High mobility organic thin-film transistors based on p-p heterojunction buffer layer

Abstract

The p-p heterojunction of 5, 6, 11, 12-tetraphenylnaphthacene/vanadyl phthalocyanine, which has been used as the buffer layer, is demonstrated. The highest field-effect mobility is 5.1 cm2/Vs, which is one of the highest reported for polycrystalline rubrene thin film transistors. Current versus voltage characteristics of heterojunction diodes are utilized to investigate the charge injection mechanism, revealing the factors that bring about the improvement of carrier injection and the reduction of contact resistance. These results suggest that our approach is very promising to fabricate high performance organic thin-film transistors for practical applications in organic electronics.

High performance of rubrene thin film transistor by weak epitaxy growth method

“…Device l (cm 2 V À1 s À1 ) V th (V) I on/off m-7P/rubrene 5.1-8.8 À16 to À28 10 6 -10 8 m-7P/rubrene/VOPc 5.6-11.6 À10 to À26 10 5 -10 6 p-6P/rubrene a 2.4-3.0 À9 to À7 1 0 6 p-6P/rubrene/VOPc a 4.5-5.1 À7 to À5 1 0 6 a The data of device performance was reported by Xianrui Qian et al [29].…”

“…3b, which indicated that there existed a carrier injection barrier between rubrene thin film and Au electrodes just like the situation in the p-6P/rubrene system [29]. To reduce the carrier injection barrier and further enhance the device performance, VOPc was used as buffer layer between rubrene film and Au electrodes, which has been proved to be an efficient way before [29]. About 10 nm thick VOPc film was deposited on rubrene film at the same temperature to act as buffer layer.…”

Molecular Template Growth and Its Applications in Organic Electronics and Optoelectronics

“… a OFETs show ambipolar transport behavior with a hole mobility of 0.09 cm 2 /(V s) and electron mobility of 0.17 cm 2 /(V s) b OFETs using the p–p heterojunction of rubrene/VOPc as a buffer layer result in hole mobilities as high as 5.10 and 11.6 cm 2 /(V s), respectively. , c A hole mobility of 4.08 cm 2 /(V s) could be obtained if using an F 16 CuPc/CuPc heterojunction unit as a buffer layer to reduce contact resistance between the metal electrodes and VOPc. , …”

“…There are several MTG methods with different molecular template materials and growth behaviors, including multiphenyl- and multithiophene-based MTG, perylene-derivative MTG, acene MTG, and graphene/graphene oxide template growth. For example, much research progress into the weak epitaxy growth (WEG) method based on multiphenyl and multithiophene molecular templates has been achieved during the past several years, including extensions to new template layer materials and overlayer materials and new applications in organic electronics and optoelectronics. − Here, we summarize all research progress in this area to provide a better understanding of MTG and its applications.…”

Fully Integrated Microscale Quasi‐2D Crystalline Molecular Field‐Effect Transistors

“…According to the charge transfer effect investigated in a series of studies, it is reasonable to assume that energy band bending occurs at the F 16 CoPc/VOPc interface and electrons and holes accumulate in the F 16 CoPc and VOPc layers, respectively, improving the hole injection and transport from Au into the VOPc layer. Similarly, VOPc with a HOMO level of about 5.4 eV provides an efficient energy ladder for holes . Compared to a direct contact between Au and BTBT‐T 6 , for the contact Au/F 16 CoPc/VOPc/ BTBT‐T 6 it is easier for the hole carriers from the Au side to jump over the smaller energy barriers Au/VOPc and VOPc/BTBT‐T 6 , and efficiently enter the HOMO level of the BTBT‐T 6 layer.…”