Atomic-level chemical reaction promoting external quantum efficiency of organic photomultiplication photodetector exceeding 108% for weak-light detection

Linlin Shi; Yizhi Zhu; Guohui Li; Ting Ji; Wenyan Wang; Ye Zhang; Yukun Wu; Yuying Hao; Kaiying Wang; Jun Yuan; Yingping Zou; Beng S Ong; Furong Zhu; Yanxia Cui

doi:10.1016/j.scib.2023.04.015

Atomic-level chemical reaction promoting external quantum efficiency of organic photomultiplication photodetector exceeding 10⁸% for weak-light detection

Sci Bull (Beijing). 2023 May 15;68(9):928-937. doi: 10.1016/j.scib.2023.04.015. Epub 2023 Apr 13.

Authors

Linlin Shi¹, Yizhi Zhu², Guohui Li³, Ting Ji¹, Wenyan Wang¹, Ye Zhang¹, Yukun Wu¹, Yuying Hao¹, Kaiying Wang⁴, Jun Yuan⁵, Yingping Zou⁵, Beng S Ong⁶, Furong Zhu⁷, Yanxia Cui⁸

Affiliations

¹ College of Optoelectronics, Key Laboratory of Interface Science and Engineering in Advanced Materials, Key Laboratory of Advanced Transducers and Intelligent Control System of Ministry of Education, Taiyuan University of Technology, Taiyuan 030024, China.
² College of Optoelectronics, Key Laboratory of Interface Science and Engineering in Advanced Materials, Key Laboratory of Advanced Transducers and Intelligent Control System of Ministry of Education, Taiyuan University of Technology, Taiyuan 030024, China; College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China.
³ College of Optoelectronics, Key Laboratory of Interface Science and Engineering in Advanced Materials, Key Laboratory of Advanced Transducers and Intelligent Control System of Ministry of Education, Taiyuan University of Technology, Taiyuan 030024, China. Electronic address: liguohui@tyut.edu.cn.
⁴ College of Optoelectronics, Key Laboratory of Interface Science and Engineering in Advanced Materials, Key Laboratory of Advanced Transducers and Intelligent Control System of Ministry of Education, Taiyuan University of Technology, Taiyuan 030024, China; Department of Microsystems, University of South-Eastern Norway, Horten 3184, Norway.
⁵ College of Chemistry and Chemical Engineering, Central South University, Changsha 410083, China.
⁶ Department of Physics, Research Centre of Excellence for Organic Electronics, Institute of Advanced Materials, Hong Kong Baptist University, Hong Kong, China. Electronic address: bong@hkbu.edu.hk.
⁷ Department of Physics, Research Centre of Excellence for Organic Electronics, Institute of Advanced Materials, Hong Kong Baptist University, Hong Kong, China. Electronic address: frzhu@hkbu.edu.hk.
⁸ College of Optoelectronics, Key Laboratory of Interface Science and Engineering in Advanced Materials, Key Laboratory of Advanced Transducers and Intelligent Control System of Ministry of Education, Taiyuan University of Technology, Taiyuan 030024, China; Shanxi-Zheda Institute of Advanced Materials and Chemical Engineering, Taiyuan 030032, China. Electronic address: yanxiacui@tyut.edu.cn.

PMID: 37085396
DOI: 10.1016/j.scib.2023.04.015

Abstract

Low-cost, solution-processed photomultiplication organic photodetectors (PM-OPDs) with external quantum efficiency (EQE) above unity have attracted enormous attention. However, their weak-light detection is unpleasant because the anode Ohmic contact causes exacerbation in dark current. Here, we introduce atomic-level chemical reaction in PM-OPDs which can simultaneously suppress dark current and increase EQE via depositing a 0.8 nm thick Al₂O₃ by the atomic layer deposition. Suppression in dark current mainly originates from the built-in anode Schottky junction as a result of work function decrease of hole-transporting layer of which the chemical groups can react chemically with the bottom surface of Al₂O₃ layer at the atomic-level. Such strategy of suppressing dark current is not adverse to charge injection under illumination; instead, responsivity enhancement is realized because charge injection can shift from cathode to anode, of which the neighborhood possesses increased photogenerated carriers. Consequently, weak-light detection limit of the forwardly-biased PM-OPD with Al₂O₃ treatment reaches a remarkable level of 2.5 nW cm^-2, while that of the reversely-biased control is 25 times inferior. Meanwhile, the PM-OPD yields a record high EQE and responsivity of 4.31 × 10⁸% and 1.85 × 10⁶ A W^-1, respectively, outperforming all other polymer-based PM-OPDs.

Keywords: Al(2)O(3); Atomic layer deposition; Interfacial; Organic photodetectors; Photomultiplication; Weak-light detection.