The Past, Present, and Future of Metal Halide Perovskite Light-Emitting Diodes.

Metal halide perovskites (MHPs) have emerged as new-generation highly efficient narrow-band luminescent materials with applications in various optoelectronic devices, including photovoltaics (PVs), light-emitting diodes (LEDs), lasers, and scintillators. Since the demonstration of efficient room-temperature electroluminescence from MHPs in 2014, remarkable progress has been achieved in the development and study of light-emitting MHP materials and devices. While the device efficiencies of MHP LEDs (PeLEDs) have significantly improved over a short period of time, their overall performance has not reached the levels of mature technologies yet, such as organic LEDs (OLEDs) and quantum dot LEDs (QDLEDs), to enable practical applications. Many issues and challenges, including low operational stability, lack of efficient blue PeLEDs, and toxicity of MHPs, remain to be addressed. Herein, some of the most exciting progress achieved in the development of efficient and stable PeLEDs during the last few years are introduced, the main issues and challenges in the field are discussed, and the prospects on addressing these issues and challenges are provided. With continuous effort, the potential of PeLEDs to become a commercially available LED technology for display and lighting applications in the future looks optimistic.