Effects of Ambient Gases on the Electrical Performance of Solution-Processed C8-BTBT Thin-Film Transistors

摘要

We performed a systematic study of the influence of environmental conditions on the electrical performance characteristics of solution-processed 2,7-dioctyl [1] benzothieno[3,2-b][1]-benzothiophene (C8-BTBT) thin-film transistors (TFTs). Four environmental exposure conditions were considered: high vacuum (HV), O~(2), N~(2), and air. The devices exposed to O~(2)and N~(2)for 2?h performed in a manner similar to that of the device kept in HV. However, the device exposed to air for 2?h exhibited significantly better electrical properties than its counterparts. The average and highest carrier mobility of the 70 air-exposed C8-BTBT TFTs were 4.82 and 8.07?cm_(2)V_(-1)s_(-1), respectively. This can be compared to 2.76?cm_(2)V_(-1)s_(-1)and 4.70?cm_(2)V_(-1)s_(-1), respectively, for the 70 devices kept in HV. Furthermore, device air stability was investigated. The electrical performance of C8-BTBT TFTs degrades after long periods of air exposure. Our work improves knowledge of charge transport behavior and mechanisms in C8-BTBT OTFTs. It also provides ideas that may help to improve device electrical performance further.