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High Electron Mobility and Ambipolar Charge Transport in Binary Blends of Donor and Acceptor Conjugated Polymers
Author(s) -
Babel A.,
Zhu Y.,
Cheng K.F.,
Chen W.C.,
Jenekhe S. A.
Publication year - 2007
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.200600312
Subject(s) - ambipolar diffusion , materials science , electron mobility , transmission electron microscopy , phase (matter) , charge carrier , acceptor , polymer blend , analytical chemistry (journal) , polymer , electron , nanotechnology , optoelectronics , organic chemistry , condensed matter physics , chemistry , copolymer , composite material , physics , quantum mechanics
High electron mobility and ambipolar charge transport are observed in phase‐separated binary blends of n‐type poly(benzobisimidazobenzophenanthroline) (BBL) with p‐type polymer semiconductors, poly[(thiophene‐2,5‐diyl)‐ alt ‐(2,3‐diheptylquinoxaline‐5,8‐diyl)] (PTHQx) and poly(10‐hexylphenoxazine‐3,7‐diyl‐ alt ‐3‐hexyl‐2,5‐thiophene) (POT). Atomic force microscopy (AFM) and transmission electron microscopy (TEM) show phase‐separated domains of 50–300 nm in the binary blend thin films. The TEM images and electron diffraction of BBL/PTHQx blends show the growth of single‐crystalline phases of PTHQx within the BBL matrix. A relatively high electron mobility (1.0 × 10 –3 cm 2 V –1 s –1 ) that is constant over a wide blend‐composition range is observed in the PTHQx blend field‐effect transistors (FETs). Ambipolar charge transport is observed in both blend systems at a very high concentration of the p‐type semiconductor (≥90 wt % PTHQx or ≥80 wt % POT). Ambipolar charge transport is exemplified by an electron mobility of 1.4 × 10 –5 cm 2 V –1 s –1 and a hole mobility of 1.0 × 10 –4 cm 2 V –1 s –1 observed in the 98 wt % PTHQx blend FETs. These results show that ambipolar charge transport and the associated carrier mobilities in blends of conjugated polymer semiconductors have a complex dependence on the blend composition and the phase‐separated morphology.