Balancing Hole and Electron Conduction in Ambipolar Split-Gate Thin-Film Transistors

Hocheon Yoo,Fabrizio Torricelli,Jae-Joon Kim,Dong-Kyu Lee,Gerwin H Gelinck,Edsger C P Smits,Matteo Ghittorelli,Han-Koo Lee,Hyungju Ahn

doi:10.1038/s41598-017-04933-w

Abstract

Complementary organic electronics is a key enabling technology for the development of new applications including smart ubiquitous sensors, wearable electronics, and healthcare devices. High-performance, high-functionality and reliable complementary circuits require n- and p-type thin-film transistors with balanced characteristics. Recent advancements in ambipolar organic transistors in terms of semiconductor and device engineering demonstrate the great potential of this route but, unfortunately, the actual development of ambipolar organic complementary electronics is currently hampered by the uneven electron (n-type) and hole (p-type) conduction in ambipolar organic transistors. Here we show ambipolar organic thin-film transistors with balanced n-type and p-type operation. By manipulating air exposure and vacuum annealing conditions, we show that well-balanced electron and hole transport properties can be easily obtained. The method is used to control hole and electron conductions in split-gate transistors based on a solution-processed donor-acceptor semiconducting polymer. Complementary logic inverters with balanced charging and discharging characteristics are demonstrated. These findings may open up new opportunities for the rational design of complementary electronics based on ambipolar organic transistors.

Highlights

Ambipolar organic semiconductors, in which both holes and electrons can be injected and transported in a single semiconducting layer, significantly reduce the complexity of the fabrication processes
We show that hole and electron transport can be balanced by controlling the air exposure time and the temperature of the thermal treatment in poly-(diketopyrrolopyrrole-terthiophene) (PDPP3T) ambipolar semiconducting polymer
In order to further investigate the effect of air exposure on the hole transport in PDPP3T OTFTs, we extracted the width-normalized contact resistances (RP) as a function of the exposure time from the OTFTs electrical characteristics[54]

Summary

OPEN Balancing Hole and Electron

HocheonYoo[1], Matteo Ghittorelli 2, Dong-Kyu Lee[1], Edsger C. In conventional complementary OTFT technologies, the fabrication of p- and n-type transistors requires the separate deposition, patterning and optimization of two different semiconducting materials[11,12,13,14,15,16], one for each transistor type[17, 18] While this may seem to be a simple approach, in practice, the n-type and p-type organic semiconductors need to exhibit comparable electronic properties, requiring ad-hoc process conditions and optimizations[19, 20]. It has been reported that benzodifurandione-based oligo (p-phenylene vinylene) (BDOPV) exhibited ambipolar characteristics when fabricated under ambient condition while the same polymer showed unipolar n-type transport under nitrogen atmosphere[34] This indicates that the amount of air exposure can be a key design parameter to control electron and hole current in an ambipolar OTFT with a careful study of atmospheric effect. When the devices are connected in a complementary inverter configuration, larger gain and output swing were achieved compared to the values from inverters with unbalanced n/p characteristics

Results

Methods

Author Contributions

Additional Information