Organic Electronic Devices

Transcription

1 Orgac Electroc Devces Week 1: Semcoductor Sythess ad Characterzato Lecture 1.1: A Itroducto to Orgac Electroc aterals Brya W. Boudours Chemcal Egeerg Purdue Uversty 1

2 Lecture Overvew ad Learg Objectves Cocepts to be Covered ths Lecture Segmet Chemcal Structures of Orgac Semcoductors Nomeclature of Commo Orgac Semcoductg aterals Desg Cosderatos for Small olecule ad acromolecular Orgac Semcoductg aterals olecular Weght Characterzato of Polymer Semcoductors Learg Objectves By the Cocluso of ths Presetato, You Should be Able to: 1. Draw the chemcal structure of a commo orgac semcoductor gve the ame ad/or recte the ame of a orgac semcoductor gve the chemcal structure of the materal. 2. Predct the relatve propertes of two orgac semcoductors gve the chemcal structure of the two materals. 3. Calculate the umber-average molecular weght, weght-average molecular weght, ad dspersty of a semcoductg polymer.

3 Uderstadg Devce Operato Requres Kowledge of aterals Orgac Lght-emttg Devce (OLED) Dsplays Th ad Lghtweght Flexble Trasparet Soy Samsug Orgac Photovoltac (OPV) Devces Polytro Large Area Producto Portable Applcatos Coformal Coverage Koarka Koarka Koarka

4 Geeral Characterstcs of Orgac Semcoductors I ths course, a orgac semcoductor has the followg propertes. 1. The materal s composed prmarly of carbo, hydroge, ad oxyge. Other atoms may be preset the materal, but the majorty (> 9%) of the mass these materals wll be hydrocarbo-based. 2. I geeral, the orgac semcoductors wll cota a great deal of alteratg sgle ad double bods (.e., they are π-cojugated materals). 3. Orgac semcoductors are va der Waals solds that have covalet bods betwee the atoms of the materals. Sgle Crystals Semcrystalle Nearly Amorphous Podzorov Research Group, podzorov/dex.php Toazz, I.; et al. Bophys. J. 21, 98, 284. Scale Bar = 1 µm va Djke, J. G.; Fleschauer,. D.; Brett,. J. J. ater. Chem. 211, 21, 113.

5 Commoly-used Small olecule Orgac Semcoductors Prmarly Hole Trasportg (p-type) Orgac Semcoductors Petacee etal (e.g., Cu or Z) TIPS-Petacee Rubree Phthalocyaes (Pc) Prmarly Electro Trasportg (-type) Orgac Semcoductors Buckmsterfulleree (C 6 ) PCB PTCBI Further Readg: shra, A.; Bäuerle, P. Agew. Chem. It. Ed. 212, 51, 22.

6 Commoly-used Polymerc Orgac Semcoductors Prmarly Hole Trasportg (p-type) Polymer Semcoductors EH-PPV P3AT PBDTTT-C PDTP-DFBT PEDOT:PSS Prmarly Electro Trasportg (-type) Polymer Semcoductors CN-EH-PPV BBL P(NDI2OD-T2) PT1 Further Readg: Boudours, B. W. Curr. Op. Chem. Eg. 213, 2, 294.

7 Desg Cosderatos for Polymer Electroc aterals Icreases Polymer Backboe Cojugato ad Th Flm Crystallty Teds to Improve the Charge Trasport Ablty Hgher olecular Weght Leads to Hgher Degrees of Crystallty Narrow olecular Weght Dstrbutos Lead to Hgher Degrees of Crystallty Fused Rgs Add to the Degree of Cojugato of the Polymer. Ths Leads to ore Charge Delocalzato ad, Geerally, To a Better Ablty to Trasport Charge Sde Chas Are Used to Icrease Solublty But Ca Have Secodary Effects wth Respect to Th Flm Structure Brached Sde Chas Help Icrease the Solublty of the Orgac Electroc aterals Greatly Sde Chas Ca Impact the Thermal, Structural, ad Optoelectroc Propertes of the Polymers by Chagg the Sold State Packg

8 Case Study: Poly(3-alkylthophees) (P3ATs) Powder WAXS Patters UV-Vs Absorpto Spectra μ h ~ 1-4 cm 2 V -1 s -1 μ h ~ 6 x 1-4 cm 2 V -1 s -1 μ h ~1-3 cm 2 V -1 s -1 Polymers ~1 μ chloroform solutos Spu-coat from chloroform for a Fal flm thckess of ~8 m Further Readg: Ho, V.; Boudours, B. W.; Segalma, R. A. acromolecules 21, 43, 7895.

9 Determato of the Number-average olecular Weght ( ) Polymers Cota a xture of acromolecular Szes 6-mer 1-mer 16-mer = 1 g mol -1 olar ass of a Repeat Ut: olecular Weght of a -mer wth umber of repeat uts: ole Fracto of a -mer: x = Number-average olecular Weght: = = x = = (1 6) + (2 1) + (1 16) = = ( 1 ) 1 1 g mol = 1, g mol

10 Determato of the Weght-average olecular Weght ( w ) Polymers Cota a xture of acromolecular Szes 6-mer 1-mer 16-mer = 1 g mol -1 olar ass of a Repeat Ut: olecular Weght of a -mer wth umber of repeat uts: Weght Fracto of a -mer: w Weght-average olecular Weght: = w = = w = = ( ) (1 6) + (2 1) + (1 16) w = = 1 g mol = 1,171 g mol (1 6) + (2 1) + (1 16)

11 Dspersty (Ð) ad the Impact o Orgac Electroc Devces Dspersty s a easure of the olecular Weght Dstrbuto Dspersty of a Polymer: Ð w, The: Ð Because: 1 w Dspersty Ca Be Thought of Terms of the Stadard Devato from the Average: 1 2 w σ = 1 = Ð 1 1 [ ] 2 Narrowg the Dspersty (.e., mzg the Stadard Devato ) of the Polymer Chas, Icreases the Ablty of the Polymer to Acheve a Hgher Degree of Crystallty. Ths, tur, Icreases the Charge Trasport Ablty of the Polymer the Sold State.

12 Summary ad Prevew of the Next Lecture Orgac electroc materals are molecular solds that cota covalet bods ad are composed maly of carbo, hydroge, ad oxyge. They cota a hgh degree of π-cojugato alog the ma cha of the molecules They ca form crystalle domas o the order of mllmeters, mcrometers, or aometers. The structure of the molecule dctates ts optoelectroc propertes. Orgac semcoductors The materals ca ether be small molecules or polymerc, ad they ca preferetally trasport holes (p-type) or electros (-type). The selecto of the fuctoal groups alog the polymer backboe ad the degree of cojugato affect the optoelectroc propertes of the materal. Furthermore, sde chas geerally are used to crease the solublty of the semcoductor soluto; however, they ca mpact the optoelectroc propertes as well. The umberaverage molecular weght, weght-average molecular weght, ad the dspersty of a polymer ca mpact the crystallty ad optoelectroc propertes of the materals. Next Tme: The Sythess of Oft-Used Polymer Semcoductors