High Electron Mobility and Ambipolar Charge Transport in Binary Blends of Donor and Acceptor Conjugated Polymers |
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Authors: | A Babel Y Zhu K‐F Cheng W‐C Chen S?A Jenekhe |
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Affiliation: | 1. Department of Chemical Engineering and Department of Chemistry, University of Washington, Seattle, Washington 98195‐1750 (USA);2. Institute of Polymer Science and Engineering, Department of Chemical Engineering, National Taiwan University, Taipei, 106 (Taiwan) |
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Abstract: | 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 cm2 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 cm2 V–1 s–1 and a hole mobility of 1.0 × 10–4 cm2 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. |
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Keywords: | Conjugated polymers Electron transport Semiconductors polymer |
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