Enhanced Performance of Organic Field-Effect Transistors by a Molecular Dopant with High Electron Affinity

Abstract

Organic field-effect transistors (OFETs) are attractive for next-generation electronics, while doping plays an important role in their performance optimization. In this work, a soluble molecular dopant with high electron affinity, CN6-CP, is investigated to manipulate the performance of OFETs with a p-type organic semiconductor as the transport layer. The performance of the model 2,7-didodecyl[1]benzothieno[3,2-b][1]benzothiophene (C12-BTBT) bottom-gate top-contact (BGTC) OFETs is greatly optimized upon doping by CN6-CP, and the field-effect mobility is improved from 5.5 to 11.1 cm 2 V −1 s −1 , with a widely tunable threshold voltage from −40 to +5 V. Improvements in performance also appear in CN6-CP doped BGBC OFETs. As compared with commonly used molecular dopant F4-TCNQ, CN6-CP exhibits excellent doping effects and great potential for organic electronic applications.

Recent advances in doped organic field-effect transistors: mechanism, influencing factors, materials, and development directions

“…Yuanwei Zhu et al doped C12-BTBT with CN6-CP and F4-TCNQ in a BGTC device, respectively. 83 In this work, CN6-CP had higher solubility and showed a higher doping efficiency compared with F4-TCNQ as the dopant under the same conditions. Guanghao Lu reported reactive oxygen (oxygen plasma or ozone) treatments of 2,7didodecyl [1]benzothieno[3,2-b][1]benzothiophene (C12-BTBT), 84 and found that low-pressure oxygen plasma resulted in lowconcentration doping and maintained the hole mobility above 5 cm 2 V À1 s À1 .…”

Oxygen-Induced Barrier Lowering for High-Performance Organic Field-Effect Transistors

“…To evaluate the R c of the devices, the widely used transmission line method (TLM) − is employed, with channel lengths ( L ) ranging from 30 to 200 μm. TLM assumes that the total device resistance ( R on ) is the sum of source/drain R c and the channel resistance ( R ch ) which is proportional to the channel length.…”

Highly Conductive Ultrathin Layers of Conjugated Polymers for Metal-Free Coplanar Transistors with Single-Polymer Transport Layers

“…Vacuum doping, on the other hand, enables solvent-free doping and the deposition of a few nanometer-thick dopant molecules on the surface of the conjugated-polymer film, which not only lead to a significant enhancement of the conductivity of the conjugated polymer, − but also does not affect the crystallinity of the conjugated-polymer film excessively, ensuring the quality of the conductive film. In addition, vacuum doping is also advantageous in flexible electronic devices, which not only excludes the influence of solvent on the polymer, but also allows precise control of the doping region as well as the doping density in OFETs. − …”