Light-emitting field-effect transistors with EQE over 20% enabled by a dielectric-quantum dots-dielectric sandwich structure

Lingmei Kong; Jialong Wu; Yunguo Li; Fan Cao; Feijiu Wang; Qianqian Wu; Piaoyang Shen; Chengxi Zhang; Yun Luo; Lin Wang; Lyudmila Turyanska; Xingwei Ding; Jianhua Zhang; Yongbiao Zhao; Xuyong Yang

doi:10.1016/j.scib.2021.12.013

Light-emitting field-effect transistors with EQE over 20% enabled by a dielectric-quantum dots-dielectric sandwich structure

Sci Bull (Beijing). 2022 Mar 15;67(5):529-536. doi: 10.1016/j.scib.2021.12.013. Epub 2021 Dec 13.

Authors

Lingmei Kong¹, Jialong Wu¹, Yunguo Li², Fan Cao¹, Feijiu Wang³, Qianqian Wu¹, Piaoyang Shen¹, Chengxi Zhang¹, Yun Luo¹, Lin Wang¹, Lyudmila Turyanska⁴, Xingwei Ding⁵, Jianhua Zhang¹, Yongbiao Zhao⁶, Xuyong Yang⁷

Affiliations

¹ Key Laboratory of Advanced Display and System Applications of Ministry of Education, Shanghai University, Shanghai 200072, China.
² CAS Key Laboratory of Crust-Mantle Materials and Environments, School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, China.
³ Henan Key Laboratory of Photovoltaic Materials, Henan University, Kaifeng 475004, China. Electronic address: feijiu.wang@vip.henu.edu.cn.
⁴ Faculty of Engineering, University of Nottingham, Nottingham NG72RD, UK.
⁵ Key Laboratory of Advanced Display and System Applications of Ministry of Education, Shanghai University, Shanghai 200072, China. Electronic address: xwding@shu.edu.cn.
⁶ Center for Optoelectronic Engineering Research, Department of Physics, School of Physics and Astronomy, Yunnan University, Kunming 650091, China.
⁷ Key Laboratory of Advanced Display and System Applications of Ministry of Education, Shanghai University, Shanghai 200072, China. Electronic address: yangxy@shu.edu.cn.

PMID: 36546174
DOI: 10.1016/j.scib.2021.12.013

Abstract

Emerging quantum dots (QDs) based light-emitting field-effect transistors (QLEFETs) could generate light emission with high color purity and provide facile route to tune optoelectronic properties at a low fabrication cost. Considerable efforts have been devoted to designing device structure and to understanding the underlying physics, yet the overall performance of QLEFETs remains low due to the charge/exciton loss at the interface and the large band offset of a QD layer with respect to the adjacent carrier transport layers. Here, we report highly efficient QLEFETs with an external quantum efficiency (EQE) of over 20% by employing a dielectric-QDs-dielectric (DQD) sandwich structure. Such DQD structure is used to control the carrier behavior by modulating energy band alignment, thus shifting the exciton recombination zone into the emissive layer. Also, enhanced radiative recombination is achieved by preventing the exciton loss due to presence of surface traps and the luminescence quenching induced by interfacial charge transfer. The DQD sandwiched design presents a new concept to improve the electroluminescence performance of QLEFETs, which can be transferred to other material systems and hence can facilitate exploitation of QDs in a new type of optoelectronic devices.

Keywords: Electroluminescence; External quantum efficiency; Light-emitting field-effect transistors; Quantum dots.