Articleshttps://doi.org/10.1038/s41563-018-0081-x

Electron–phonon interaction in efficient perovskite blue emittersXiwen Gong   1, Oleksandr Voznyy   1, Ankit Jain1, Wenjia Liu1, Randy Sabatini   1, Zachary Piontkowski2, Grant Walters1, Golam Bappi1, Sergiy Nokhrin3, Oleksandr Bushuyev3, Mingjian Yuan1, Riccardo Comin1, David McCamant2, Shana O. Kelley   3,4 and Edward H. Sargent   1*

1Department of Electrical and Computer Engineering, University of Toronto, Toronto, ON, Canada. 2Department of Chemistry, University of Rochester, Rochester, NY, USA. 3Department of Chemistry, University of Toronto, Toronto, ON, Canada. 4Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, ON, Canada. *e-mail: ted.sargent@utoronto.ca

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Supplementary Materials for

Electron-Phonon Interaction in Efficient Perovskite

Blue Emitters

Xiwen Gong1, Oleksandr Voznyy1, Ankit Jain1, Wenjia Liu1, Randy Sabatini1, Zachary

Piontkowski2, Grant Walters1, Golam Bappi1, Sergiy Nokhrin3, Oleksandr Bushuyev3, Mingjian

Yuan1, Riccardo Comin1,

David McCamant2, Shana O. Kelley4,5,6 and Edward H. Sargent*1

1. Department of Electrical and Computer Engineering, University of Toronto, 10 King’s

College Road. Toronto, Ontario, M5S 3G4, Canada

2. Department of Chemistry, University of Rochester, 120 Trustee Rd., Rochester,

NY14627, USA

3. Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario

M5S 3H6

4. Institute of Biomaterials and Biomedical Engineering, University of Toronto, 164

College Street, Toronto, Ontario M5S 3G9, Canada.

5. Department of Pharmaceutical Sciences, Leslie Dan, Faculty of Pharmacy, University of

Toronto, 144 College Street, Toronto, Ontario M5S 3M2, Canada.

6. Department of Biochemistry, Faculty of Medicine, University of Toronto, Toronto,

Ontario M5S 1A8, Canada.

Corresponding E-mail: ted.sargent@utoronto.ca

Supplementary Figures and Tables:

Table S1| Solubility of perovskite precursor in DMF and DMSO; and their miscibility with

DEE.

Table S2| Summary of measured PLQE of single crystals (made from different organic cations) and standard organic dye. For C4, C12, PhC and PhC2 samples, 10 different batches of single crystals for each material were synthesized and exfoliated for the PLQY measurement.

DMF DMSO

Perovskite solubility (PhC2) (mmol/mL)

1.3 1.7

Miscibility with anti-solvent (volume ratio) 0 ≤

𝐷𝐸𝐸𝐷𝑀𝐹 < ∞ 0 ≤

𝐷𝐸𝐸𝐷𝑀𝑆𝑂 ≤ 1.5

Material C4 C12 Ph PhC PhC2 PhC3 DPA (Measured)

DPA (Reported)

PLQE of the champion sample (%)

17 12 <1 30 79 <1 85 88-95

Statistic PLQY (%)

15±3 10±2 <1 24±6 63±15 <1 NA NA

PL position Deep blue

Ultra-violet

White light

Deep blue

Deep blue

White light

Blue Blue Ref1 2

Peak position (nm)

417 392 415 411 411 415 427 430

Table S3| Summary of plain DFT results of PhC2 and C4.

Material PhC2 C4

Electron effective mass

(me)

3.194221233

0.323402471

Hole effective mass

(me)

0.280810658

0.257372987

Bohr radius (nm) 0.779049 1.35509

Table S4| Raman shifts and intensities of representative Raman modes.

PhC2_freqs (cm-1)

PhC2_ints (a.u.)

C4_freqs (cm-1)

C4_ints (a.u.)

63 6.3 68 60 81 6.3 97 83

116 4.5 131 102 133 7 296 23 154 4.8 402 4.8 304 1 427 4.2 420 0.25 467 12.6 467 0.76 889 2.6 491 0.12 932 7.8 573 0.068 941 24.3 761 0.3 1040 1.8 844 0.12 1075 1.9 887 0.4 1086 2.1 941 1.8 1123 2.3

1000 1.1 1312 1 1018 0.18 1448 1.2 1033 0.24 1491 7.4 1062 0.13 2872 5.6 1083 0.38 2909 9.1 1123 0.19 2932 7.8 1160 0.1 2967 6.6 1181 0.072 2985 2.9 1202 0.26 3040 3.3 1239 0.11

1307 0.08 1352 0.12 1382 0.064 1436 0.1 1473 0.51

1486 0.98 1584 0.21 1604 0.26 1648 0.1 2872 0.24 2907 0.55 2930 0.86 2974 0.75 2999 0.52 3040 0.81 3058 1.29

Table S5| Fitting results of temperature dependent FWHM

Material PhC2 C4 Γ3 (eV) 0.08326 0.02803 D (eV/cm) 7.4212×108 1.5205×109

Ratio of DMSO in DMSO/DMF

mixture

Time crystallization starts

Lateral size of the crystals (mm

2)

Relative PLQY (normalized to the highest value in the

experiment set)

0% 0.5 ~ 1 h < 1 0.4

5% ~ 1h 1~2 0.6

10% ~ 2h 2~4 0.6

20% ~ 5~10 h >10 0.9

30~60% > 18 h >10 1

Figure S 1| Engineering of ternary (DEE-DMF/DMSO) solvent system for higher quality crystal. The crystal size of PhC2 increases with higher DMSO component in the mixture of DMF/DMSO. However, if the DMSO ratio is higher than 60%, no crystal grows inside solution. We attribute that to the bad miscibility of DMSO with DEE.

Figure S 2| Shape and macroscopic morphology of crystal with different organic cation. C4

and PhC2 show layered structure, while Ph and PhC3 grow into needle-shape crystals.

Figure S 3| Crystal structure and optoelectronic properties of PhC3. In

comparison to PhC2, PhC3 shows non-2D structure, and no obvious excitonic

absorption peak was observed.

Figure S 4| Reduced reabsorption of exfoliated PhC2 crystal compared to bulk crystal. a, PL

peak shifts to blue region after exfoliating single crystals, indicating reabsorption is reduced with

thinner crystals. PLQE increases from 50% (bulk crystal) to the maximum of 80% (exfoliated

crystal). b, the PL of the unexfoliated large crystal fit with the tail of the PL of exfoliated sample,

as the result of the reabsorption of the bulk emission3.

Fig. S 5| power dependent PLQE measurement of PhC2 and C4.

Figure S 6| Electronic band-structure of C4, PhC2 and Ph. The band-structure of both C4 and

PhC2 is direct, while Ph shows indirect bandgap, which leads to low PLQE.

-1

0

1

2

3

4

5

Ene

rgy

(eV

)C4

0

1

2

3

4

PhC2

Ene

rgy

(eV

)

0

1

2

3

4

Ph

Ene

rgy

(eV

)

me=0.26mo

me=0.14mo

Figure S 7| Power dependent TA spectrum of C4 and PhC2. a, Power dependence of

C4 when pumped with 360 nm light, exciting across the bandgap. b, Power dependence of

PhC2 when pumped with 360 nm light, exciting across the band gap. c, Power dependence

of C4 when pumped with 460 nm light, exciting the traps. d, Power dependence of PhC2

when pumped with 460 nm light, exciting the traps.

Figure S 8| Defect density measurement through transient absorption. a, Comparison of

PhC2 and C4 spectra when pumped with 360 nm light. b, Comparison of PhC2 and C4 spectra

when pumped with 460 nm light. c, Comparison of PhC2 and C4 spectra when pumped with 460

nm light, normalized for crystal thickness and absorption cross section.

Figure S 9| Temperature dependent photoluminescence. a, PL intensity at the peak position. The slight

increase in PLQE may arise due to a gradual thermal activation of the bright excitonic state. This is common

for nanoscale emitters, where due to the exchange interaction, the lowest-energy exciton is dark (spin-

forbidden). At low temperature only this dark state is populated, whereas at higher temperature, the bright

(optically allowed) state is gradually activated. b and c, transient PL spectra of PHC2 and C4 and different

temperature.

Figure S 10| PL profile at different temperature of C4 and PhC2. The PL peak of both PhC2

and C4 exfoliated crystals shows small shift from 413 nm to 416 nm over the temperature range

from 10 K to 290 K. No phase transition was observed for the 2D perovskite single crystals.

Figure S 11| Raman Spectra. a, Raman spectra of C4 and C4 ligand. b, Raman spectra of PhC2

and phC2 ligand. Spectra have been scaled for concentration. Raman peaks of ligands show large

resonance enhancement when incorporated into perovskite structure.

Figure S 12| 13C CP-MAS spin-lattice relaxation rate (R1) fitting single crystals. a, C4 crystals,

b, PhC samples, and c PhC2 samples measured at 25°C. d, Summary of the relaxation rates of the

samples. Slower relaxation rate of the terminal aromatic carbons vs terminal methyl group (0.016

s-1 vs 0.5 s-1) indicate lower molecular mobility of organic cation terminus of PhC2. Comparing

the PhC single crystals with the PhC2 crystals, the relaxation rates of both the carbon in the phenyl

rings and the methyl carbon attached to the benzene ring are faster than their counterpart in PhC2,

indicating stronger vibration mode in PhC, which leads to lower PLQY.

Figure S 13| Comparison of the bandedge fluctuation between PhC and PhC2. Stronger

fluctuation is observed in PhC than PhC2, which is in line with the solid-state NMR results,

indicating more vibration in PhC. This results also explain the lower PLQY of PhC comes from

the less rigid structure and therefore stronger vibration.

Reference:

1. Brouwer, A. M. Standards for photoluminescence quantum yield measurements in

solution (IUPAC Technical Report). Pure Appl. Chem. 83, 2213–2228 (2011).

2. 9,10-Diphenylanthracene immobilized in mesostructured silica materials with a highly

efficient deep-blue fluorescent property. J. Lumin. 190, 154–160 (2017).

3. Wu, B. et al. Discerning the Surface and Bulk Recombination Kinetics of Organic-

Inorganic Halide Perovskite Single Crystals. Adv. Energy Mater. 6, 1600551 (2016).