[paper] Coplanar OTFT

Blurred Electrode for Low Contact Resistance in Coplanar Organic Transistors

Xiaolin Ye, Xiaoli Zhao, Shuya Wang, Zhan Wei, Guangshuang Lv, Yahan Yang, Yanhong Tong, Qingxin Tang, and Yichun Liu

American Chemical Society; Nano; Dec.18, 2020

DOI: 10.1021/acsnano.0c08122

*Center for Advanced Optoelectronic Functional Materials Research, and Key Lab of UV-Emitting Materials and Technology of Ministry of Education, Northeast Normal University, 5268 Renmin Street, Changchun 130024, China

Abstract: Inefficient charge injection and transport across the electrode/semiconductor contact edge severely limits the device performance of coplanar organic thin-film transistors (OTFTs). To date, various approaches have been implemented to address the adverse contact problems of coplanar OTFTs. However, these approaches mainly focused on reducing the injection resistance and failed to effectively lower the access resistance. Here, we demonstrate a facile strategy by utilizing the blurring effect during the deposition of metal electrodes, to significantly reduce the access resistance. We find that the transition region formed by the blurring behavior can continuously tune the molecular packing and thin-film growth of organic semiconductors across the contact edge, as well as provide continuously distributed gap states for carrier tunnelling. Based on this versatile strategy, the fabricated dinaphtho[2,3-b:2′,3′-f]thieno[3,2-b]thiophene (DNTT) coplanar OTFT shows a high field-effect mobility of 6.08 cm2 V–1 s–1 and a low contact resistance of 2.32 kΩ cm, comparable to the staggered OTFTs fabricated simultaneously. Our work addresses the crucial impediments for further reducing the contact resistance in coplanar OTFTs, which represents a significant step of contact injection engineering in organic devices.

Fig: Coplanar Organic Transistors (oTFTs)