hours

Reverse scan of the initial device

Forward scan of the initial device

34

Movie S1. The behavior of SCN- ions after addition of MASCN on top of δ-FAPbI3. We show

SCN- ions in balls and sticks representation: sulfur as yellow, carbon as light and nitrogen as blue

colored balls. MA+ ions are omitted for the sake for clarity. The Pb-I octahedra of δ-FAPbI3 are

shown with light-grey color with iodide as pink colored balls. FA+ ions are not shown for better

visualization.

Movie S2. A top view of the simulation showing that many SCN- ions get adsorbed on the

interface by replacing the iodide ions.

Movie S3. A full simulation of adding MASCN on top of δ-FAPbI3. Pb-I octahedra in δ-FAPbI3

are shown with golden color with iodide on corners as pink balls. FA+ ions shown with light blue

color, can be seen around face-sharing Pb-I octahedra. MA+ and SCN- ions are shown with balls

and sticks representation: sulfur with yellow color, carbon with light blue color, nitrogen with blue

color and hydrogen with white color.

Movie S4. Behavior of MA+ ions after addition of MASCN on top of δ-FAPbI3. We show MA+

ions in green color, SCN- ions are omitted for the sake of clarity. The Pb-I octahedra of δ-FAPbI3

are shown with light-grey color with iodide as pink colored balls. FA+ ions are not shown to better

visualize the diffusion of MA+ ions.

Movie S5. The transformation of face-sharing octahedra to corner-sharing octahedra on the

top surface layer of δ-FAPbI3. Here we show a part of the simulation box, mainly to clearly

visualize the transformation by the strongly coordinated SCN- ions on the top surface layer. Pb-I

octahedra are represented in golden color with iodide in corners as pink balls. SCN- ions are shown

with balls and sticks configuration: sulfur with yellow color, carbon with light blue color, and

nitrogen atoms with blue balls. SCN- coordinating octahedra are shown with red color for better

view.

Movie S6. The formation of different kinds of corner-sharing structures on top of δ-FAPbI3

after loading the MASCN.

Movie S7. The formation of polytypes through the interaction with SCN- ions.

35

References and Notes

1. W. Nie, H. Tsai, R. Asadpour, J.-C. Blancon, A. J. Neukirch, G. Gupta, J. J. Crochet, M.

Chhowalla, S. Tretiak, M. A. Alam, H.-L. Wang, A. D. Mohite, Solar cells. High-

efficiency solution-processed perovskite solar cells with millimeter-scale grains. Science

347, 522–525 (2015). doi:10.1126/science.aaa0472 Medline

2. M. Saliba, T. Matsui, K. Domanski, J.-Y. Seo, A. Ummadisingu, S. M. Zakeeruddin, J.-P.

Correa-Baena, W. R. Tress, A. Abate, A. Hagfeldt, M. Grätzel, Incorporation of rubidium

cations into perovskite solar cells improves photovoltaic performance. Science 354, 206–

209 (2016). doi:10.1126/science.aah5557 Medline

3. W. S. Yang, B.-W. Park, E. H. Jung, N. J. Jeon, Y. C. Kim, D. U. Lee, S. S. Shin, J. Seo, E. K.

Kim, J. H. Noh, S. I. Seok, Iodide management in formamidinium-lead-halide-based

perovskite layers for efficient solar cells. Science 356, 1376–1379 (2017).

doi:10.1126/science.aan2301 Medline

4. S. H. Turren-Cruz, A. Hagfeldt, M. Saliba, Methylammonium-free, high-performance, and

stable perovskite solar cells on a planar architecture. Science 362, 449–453 (2018).

doi:10.1126/science.aat3583 Medline

5. Q. Jiang, Y. Zhao, X. Zhang, X. Yang, Y. Chen, Z. Chu, Q. Ye, X. Li, Z. Yin, J. You, Surface

passivation of perovskite film for efficient solar cells. Nat. Photonics 13, 460–466

(2019). doi:10.1038/s41566-019-0398-2

6. E. H. Jung, N. J. Jeon, E. Y. Park, C. S. Moon, T. J. Shin, T.-Y. Yang, J. H. Noh, J. Seo,

Efficient, stable and scalable perovskite solar cells using poly(3-hexylthiophene). Nature

567, 511–515 (2019). doi:10.1038/s41586-019-1036-3 Medline

7. S. Bai, P. Da, C. Li, Z. Wang, Z. Yuan, F. Fu, M. Kawecki, X. Liu, N. Sakai, J. T.-W. Wang,

S. Huettner, S. Buecheler, M. Fahlman, F. Gao, H. J. Snaith, Planar perovskite solar cells

with long-term stability using ionic liquid additives. Nature 571, 245–250 (2019).

doi:10.1038/s41586-019-1357-2 Medline

8. S. Yang, S. Chen, E. Mosconi, Y. Fang, X. Xiao, C. Wang, Y. Zhou, Z. Yu, J. Zhao, Y. Gao,

F. De Angelis, J. Huang, Stabilizing halide perovskite surfaces for solar cell operation

with wide-bandgap lead oxysalts. Science 365, 473–478 (2019).

doi:10.1126/science.aax3294 Medline

9. Y. Wang, T. Wu, J. Barbaud, W. Kong, D. Cui, H. Chen, X. Yang, L. Han, Stabilizing

heterostructures of soft perovskite semiconductors. Science 365, 687–691 (2019).

doi:10.1126/science.aax8018 Medline

10. J. Tong, Z. Song, D. H. Kim, X. Chen, C. Chen, A. F. Palmstrom, P. F. Ndione, M. O. Reese,

S. P. Dunfield, O. G. Reid, J. Liu, F. Zhang, S. P. Harvey, Z. Li, S. T. Christensen, G.

Teeter, D. Zhao, M. M. Al-Jassim, M. F. A. M. van Hest, M. C. Beard, S. E. Shaheen, J.

J. Berry, Y. Yan, K. Zhu, Carrier lifetimes of >1 μs in Sn-Pb perovskites enable efficient

all-perovskite tandem solar cells. Science 364, 475–479 (2019).

doi:10.1126/science.aav7911 Medline

11. K. Lin, J. Xing, L. N. Quan, F. P. G. de Arquer, X. Gong, J. Lu, L. Xie, W. Zhao, D. Zhang,

C. Yan, W. Li, X. Liu, Y. Lu, J. Kirman, E. H. Sargent, Q. Xiong, Z. Wei, Perovskite

http://dx.doi.org/10.1126/science.aaa0472http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=25635093&dopt=Abstracthttp://dx.doi.org/10.1126/science.aah5557http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=27708053&dopt=Abstracthttp://dx.doi.org/10.1126/science.aan2301http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=28663498&dopt=Abstracthttp://dx.doi.org/10.1126/science.aat3583http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=30309904&dopt=Abstracthttp://dx.doi.org/10.1038/s41566-019-0398-2http://dx.doi.org/10.1038/s41586-019-1036-3http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=30918371&dopt=Abstracthttp://dx.doi.org/10.1038/s41586-019-1357-2http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=31292555&dopt=Abstracthttp://dx.doi.org/10.1126/science.aax3294http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=31371610&dopt=Abstracthttp://dx.doi.org/10.1126/science.aax8018http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=31416961&dopt=Abstracthttp://dx.doi.org/10.1126/science.aav7911http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=31000592&dopt=Abstract

36

light-emitting diodes with external quantum efficiency exceeding 20 per cent. Nature

562, 245–248 (2018). doi:10.1038/s41586-018-0575-3 Medline

12. Y. Cao, N. Wang, H. Tian, J. Guo, Y. Wei, H. Chen, Y. Miao, W. Zou, K. Pan, Y. He, H.

Cao, Y. Ke, M. Xu, Y. Wang, M. Yang, K. Du, Z. Fu, D. Kong, D. Dai, Y. Jin, G. Li, H.

Li, Q. Peng, J. Wang, W. Huang, Perovskite light-emitting diodes based on

spontaneously formed submicrometre-scale structures. Nature 562, 249–253 (2018).

doi:10.1038/s41586-018-0576-2 Medline

13. W. Xu, Q. Hu, S. Bai, C. Bao, Y. Miao, Z. Yuan, T. Borzda, A. J. Barker, E. Tyukalova, Z.

Hu, M. Kawecki, H. Wang, Z. Yan, X. Liu, X. Shi, K. Uvdal, M. Fahlman, W. Zhang, M.

Duchamp, J.-M. Liu, A. Petrozza, J. Wang, L.-M. Liu, W. Huang, F. Gao, Rational

molecular passivation for high-performance perovskite light-emitting diodes. Nat.

Photonics 13, 418–424 (2019). doi:10.1038/s41566-019-0390-x

14. B. Zhao, S. Bai, V. Kim, R. Lamboll, R. Shivanna, F. Auras, J. M. Richter, L. Yang, L. Dai,

M. Alsari, X.-J. She, L. Liang, J. Zhang, S. Lilliu, P. Gao, H. J. Snaith, J. Wang, N. C.

Greenham, R. H. Friend, D. Di, High-efficiency perovskite–polymer bulk heterostructure

light-emitting diodes. Nat. Photonics 12, 783–789 (2018). doi:10.1038/s41566-018-0283-

4

15. T. Matsushima, F. Bencheikh, T. Komino, M. R. Leyden, A. S. D. Sandanayaka, C. Qin, C.

Adachi, High performance from extraordinarily thick organic light-emitting diodes.

Nature 572, 502–506 (2019). doi:10.1038/s41586-019-1435-5 Medline

16. G. Xing, N. Mathews, S. S. Lim, N. Yantara, X. Liu, D. Sabba, M. Grätzel, S. Mhaisalkar, T.

C. Sum, Low-temperature solution-processed wavelength-tunable perovskites for lasing.

Nat. Mater. 13, 476–480 (2014). doi:10.1038/nmat3911 Medline

17. Y. C. Kim, K. H. Kim, D.-Y. Son, D.-N. Jeong, J.-Y. Seo, Y. S. Choi, I. T. Han, S. Y. Lee,

N.-G. Park, Printable organometallic perovskite enables large-area, low-dose X-ray

imaging. Nature 550, 87–91 (2017). doi:10.1038/nature24032 Medline

18. W. Pan, H. Wu, J. Luo, Z. Deng, C. Ge, C. Chen, X. Jiang, W.-J. Yin, G. Niu, L. Zhu, L.

Yin, Y. Zhou, Q. Xie, X. Ke, M. Sui, J. Tang, Cs2AgBiBr6 single-crystal X-ray detectors

with a low detection limit. Nat. Photonics 11, 726–732 (2017). doi:10.1038/s41566-017-

0012-4

19. A. Kojima, K. Teshima, Y. Shirai, T. Miyasaka, Organometal halide perovskites as visible-

light sensitizers for photovoltaic cells. J. Am. Chem. Soc. 131, 6050–6051 (2009).

doi:10.1021/ja809598r Medline

20. National Renewable Energy Laboratory, “Best research-cell efficiency chart” (2020);

www.nrel.gov/pv/cell-efficiency.html.

21. D. J. Kubicki, D. Prochowicz, A. Hofstetter, P. Péchy, S. M. Zakeeruddin, M. Grätzel, L.

Emsley, Cation dynamics in mixed-cation (MA)x(FA)1-xPbI3 hybrid perovskites from

solid-state NMR. J. Am. Chem. Soc. 139, 10055–10061 (2017). doi:10.1021/jacs.7b04930

Medline

22. D. J. Kubicki, D. Prochowicz, A. Hofstetter, M. Saski, P. Yadav, D. Bi, N. Pellet, J.

Lewiński, S. M. Zakeeruddin, M. Grätzel, L. Emsley, Formation of stable mixed

guanidinium-methylammonium phases with exceptionally long carrier lifetimes for high-

http://dx.doi.org/10.1038/s41586-018-0575-3http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=30305741&dopt=Abstracthttp://dx.doi.org/10.1038/s41586-018-0576-2http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=30305742&dopt=Abstracthttp://dx.doi.org/10.1038/s41566-019-0390-xhttp://dx.doi.org/10.1038/s41566-018-0283-4http://dx.doi.org/10.1038/s41566-018-0283-4http://dx.doi.org/10.1038/s41586-019-1435-5http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=31358964&dopt=Abstracthttp://dx.doi.org/10.1038/nmat3911http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=24633346&dopt=Abstracthttp://dx.doi.org/10.1038/nature24032http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=28980632&dopt=Abstracthttp://dx.doi.org/10.1038/s41566-017-0012-4http://dx.doi.org/10.1038/s41566-017-0012-4http://dx.doi.org/10.1021/ja809598rhttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=19366264&dopt=Abstracthttp://www.nrel.gov/pv/cell-efficiency.htmlhttp://dx.doi.org/10.1021/jacs.7b04930http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=28641413&dopt=Abstract

37

efficiency lead iodide-based perovskite photovoltaics. J. Am. Chem. Soc. 140, 3345–3351

(2018). doi:10.1021/jacs.7b12860 Medline

23. Z. Wang, Q. Lin, B. Wenger, M. G. Christoforo, Y.-H. Lin, M. T. Klug, M. B. Johnston, L.

M. Herz, H. J. Snaith, High irradiance performance of metal halide perovskites for

concentrator photovoltaics. Nat. Energy 3, 855–861 (2018). doi:10.1038/s41560-018-

0220-2

24. S. Draguta, O. Sharia, S. J. Yoon, M. C. Brennan, Y. V. Morozov, J. S. Manser, P. V. Kamat,

W. F. Schneider, M. Kuno, Rationalizing the light-induced phase separation of mixed

halide organic-inorganic perovskites. Nat. Commun. 8, 200 (2017). doi:10.1038/s41467-

017-00284-2 Medline

25. J. W. Lee, Z. Dai, T.-H. Han, C. Choi, S.-Y. Chang, S.-J. Lee, N. De Marco, H. Zhao, P. Sun,

Y. Huang, Y. Yang, 2D perovskite stabilized phase-pure formamidinium perovskite solar

cells. Nat. Commun. 9, 3021 (2018). doi:10.1038/s41467-018-05454-4 Medline

26. A. Swarnkar, A. R. Marshall, E. M. Sanehira, B. D. Chernomordik, D. T. Moore, J. A.

Christians, T. Chakrabarti, J. M. Luther, Quantum dot-induced phase stabilization of α-

CsPbI3 perovskite for high-efficiency photovoltaics. Science 354, 92–95 (2016).

doi:10.1126/science.aag2700 Medline

27. Y. Fu, T. Wu, J. Wang, J. Zhai, M. J. Shearer, Y. Zhao, R. J. Hamers, E. Kan, K. Deng, X.-

Y. Zhu, S. Jin, Stabilization of the Metastable Lead Iodide Perovskite Phase via Surface

Functionalization. Nano Lett. 17, 4405–4414 (2017). doi:10.1021/acs.nanolett.7b01500

Medline

28. J. Wang, S. Luo, Y. Lin, Y. Chen, Y. Deng, Z. Li, K. Meng, G. Chen, T. Huang, S. Xiao, H.

Huang, C. Zhou, L. Ding, J. He, J. Huang, Y. Yuan, Templated growth of oriented

layered hybrid perovskites on 3D-like perovskites. Nat. Commun. 11, 582 (2020).

doi:10.1038/s41467-019-13856-1 Medline

29. Y. Chen, Y. Lei, Y. Li, Y. Yu, J. Cai, M.-H. Chiu, R. Rao, Y. Gu, C. Wang, W. Choi, H. Hu,

C. Wang, Y. Li, J. Song, J. Zhang, B. Qi, M. Lin, Z. Zhang, A. E. Islam, B. Maruyama,

S. Dayeh, L.-J. Li, K. Yang, Y.-H. Lo, S. Xu, Strain engineering and epitaxial

stabilization of halide perovskites. Nature 577, 209–215 (2020). doi:10.1038/s41586-

019-1868-x Medline

30. I. Turkevych, S. Kazaoui, N. A. Belich, A. Y. Grishko, S. A. Fateev, A. A. Petrov, T. Urano,

S. Aramaki, S. Kosar, M. Kondo, E. A. Goodilin, M. Graetzel, A. B. Tarasov, Strategic

advantages of reactive polyiodide melts for scalable perovskite photovoltaics. Nat.

Nanotechnol. 14, 57–63 (2019). doi:10.1038/s41565-018-0304-y Medline

31. B. J. Foley, J. Girard, B. A. Sorenson, A. Z. Chen, J. Scott Niezgoda, M. R. Alpert, A. F.

Harper, D.-M. Smilgies, P. Clancy, W. A. Saidi, J. J. Choi, Controlling nucleation,

growth, and orientation of metal halide perovskite thin films with rationally selected

additives. J. Mater. Chem. 5, 113–123 (2017). doi:10.1039/C6TA07671H

32. M. Kim, D. Kim, Y. Wen, M. Kim, H. M. Jang, H. Li, L. Gu, B. Kang, High rate li-ion

batteries with cation-disordered cathodes. Joule 3, 1064–1079 (2019).

doi:10.1016/j.joule.2019.01.002

http://dx.doi.org/10.1021/jacs.7b12860http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=29429335&dopt=Abstracthttp://dx.doi.org/10.1038/s41560-018-0220-2http://dx.doi.org/10.1038/s41560-018-0220-2http://dx.doi.org/10.1038/s41467-017-00284-2http://dx.doi.org/10.1038/s41467-017-00284-2http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=28779144&dopt=Abstracthttp://dx.doi.org/10.1038/s41467-018-05454-4http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=30069012&dopt=Abstracthttp://dx.doi.org/10.1126/science.aag2700http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=27846497&dopt=Abstracthttp://dx.doi.org/10.1021/acs.nanolett.7b01500http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=28595016&dopt=Abstracthttp://dx.doi.org/10.1038/s41467-019-13856-1http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=31996680&dopt=Abstracthttp://dx.doi.org/10.1038/s41586-019-1868-xhttp://dx.doi.org/10.1038/s41586-019-1868-xhttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=31915395&dopt=Abstracthttp://dx.doi.org/10.1038/s41565-018-0304-yhttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=30478274&dopt=Abstracthttp://dx.doi.org/10.1039/C6TA07671Hhttp://dx.doi.org/10.1016/j.joule.2019.01.002

38

33. H. Min, M. Kim, S.-U. Lee, H. Kim, G. Kim, K. Choi, J. H. Lee, S. I. Seok, Efficient, stable

solar cells by using inherent bandgap of α-phase formamidinium lead iodide. Science

366, 749–753 (2019). doi:10.1126/science.aay7044 Medline

34. W. Xiang, Z. Wang, D. J. Kubicki, W. Tress, J. Luo, D. Prochowicz, S. Akin, L. Emsley, J.

Zhou, G. Dietler, M. Grätzel, A. Hagfeldt, Europium-doped CsPbI2Br for stable and

highly efficient inorganic perovskite solar cells. Joule 3, 205–214 (2019).

doi:10.1016/j.joule.2018.10.008

35. D. J. Kubicki, D. Prochowicz, A. Hofstetter, S. M. Zakeeruddin, M. Grätzel, L. Emsley,

Phase Segregation in Cs-, Rb- and K-Doped Mixed-Cation (MA)x(FA)1-xPbI3 Hybrid

Perovskites from Solid-State NMR. J. Am. Chem. Soc. 139, 14173–14180 (2017).

doi:10.1021/jacs.7b07223 Medline

36. D. J. Kubicki, D. Prochowicz, A. Hofstetter, S. M. Zakeeruddin, M. Grätzel, L. Emsley,

Phase segregation in potassium-doped lead halide perovskites from 39K solid-state NMR

at 21.1 T. J. Am. Chem. Soc. 140, 7232–7238 (2018). doi:10.1021/jacs.8b03191 Medline

37. B. A. Rosales, L. Men, S. D. Cady, M. P. Hanrahan, A. J. Rossini, J. Vela, Persistent dopants

and phase segregation in organolead mixed-halide perovskites. Chem. Mater. 28, 6848–

6859 (2016). doi:10.1021/acs.chemmater.6b01874

38. E. A. Alharbi, A. Y. Alyamani, D. J. Kubicki, A. R. Uhl, B. J. Walder, A. Q. Alanazi, J. Luo,

A. Burgos-Caminal, A. Albadri, H. Albrithen, M. H. Alotaibi, J.-E. Moser, S. M.

Zakeeruddin, F. Giordano, L. Emsley, M. Grätzel, Atomic-level passivation mechanism

of ammonium salts enabling highly efficient perovskite solar cells. Nat. Commun. 10,

3008 (2019). doi:10.1038/s41467-019-10985-5 Medline

39. M. Tavakoli, W. Tress, J. V. Milić, D. Kubicki, L. Emsley, M. Grätzel, Addition of

adamantylammonium iodide to hole transport layers enables highly efficient and

electroluminescent perovskite solar cells. Energy Environ. Sci. 11, 3310–3320 (2018).

doi:10.1039/C8EE02404A

40. P. Ahlawat, M. I. Dar, P. Piaggi, M. Grätzel, M. Parrinello, U. Rothlisberger, Atomistic

mechanism of the nucleation of methylammonium lead iodide perovskite from solution.

Chem. Mater. 32, 529–536 (2019). doi:10.1021/acs.chemmater.9b04259

41. W. Tress, N. Marinova, O. Inganäs, M. K. Nazeeruddin, S. M. Zakeeruddin, M. Graetzel,

Predicting the open-circuit voltage of CH3NH3PbI3 perovskite solar cells using

electroluminescence and photovoltaic quantum efficiency spectra: The role of radiative

and non-radiative recombination. Adv. Energy Mater. 5, 1400812 (2015).

doi:10.1002/aenm.201400812

42. G. E. Eperon, S. D. Stranks, C. Menelaou, M. B. Johnston, L. M. Herz, H. J. Snaith,

Formamidinium lead trihalide: A broadly tunable perovskite for efficient planar

heterojunction solar cells. Energy Environ. Sci. 7, 982–988 (2014).

doi:10.1039/c3ee43822h

43. M. A. Green, Y. Hishikawa, E. D. Dunlop, D. H. Levi, J. Hohl-Ebinger, A. W. Y. Ho-Baillie,

Solar cell efficiency tables (version 51). Prog. Photovolt. Res. Appl. 26, 3–12 (2018).

doi:10.1002/pip.2978

http://dx.doi.org/10.1126/science.aay7044http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=31699938&dopt=Abstracthttp://dx.doi.org/10.1016/j.joule.2018.10.008http://dx.doi.org/10.1021/jacs.7b07223http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=28892374&dopt=Abstracthttp://dx.doi.org/10.1021/jacs.8b03191http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=29779379&dopt=Abstracthttp://dx.doi.org/10.1021/acs.chemmater.6b01874http://dx.doi.org/10.1038/s41467-019-10985-5http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=31285432&dopt=Abstracthttp://dx.doi.org/10.1039/C8EE02404Ahttp://dx.doi.org/10.1021/acs.chemmater.9b04259http://dx.doi.org/10.1002/aenm.201400812http://dx.doi.org/10.1039/c3ee43822hhttp://dx.doi.org/10.1002/pip.2978

39

44. R. T. Ross, Some thermodynamics of photochemical systems. J. Chem. Phys. 46, 4590–4593

(1967). doi:10.1063/1.1840606

45. O. D. Miller, E. Yablonovitch, S. R. Kurtz, Strong Internal and External Luminescence as

Solar Cells Approach the Shockley–Queisser Limit. IEEE Journal of Photovoltaics 2,

303–311 (2012). doi:10.1109/JPHOTOV.2012.2198434

46. J. J. Yoo, S. Wieghold, M. C. Sponseller, M. R. Chua, S. N. Bertram, N. T. P. Hartono, J. S.

Tresback, E. C. Hansen, J.-P. Correa-Baena, V. Bulović, T. Buonassisi, S. S. Shin, M. G.

Bawendi, An interface stabilized perovskite solar cell with high stabilized efficiency and

low voltage loss. Energy Environ. Sci. 12, 2192–2199 (2019). doi:10.1039/C9EE00751B

47. D. Yang, R. Yang, K. Wang, C. Wu, X. Zhu, J. Feng, X. Ren, G. Fang, S. Priya, S. F. Liu,

High efficiency planar-type perovskite solar cells with negligible hysteresis using EDTA-

complexed SnO2. Nat. Commun. 9, 3239 (2018). doi:10.1038/s41467-018-05760-x

Medline

48. Q. Li, Y. Zhao, R. Fu, W. Zhou, Y. Zhao, X. Liu, D. Yu, Q. Zhao, Efficient perovskite solar

cells fabricated through CsCl-enhanced PbI2 precursor via sequential deposition. Adv.

Mater. 30, 1803095 (2018). doi:10.1002/adma.201803095

49. W. Tress, K. Domanski, B. Carlsen, A. Agarwalla, E. A. Alharbi, M. Graetzel, A. Hagfeldt,

Performance of perovskite solar cells under simulated temperature-illumination real-

world operating conditions. Nat. Energy 4, 568–574 (2019). doi:10.1038/s41560-019-

0400-8

50. L. Hong, J. V. Milić, P. Ahlawat, M. Mladenović, D. J. Kubicki, F. Jahanabkhshi, D. Ren, M.

C. Gélvez-Rueda, M. A. Ruiz-Preciado, A. Ummadisingu, Y. Liu, C. Tian, L. Pan, S. M.

Zakeeruddin, A. Hagfeldt, F. C. Grozema, U. Rothlisberger, L. Emsley, H. Han, M.

Graetzel, Guanine-stabilized formamidinium lead iodide perovskites. Angew. Chem. Int.

Ed. 59, 4691–4697 (2020). doi:10.1002/anie.201912051 Medline

51. G. Tesei, V. Aspelin, M. Lund, Specific cation effects on SCN– in bulk solution and at the

air-water interface. J. Phys. Chem. B 122, 5094–5105 (2018).

doi:10.1021/acs.jpcb.8b02303 Medline

52. S. Plimpton, Fast parallel algorithms for short-range molecular dynamics. J. Comput. Phys.

117, 1–19 (1995). doi:10.1006/jcph.1995.1039

53. J. Ryckaert, G. Ciccotti, H. J. C. Berendsen, Numerical integration of the cartesian equations

of motion of a system with constraints: Molecular dynamics of n-alkanes. J. Comput.

Phys. 23, 327–341 (1977). doi:10.1016/0021-9991(77)90098-5

54. G. Bussi, D. Donadio, M. Parrinello, Canonical sampling through velocity rescaling. J.

Chem. Phys. 126, 014101 (2007). doi:10.1063/1.2408420 Medline

55. M. Parrinello, A. Rahman, Polymorphic transitions in single crystals: A new molecular

dynamics method. J. Appl. Phys. 52, 7182–7190 (1981). doi:10.1063/1.328693

56. P. Gratia, I. Zimmermann, P. Schouwink, J.-H. Yum, J.-N. Audinot, K. Sivula, T. Wirtz, M.

K. Nazeeruddin, The many faces of mixed ion perovskites: Unraveling and understanding

the crystallization process. ACS Energy Lett. 2, 2686–2693 (2017).

doi:10.1021/acsenergylett.7b00981

http://dx.doi.org/10.1063/1.1840606http://dx.doi.org/10.1109/JPHOTOV.2012.2198434http://dx.doi.org/10.1039/C9EE00751Bhttp://dx.doi.org/10.1038/s41467-018-05760-xhttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=30104663&dopt=Abstracthttp://dx.doi.org/10.1002/adma.201803095http://dx.doi.org/10.1038/s41560-019-0400-8http://dx.doi.org/10.1038/s41560-019-0400-8http://dx.doi.org/10.1002/anie.201912051http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=31846190&dopt=Abstracthttp://dx.doi.org/10.1021/acs.jpcb.8b02303http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=29671594&dopt=Abstracthttp://dx.doi.org/10.1006/jcph.1995.1039http://dx.doi.org/10.1016/0021-9991(77)90098-5http://dx.doi.org/10.1063/1.2408420http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=17212484&dopt=Abstracthttp://dx.doi.org/10.1063/1.328693http://dx.doi.org/10.1021/acsenergylett.7b00981

40

57. J. P. Perdew, A. Ruzsinszky, G. I. Csonka, O. A. Vydrov, G. E. Scuseria, L. A. Constantin,

X. Zhou, K. Burke, Restoring the density-gradient expansion for exchange in solids and

surfaces. Phys. Rev. Lett. 100, 136406 (2008). doi:10.1103/PhysRevLett.100.136406

Medline

58. P. Giannozzi, S. Baroni, N. Bonini, M. Calandra, R. Car, C. Cavazzoni, D. Ceresoli, G. L.

Chiarotti, M. Cococcioni, I. Dabo, A. Dal Corso, S. de Gironcoli, S. Fabris, G. Fratesi, R.

Gebauer, U. Gerstmann, C. Gougoussis, A. Kokalj, M. Lazzeri, L. Martin-Samos, N.

Marzari, F. Mauri, R. Mazzarello, S. Paolini, A. Pasquarello, L. Paulatto, C. Sbraccia, S.

Scandolo, G. Sclauzero, A. P. Seitsonen, A. Smogunov, P. Umari, R. M. Wentzcovitch,

QUANTUM ESPRESSO: A modular and open-source software project for quantum

simulations of materials. J. Phys. Condens. Matter 21, 395502 (2009). doi:10.1088/0953-

8984/21/39/395502 Medline

59. J. P. Perdew, K. Burke, M. Ernzerhof, Generalized gradient approximation made simple.

Phys. Rev. Lett. 77, 3865–3868 (1996). doi:10.1103/PhysRevLett.77.3865 Medline

60. S. Grimme, Semiempirical GGA-type density functional constructed with a long-range

dispersion correction. J. Comput. Chem. 27, 1787–1799 (2006). doi:10.1002/jcc.20495

Medline

61. J. Hutter, M. Iannuzzi, F. Schiffmann, J. VandeVondele, CP2K: atomistic simulations of

condensed matter systems. Wiley Interdiscip. Rev. Comput. Mol. Sci. 4, 15–25 (2014).

doi:10.1002/wcms.1159

62. J. VandeVondele, M. Krack, F. Mohamed, M. Parrinello, T. Chassaing, J. Hutter, Quickstep:

Fast and accurate density functional calculations using a mixed Gaussian and plane

waves approach. Comput. Phys. Commun. 167, 103–128 (2005).

doi:10.1016/j.cpc.2004.12.014

63. G. J. Martyna, M. L. Klein, M. Tuckerman, Nosé-Hoover chains: The canonical ensemble

via continuous dynamics. J. Chem. Phys. 97, 2635–2643 (1992). doi:10.1063/1.463940

64. J. VandeVondele, J. Hutter, Gaussian basis sets for accurate calculations on molecular

systems in gas and condensed phases. J. Chem. Phys. 127, 114105 (2007).

doi:10.1063/1.2770708 Medline

65. S. Goedecker, M. Teter, J. Hutter, Separable dual-space Gaussian pseudopotentials. Phys.

Rev. B Condens. Matter 54, 1703–1710 (1996). doi:10.1103/PhysRevB.54.1703 Medline

66. G. J. Martyna, D. J. Tobias, M. L. Klein, Constant pressure molecular dynamics algorithms.

J. Chem. Phys. 101, 4177–4189 (1994). doi:10.1063/1.467468

http://dx.doi.org/10.1103/PhysRevLett.100.136406http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=18517979&dopt=Abstracthttp://dx.doi.org/10.1088/0953-8984/21/39/395502http://dx.doi.org/10.1088/0953-8984/21/39/395502http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=21832390&dopt=Abstracthttp://dx.doi.org/10.1103/PhysRevLett.77.3865http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10062328&dopt=Abstracthttp://dx.doi.org/10.1002/jcc.20495http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=16955487&dopt=Abstracthttp://dx.doi.org/10.1002/wcms.1159http://dx.doi.org/10.1016/j.cpc.2004.12.014http://dx.doi.org/10.1063/1.463940http://dx.doi.org/10.1063/1.2770708http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=17887826&dopt=Abstracthttp://dx.doi.org/10.1103/PhysRevB.54.1703http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9986014&dopt=Abstracthttp://dx.doi.org/10.1063/1.467468

abb8985-Lu-SM-FRONTabb8985-Lu-SM-BODYabb8985-Lu-SM-REFS