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Effects of Confinement on Microstructure and Charge Transport in High Performance Semicrystalline Polymer Semiconductors
Author(s) -
Himmelberger Scott,
Dacuña Javier,
Rivnay Jonathan,
Jimison Leslie H.,
McCarthyWard Thomas,
Heeney Martin,
McCulloch Iain,
Toney Michael F.,
Salleo Alberto
Publication year - 2013
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201202408
Subject(s) - materials science , crystallinity , microstructure , annealing (glass) , semiconductor , thin film , crystallite , thin film transistor , organic semiconductor , charge carrier , electron mobility , composite material , nanotechnology , optoelectronics , metallurgy , layer (electronics)
The film thickness of one of the most crystalline and highest performing polymer semiconductors, poly(2,5‐bis(3‐tetradecylthiophen‐2‐yl)thieno[3,2‐b]thiophene) (PBTTT), is varied in order to determine the effects of interfaces and confinement on the microstructure and performance in organic field effect transistors (OFETs). Crystalline texture and overall film crystallinity are found to depend strongly on film thickness and thermal processing. The angular distribution of crystallites narrows upon both a decrease in film thickness and thermal annealing. These changes in the film microstructure are paired with thin‐film transistor characterization and shown to be directly correlated with variations in charge carrier mobility. Charge transport is shown to be governed by film crystallinity in films below 20 nm and by crystalline orientation for thicker films. An optimal thickness is found for PBTTT at which the mobility is maximized in unannealed films and where mobility reaches a plateau at its highest value for annealed films.