Small Molecule Approach to Passivate Undercoordinated Ions in Perovskite Light Emitting Diodes: Progress and Challenges

Abstract

Perovskite light-emitting diodes (PeLEDs) hold promise for the development of next-generation display and light technologies; however, various problems related to factors such as external quantum efficiency (EQE), long-term stability, and dependence on toxic species hinder their successful debut in display and lighting markets. Research on PeLEDs involving the small-molecule approach-the incorporation of small organic molecules into or onto active perovskite layers in PeLEDs for mitigating the aforementioned issues-has burgeoned in the last eight years. This review covers recent advances and challenges in the small-molecule approach by i) surveying the chemical structures used in the small-molecule approach, ii) summarizing the methods of molecular insertion into PeLED devices, iii) comprehensively discussing the effects of small-molecule-based interfacial engineering and passivation of undercoordinated metal and halide ions on the photophysical functions of devices and their mechanisms, iv) emphasizing the small-molecule-induced enhanced performance of devices in the context of long-term stability and EQE, and v) providing perspectives and discussing challenges for future research.