Device performance improvements in all-inorganic perovskite light-emitting diodes: the role of binary ammonium cation terminals

Yao Lu; Jie Dong; Xiaomin Huo; Dong Wei; Bo Qiao; Suling Zhao; Dandan Song; Zheng Xu

doi:10.1039/d2cp00035k

Device performance improvements in all-inorganic perovskite light-emitting diodes: the role of binary ammonium cation terminals

Phys Chem Chem Phys. 2022 Mar 9;24(10):6208-6214. doi: 10.1039/d2cp00035k.

Authors

Yao Lu^{1

2}, Jie Dong^{1

2}, Xiaomin Huo^{1

2}, Dong Wei³, Bo Qiao^{1

2}, Suling Zhao^{1

2}, Dandan Song^{1

2}, Zheng Xu^{1

2}

Affiliations

¹ Key Laboratory of Luminescence and Optical Information, Beijing Jiaotong University, Ministry of Education, Beijing 100044, China. ddsong@bjtu.edu.cn.
² Institute of Optoelectronics Technology, Beijing Jiaotong University, Beijing 100044, China. zhengxu@bjtu.edu.cn.
³ College of Physics and Energy, Fujian Normal University, Fuzhou, 350117, China.

PMID: 35229093
DOI: 10.1039/d2cp00035k

Abstract

All-inorganic perovskites, like CsPbBr₃, have gained particular concern due to their excellent material stability. However, aside from the general defect issue in perovskite materials, all-inorganic perovskites also suffer from poor film quality, leading to low device efficiency, especially of perovskite light-emitting diodes (PeLEDs) employing a thin perovskite film as the emission layer. Herein, 1,4-phenyldimethylammonium dibromide (phDMADBr), which has ammonium cations (NH₃⁺) on both terminals, is introduced as the additive in the precursor solution. It is proved that phDMADBr can improve the film coverage; meanwhile, it also presents a more intense passivation effect on point defects than a similar additive with a single NH₃⁺ terminal. As demonstrated by density functional theory (DFT) calculations, phDMADBr tends to anchor onto the Br-dangling bond with both NH₃⁺ tails and enhances the adhesion to the perovskite grain surface. The exposed hydrophobic aryl also protects the perovskite from detrimental environmental factors. Correspondingly, the maximum luminance (L_max), current efficiency (CE), and device stability of the PeLEDs are enhanced. This work offers special guidance for screening passivation additives for inorganic perovskites.