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Metal halide perovskite light-emitting diodes (PeLEDs) have developed rapidly and achieved tremendous progress in the last few years. However, the performance of blue PeLEDs still lags far behind their red and green counterparts. This review summarizes the optoelectronic properties and preparation methods of blue perovskite materials, proposes the strategies, challenges and perspectives for the further development of blue PeLEDs. [Display omitted] Metal halide perovskites, as a new generation of semiconductor materials, have been widely applied in various optoelectronic devices, especially in the field of perovskite light-emitting diodes (PeLEDs). The external quantum efficiencies (EQEs) of green, red, and near-infrared PeLEDs have exceeded 20% for the last few years, which are comparable to those of the state-of-the-art organic light-emitting diodes (OLEDs) and quantum-dot light-emitting diodes (QLEDs). However, the performances of blue PeLEDs lag far behind those of their counterparts, presumably due to the low quantum yields of blue perovskite films, the instability of the emission spectra, and the difficulties in charge injection for the devices under operation conditions. In this review, the structures and physical properties of blue emissive perovskite materials and the preparation methods of the corresponding perovskite films are firstly addressed. Then, the recent advances and strategies to improve the efficiency of blue PeLEDs are outlined, and the main challenges faced with the blue PeLEDs are also discussed. Finally, an outlook on blue LEDs based on perovskite materials is proposed. [ABSTRACT FROM AUTHOR]

Electroluminescent devices based on metal halide perovskites have attracted extensive attention owing to their high external quantum efficiency, excellent color purity, and inexpensive solution process. So far, extensive efforts have been made to improve the efficiency of the monochromatic perovskite light‐emitting diodes (LEDs). However, multicolor perovskite‐based LEDs are seldom studied. Here, an individual device capable of multicolor emission in response to the passage of external electric bias is demonstrated. With the rational design of the energy band alignment and control of the carrier transport property, color‐tunable electroluminescent devices based on inorganic halide perovskite and chalcogenide quantum‐dots are fabricated with a wide color tuning range, high color reversibility, and ultrafast color switching. The mechanism of chromaticity tuning is investigated and is explained by the shift of the exciton recombination zone with the driving voltage. The presented work will impact scientific communities by encouraging the manufacture of cost‐effective, high‐resolution, and full‐color displays and human‐centric lighting. [ABSTRACT FROM AUTHOR]

Metal halide perovskites have attracted considerable attention in the field of light‐emitting diodes due to their high color purity and solution processability. However, most perovskite light‐emitting diodes (PeLEDs) employ thermally deposited charge transport layers (CTLs) on top of perovskite layers. In order to realize low‐cost and scalable fabrication of PeLEDs, all‐solution process is highly desired, but still remaining great challenges. Here, an efficient all‐solution‐processed green PeLEDs is reported by incorporating 1,3,5‐tris(1‐phenyl‐1H‐benzimidazol‐2‐yl)benzene (TPBi) doped conjugated amino‐alkyl substituted polyfluorene poly[(9,9‐bis(3′‐(N,N‐dimethylamino)propyl)‐2,7‐fluorene)‐alt‐2,7‐(9,9‐dioctylfluorene)] (PFN) electron injection layer, achieving a maximum luminance of 9875 cd m−2, a high current efficiency of 10.41 cd A−1, and an external quantum efficiency of 3.19%. Since the solvents used for perovskite precursors and PFN are orthogonal, the protected and complete interface of perovskite film and CTL is effectively obtained by solution processes. The doping of TPBi into PFN not only enhances the capability of electron injection, but also significantly suppresses the emission quenching of perovskite films caused by the charge transfer between perovskite and PFN due to the reduced difference in their work functions. This work provides an efficient approach for the development of all‐solution‐processed PeLEDs. [ABSTRACT FROM AUTHOR]