Mariacecilia Pasini15 Luglio 2009 Visita Panel

TOPIC: Synthesis, growth, preparation and processing of advancedmaterials, definition of fabrication procedure and mock-upTOPIC: Preparation and characterization of prototype LEDs and Bulk-Heterojunction Solar Cells based on advanced organic materials

OLED

PART1: Preparation and processing of polymeric materials for OLED (and Photovoltaics)PART2: OLEDs (and plastics solar cells) based on advanced organic materials

Mariacecilia Pasini

Mariacecilia Pasini15 Luglio 2009 Visita Panel

1

1

2

2

34

Steps of the electroluminescence process:

1. Charge (electrons and holes) injection2. Charge transport3. Charge recombination and exciton formation4. Exciton radiative relaxation EMISSION

GLASS or flexible substrate

OLED basic working principles

Mariacecilia Pasini

Mariacecilia Pasini15 Luglio 2009 Visita Panel

PART1:Conjugated block copolymer

BLOCK1i) Improved hole injection,

ii) Antioxidant action,iii) Morphological stabilityiv) Nano-encapsulation environment of the polymer chains

CHOICE OF THE BLOCKS

BLOCK2i)Improved electron transporting

ii)Good efficiencyiii)Nice CIE cordinates, PURE colour

350 400 450 500 550 600 650Wavelength (nm)

Excitation390nm390nm

535nm535nm Emission

OVERLAP

OK EnergyTransfer

Use all conjugated block copolymer approach toobtain materials with height efficiency and tunability

for lighting, multicolor displays and smart applications

To avoid demixing effect To finely control the structure of the compound with respect to random

copolymers It allows to exploit a resonant energy transfer (ET) mechanism to improve

polymer emission Soluble, then easy processable by spin-coating technique

Mariacecilia Pasini15 Luglio 2009 Visita Panel

How to link?Selected terminal groups by terminal quencher choice

GRAFTING ONTO: the MATERIAL

PFTPA1: n=7, Mw 7700, PD 2.2

PFTPA2: n=12, Mw 12900, PD 3.2

PFTPA3: n=27, Mw 28600, PD 3.2

DIFFERENT BLOCKS

PF8BT1: m=18, Mw 9700, PD 1.6

PF8BT2: m=5, Mw 2900, PD 2.1

StandardSuzuky

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RESULTS: DEVICES

Polyfluorene

to End‐capped copolymerEND2 Mn 29000 Mw/Mn 3.3

(PFTPA3)27 - (F8BT)

F8BT polymer

from Block‐copolymer

•Tunable material; In the aim of white emitting device we have a material emitting with two of the fundamental colors

THE CHEMIST: Playing with block lengths to address emission color

MODULATION OF COLOR

DICHROIC EMISSION

MODULATION OF ENERGY TRANSFER EFFICIENCY

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Selected block lengths to maximize the emission

From the Study of Blend

n=12, m=5 solid-state quantum yields up to 74% (comparable to highest efficient

blend), with demixing suppression

Simplest architecture

Max EQE1%

Max EQE1%

RESULTS: DEVICESPART2 :DEVICES OPTIMIZATION

0

1

2

3

4

5

6

7

η EXT [%

]

standard arch.

Ba/Al+ PVK

+ annealing

SUPER GREEN Max EQE5.5%

Max EQE5.5%

CIE 1931 Coordinates(0.36; 0.59)

Standard Green (0.31; 0.59)

Mariacecilia Pasini15 Luglio 2009 Visita Panel

MICRO OLED BY SOFT LITOGRAPHYMaster:

self-assembledPolystyrene

10μm

Micro-contactprinting

EL

PL

Replica Moulding in

PDMS

Thin Solid Films 492, 307 (2005)SEM

micro-OLEDSOrdered arrays of microsizedelectroluminescent spots

5µmEL PL

PDMS stamp inkedwith

electroluminescentpolymer

Completion ofOLED

Mariacecilia Pasini15 Luglio 2009 Visita Panel

S

S

MeO

MeO

S

S

MeO

MeO

S

S

MeO

MeO

S

S

MeO

MeO

S

S

MeO

MeO

S

S

MeO

MeO

S

S

MeO

MeO

S

S

MeO

MeO

S

S

MeO

MeO

S

S

MeO

MeO

S

S

MeO

MeO

S

S

MeO

MeO

S

S

MeO

MeO

S

S

MeO

MeO

S

S

MeO

MeO

S

S

MeO

MeO

S

S

MeO

MeO

S

S

MeO

S

S

MeO

Me O

S

S

MeO

Me O

S

S

M eO

MeO

S

S

MeO

M eO

S

S

M eO

MeO

S

S

MeO

MeO

MeO

400 700 1000Wavelength (nm)

EL

EC

TR

OL

UM

INE

SCE

NC

E

400 700 1000Wavelength (nm)

EL

EC

TR

OL

UM

INE

SCE

NC

E

Polarization⇔

EL Colour

Polarized Light-Emitting Diodes

Orientation by rubbing

5 µm

Picture using a polarizing filter

PolarizedEL Polarized

EL

Picture using a polarizing filter

Mariacecilia Pasini15 Luglio 2009 Visita Panel

DEVELOPMENTTOWARDS WHITE LIGHT

The sameapproach using a

red monomerExploitation of triplet emission by

using organometallic complexS

Eu

CF3

O

O

3N

N

OBTAINED AS SINGLE AND

CONTEPORANEOUSLY COLOURS We need RED!

PERSPECTIVES

M. Pasini et al. Chem.Phys.Chem. ASAP(2009);

U.Giovanella et al. Synth. Met. 158, 113(2008),

A.Bolognesi, et al. Macromol. 42, 1107-1113 (2009)

U.Giovanella et al. Adv. Mat.. submittedU.Giovanella, et al. J. Phys. Chem. C, 113, 2290 (2009)

Mariacecilia Pasini15 Luglio 2009 Visita Panel

ISMAC GROUP

A.Bolognesi, C.Botta, M.Catellani, S.Destri, F.Galeotti,

U.Giovanella, S.Luzzati, M.Pasini, W.Porzio, G.Scavia, P.Betti, C. Freund, J. Moreau V. Vhora, W.Mroz,F.Vignali, M.Parini, A.Arcari,L.Zulian.

€€-Fundings:MIUR-FIRB RBNE03S7XZ SynergyPRIN 2007PBWN44MIUR-FIRB LuciCariplo, Accordo Quadro Regione Lombardia

COLLABORATION

Dott. R.Zamboni(I), Prof. G.Farinola(I), Dott. G.Zotti(I), Dott. G:Barbarella(I), Prof. G:Gigli(I) Prof. S.Yunus(B), Prof L.De Cola(D), G.Hadziioannou(Fr), Prof. R:Tubino (I), Prof. J.Gierschner(S), Prof. G:Lanzani(I), Prof. G.Dellepiane(I), Centro RicercheFiat

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THANK YOU

Mariacecilia Pasini15 Luglio 2009 Visita Panel

PART1: Use all conjugated block copolymerapproach to obtain materials with heightefficiency and tunability for lighting, multicolordisplays and smart applications

AIM :produce high efficient OLED

WHY?-20% dell’energia elettrica -23 milioni di barili di petrolio all’anno negli USAReduction of CO2 emission

Mariacecilia Pasini15 Luglio 2009 Visita Panel

Max EQE5.5%

Max EQE5.5%

SUPER GREEN

CIE 1931 coordinates(0.36; 0.59)

standard green (0.31; 0.59)

0

1

2

3

4

5

6

7

η EXT [%

]

standard arch.

Ba/Al+ PVK

+ annealing

Selected block lengths to maximize the emission

From the Study of Blend

n=12, m=5 solid-state quantum yields up to 74% (comparable to highest efficient

blend), with demixing suppression

Simplest architecture

Max EQE1%

Max EQE1%

RESULTS: DEVICES

Mariacecilia Pasini15 Luglio 2009 Visita Panel

Part 1:Conjugated block copolymerTo avoid demixing effect,

To finely control the structure of the compound with respect to random copolymers.

It allows to exploit a resonant energy transfer (ET) mechanism to improve polymer emission

Soluble, then easy processable by spin-coating technique

BLOCK1i) improved hole injection,

ii) antioxidant action,iii) Morphological stabilityiv) nano-encapsulation

environment of the polymer chains

CHOICE OF THE blocks

BLOCK2i)Improved electron transportingii)Good efficiencyiii)Nice CIE cordinates, PURE colour

350 400 450 500 550 600 650Wavelength (nm)

excitation390nm390nm

535nm535nm Emission

OVERLAP

OK EnergyTransfer

Mariacecilia Pasini15 Luglio 2009 Visita Panel

OLED basic working principles

1

1

2

2

34

Steps of the electroluminescence process:

1. Charge (electrons and holes) injection2. Charge transport3. Charge recombination and exciton formation4. Exciton radiative relaxation EMISSION

GLASS or flexible substrate