Perovskite-based light-emitting diodes (PLEDs) have emerged as a promising alternative owning to the excellent optoelectronic properties including narrow emission linewidths, high photoluminescence quantum yield (PLQY), tunable emission wavelength, and high color purity. Over the past several years, significant progress has been obtained for green, red, and near-infrared PLEDs with a high external quantum efficiency (EQE) of over 20%. However, the development of blue PLEDs has been limited by several technical issues including poor film quality, inefficient device structure, higher trap density, and so on. To overcome these drawbacks with improved PLQY and EQE, we summarize and analyze the recent advances towards the development of three dimensional (3D), two dimensional (2D) and quasi-2D perovskites film employing composition and/or dimensional engineering. Moreover, the utilization of perovskite nanocrystals (PNCs) is also considered as a feasible strategy for the realization of high-performance blue PLEDs. We systematically evaluate the performance of sky-blue, pure-blue and deep blue PLEDs based on different perovskite materials. Finally, future prospective are proposed to promote the development of efficient blue PLEDs.

Flexible perovskite solar cells (FPSCs) have shown great potential in the field of wearable power supply and integration with architectures in the future due to their advantages of high flexibility, light weight, portability, and compatibility with irregular electronic products. As a promising photovoltaic technology compatible with roll-to-roll manufacturing process, FPSCs have made significant progress in the past several years through composition engineering, interface modification, optimization of fabrication process, and exploitation of new charge transport materials. As a result, the light-to-electricity power conversion efficiency of FPSCs has exceeded 20% recently. In this mini review, the latest developments of FPSCs are systematically summarized and discussed, including the flexible substrates and electrodes, as well as the fabrication of high-quality perovskite films. Finally, a prospect on the massive manufacturing of FPSCs as well as the challenge is also discussed.