Pure Blue Emissive Lead Halide Perovskite Materials for Light-Emitting Diodes: Preparation, Progress, and Challenges

Metal halide perovskite nanocrystals (NCs) have emerged as promising candidates for next-generation materials in high-resolution and full-color displays owing to their exceptional color purity, high photoluminescence quantum yield (PLQY), and wide color gamut. Extensive research efforts have been dedicated to advancing the practical application of perovskite NCs in displays systems. To date, the external quantum efficiency (EQE) of red, green, and blue perovskite light-emitting diode (PeLED) devices has been boosted to over 25%, approaching the performance levels of cadmium-based LEDs. However, the performance of pure blue PeLEDs still falls short of the requirements for next-generation displays, posing a significant obstacle to the commercialization of perovskite NCs. This review begins by exploring strategies for achieving pure blue emissive perovskite NCs, including the use of mixed halides, quasi-2D perovskite structures, and quantum size effects. Subsequently, we provide a comprehensive overview of the current research landscape concerning CsPbBr₃ NCs with various dimensions, including quantum dots (0D), nanowires or nanorods (1D), and nanoplates (2D). These dimensional variations enable theeffective tuning of emission wavelength of NCs through quantum size effects, realizing their pure blue emission. Furthermore, we discuss approaches to enhance the photoelectric performance of pure-blue-emitting PeLEDs by optimizing key components such as the electron transport layer, hole transport layer, and perovskite emissive layer. Finally, we outline future directions and prospects for further improving the EQE of pure-blue-emitting PeLEDs.