Choi Junhwan, Kim Min Ju, Kim Joo-Young, Lee Eun Kyung, Lee Changhyeon, Park Youngkeun, Kang Juyeon, Park Jeong-Il, Cho Byung Jin, Im Sung Gap
Department of Chemical Engineering, Dankook University, 152 Jukjeon-ro, Yong-in, Gyeonggi-do, 16890, Republic of Korea.
Department of Electronics and Electrical Engineering, Dankook University, 152 Jukjeon-ro, Yong-in, Gyeonggi-do, 16890, Republic of Korea.
Small Methods. 2023 Nov;7(11):e2300628. doi: 10.1002/smtd.202300628. Epub 2023 Aug 1.
The interface between dielectric and organic semiconductor is critically important in determining organic thin-film transistor (OTFT) performance. Surface polarity of the dielectric layer can hinder charge transport characteristics, which has restricted utilization of polymeric dielectric materials containing polar functional groups. Herein, the electrical characteristics of OTFTs are analyzed depending on the alkyl chain length of organic semiconductors and surface polarity of polymer dielectrics. High-performance dibenzothiopheno[6,5-b:6',5'-f]thieno[3,2-b]thiophene (DBTTT) and newly synthesized its alkylated derivatives (C6-DBTTT and C10-DBTTT) are utilized as organic semiconductors. As dielectric layers, non-polar poly(1,3,5-trimethyl-1,3,5-trivinylcyclitrisiloxane) (pV3D3) and poly(2-cyanoethyl acrylate-co-diethylene glycol divinyl ether) [p(CEA-co-DEGDVE)] with polar cyanide functionality are utilized. The fabricated OTFTs with pV3D3 commonly exhibit the excellent charge transport characteristics. In addition, the OTFT performance is improved with lengthening the alkyl chain in organic semiconductors, which can be attributed to the molecular orientation of semiconductors. On the other hand, non-alkylated DBTTT OTFTs with polar p(CEA-co-DEGDVE) show relatively poor electrical characteristics, while their performance is drastically enhanced with the alkylated DBTTTs. The ultraviolet photoelectron spectroscopy (UPS) reveals that surface polarity of the dielectric layer can be abated with alkyl chain in organic semiconductors. It is believed that this study can provide a useful insight to optimize dielectric/semiconductor interface to achieve high-performance OTFTs.
介电层与有机半导体之间的界面对于确定有机薄膜晶体管（OTFT）的性能至关重要。介电层的表面极性会阻碍电荷传输特性，这限制了含有极性官能团的聚合物介电材料的应用。在此，根据有机半导体的烷基链长度和聚合物介电材料的表面极性分析了OTFT的电学特性。高性能的二苯并噻吩并[6,5-b:6',5'-f]噻吩并[3,2-b]噻吩（DBTTT）及其新合成的烷基化衍生物（C6-DBTTT和C10-DBTTT）被用作有机半导体。作为介电层，使用了具有极性氰基官能团的非极性聚（1,3,5-三甲基-1,3,5-三乙烯基环三硅氧烷）（pV3D3）和聚（丙烯酸2-氰基乙酯-共-二甘醇二乙烯基醚）[p(CEA-co-DEGDVE)]。采用pV3D3制备的OTFT通常表现出优异的电荷传输特性。此外，随着有机半导体中烷基链的延长，OTFT的性能得到改善，这可归因于半导体的分子取向。另一方面，具有极性p(CEA-co-DEGDVE)的未烷基化DBTTT OTFT表现出相对较差的电学特性，而其性能随着烷基化DBTTT的使用而大幅提高。紫外光电子能谱（UPS）表明，有机半导体中的烷基链可以减弱介电层表面的极性。相信这项研究可为优化介电/半导体界面以实现高性能OTFT提供有益的见解。
