Optimizing the Performance of Perovskite Nanocrystal LEDs Utilizing Cobalt Doping on a ZnO Electron Transport Layer

Chengyuan Tang; Xinyu Shen; Xiufeng Wu; Yuan Zhong; Junhua Hu; Min Lu; Zhennan Wu; Yu Zhang; William W Yu; Xue Bai

doi:10.1021/acs.jpclett.1c03060

Optimizing the Performance of Perovskite Nanocrystal LEDs Utilizing Cobalt Doping on a ZnO Electron Transport Layer

J Phys Chem Lett. 2021 Oct 21;12(41):10112-10119. doi: 10.1021/acs.jpclett.1c03060. Epub 2021 Oct 11.

Authors

Chengyuan Tang¹, Xinyu Shen¹, Xiufeng Wu¹, Yuan Zhong¹, Junhua Hu², Min Lu¹, Zhennan Wu¹, Yu Zhang¹, William W Yu³, Xue Bai¹

Affiliations

¹ State Key Laboratory of Integrated Optoelectronics and College of Electronic Science and Engineering, Jilin University, Changchun 130012, China.
² Key Laboratory of Materials Physics of Ministry of Education and Department of Physics and Engineering, Zhengzhou University, Zhengzhou 450052, China.
³ Department of Chemistry and Physics, Louisiana State University, Shreveport, Louisiana 71115, United States.

PMID: 34633816
DOI: 10.1021/acs.jpclett.1c03060

Abstract

Metal halide perovskite nanocrystal (PNC) light-emitting devices (LEDs) are promising in the future ultra-high-definition display applications due to their tunable bandgap and high color purity. Balanced carrier injection is indispensable for realizing highly efficient LEDs. Herein, cobalt (Co) was doped into ZnO to modulate the electron mobility of a pristine electron transport layer (ETL) and to inhibit exciton quenching at the ZnO/EML interface due to the passivation of oxygen vacancies and the reduction of electron concentration resulting from the trapping of electrons by the Co²⁺-induced deep impurity level. Also, the bandgap was widened due to the size confinement effect. All of those were beneficial to achieve a balanced charge injection during the operating process. Consequently, the maximum luminance increased from 867 cd m^-2 for ZnO LEDs to 1858 cd m^-2 for Co-doped ZnO LEDs, and there was a 70% increase of external quantum efficiency (EQE). By further inserting a polyethylenimine (PEI) layer in the Co-doped ZnO LEDs, the EQE reached 13.0%.