Organic Phototransistors Based on Self‐Assembled Microwires of n ‐Type Distyrylbenzene Derivative

Molecular design and crystallinity control are important issues for the development of high‐performance organic optoelectronic devices. Here, a highly photo‐responsive n ‐type organic small molecular semiconductor, (2Z,2′Z)‐3,3′‐(2,5‐dimethoxy‐1,4‐phenylene)bis(2‐(3,5‐bis(trifluoro‐methyl)phenyl)acrylonitrile) (DM‐R), was synthesized and the photoelectronic properties of self‐assembled DM‐R microwire organic phototransistors (MW‐OPTs) were studied. Significant enhancement in the electron mobility ( μ e ) of MW‐OPTs ( μ e : 0.16 cm 2  V −1  s −1 ) was observed as compared to thin‐film‐OPTs ( μ e : 2.7×10 −3  cm 2  V −1  s −1 ), most likely due to the single‐crystalline nature of the self‐assembled MWs. Moreover, the photoresponsivity of MW‐OPTs showed 23.53 (A W −1 ), which was 130 times higher than that of thin‐film OPTs (0.18 A W −1 ). Furthermore, the MW‐OPTs exhibited stable photoswitching properties and a faster charge accumulation/release rate than those of thin‐film OPTs. The results obtained herein demonstrate a facile solution‐based approach for the fabrication of high‐performance n ‐type organic MW‐OPTs and provide a systematic analysis platform of the photo‐generated charge carrier dynamics.