Performance Improvement with an Ultrathin p-Type Interfacial Layer in n-Type Vertical Organic Field-Effect Transistors Based on Reduced Graphene Oxide Electrode

Kun Qiao; Shun Arakaki; Mitsuharu Suzuki; Ken-Ichi Nakayama

doi:10.1021/acsomega.2c02085

Performance Improvement with an Ultrathin p-Type Interfacial Layer in n-Type Vertical Organic Field-Effect Transistors Based on Reduced Graphene Oxide Electrode

ACS Omega. 2022 Jul 6;7(28):24468-24474. doi: 10.1021/acsomega.2c02085. eCollection 2022 Jul 19.

Authors

Kun Qiao¹, Shun Arakaki², Mitsuharu Suzuki¹, Ken-Ichi Nakayama¹

Affiliations

¹ Division of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan.
² Division of Applied Chemistry, School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan.

Abstract

Vertical organic field-effect transistors (VOFETs) with a large current on/off ratio and easy fabrication process are highly desirable for future organic electronics. In this paper, we proposed an ultrathin p-type copper (II) phthalocyanine (CuPc) interfacial layer in reduced graphene oxide (rGO)-based VOFETs. The CuPc interfacial layer was sandwiched between the rGO electrode and the N,N'-dioctyl-3,4,9,10-perylenedicarboximide (PTCDI-C₈) organic layer. The introduced CuPc interfacial layer not only decreased the off-current density of the device but also slightly enhanced the on-current density. The threshold voltage of the device was also effectively improved and stabilized at around 0 V. The obtained device exhibited a current on/off ratio exceeding 10⁶, which is the largest value reported for rGO-based VOFETs. The vertical electron mobility of the PTCDI-C₈ layer estimated by the space-charge-limited current technique was 1.14 × 10^-3 cm²/(V s). However, it was not the main limiting factor for the current density in this device. We totally fabricated 48 devices, and more than 75% could work. Besides, the device was stable with little performance degradation after 1 month. The use of low-cost, solution-processable rGO as work-function-tunable electrode and the application of an ultrathin CuPc interfacial layer in VOFETs may open up opportunities for future organic electronics.