金属卤化物钙钛矿纳米晶高效发光二极管的制备与器件性能优化

金属卤化物钙钛矿作为一类新型的离子型直接带隙半导体材料在电致发光二极管(LED)中有着重要应用前景. 但实现其应用的前提在于金属卤化物钙钛矿材料需要保持高的发光效率和好的稳定性. 为了提高金属卤化物钙钛矿作为LED发光层的激子结合效率， 从而提升其发光效率, 设计和合成金属卤化物钙钛矿纳米晶材料是一个有效途径. 目前, 基于纳米晶材料设计的金属卤化物钙钛矿LED在绿光和红光(包括近红外光)范围已经展现了高的发光亮度和外量子效率(EQE), 其中最高EQE已经超过了20%, 但其稳定性仍无法满足器件应用的要求. 此外, 更值得关注且更重要的是, 蓝光钙钛矿LED的发光亮度和EQE目前仍然不高. 如何制备高效、 稳定的金属卤化物钙钛矿纳米晶LED, 特别是蓝光LED, 是一个具有重大应用前景且具有挑战性的课题. 本文重点介绍了金属卤化物钙钛矿纳米发光层的结构设计和合成方法及金属卤化物钙钛矿LED的研究进展, 分析了金属卤化物钙钛矿LED不稳定的原因, 并对金属卤化物钙钛矿LED研究面临的挑战和未来发展方向进行了总结与展望.

Synthesis and Device Optimization of Highly Efficient Metal Halide Perovskite Light-emitting Diodes

Metal halide perovskites have emerged as a new family of semiconducting materials in the applications of highly efficient light-emitting diodes（LEDs）. However， the efficient and stable metal halide perovskite LED could be achieved only if the low photoluminescent（PL） efficiency and instability issues of metal halide perovskite materials are addressed. In order to increase the exciton binding energy of the metal halide perovskite as an emitting layer in the LED， the fabrication of nano-sized perovskite is an effective way， which can increase the exciton binding energy by reducing the size or dimension， thus increasing photoluminescent efficiency. Though the perovskite-based LEDs in the green and red light spectral range have demonstrated high brightness and good efficiency， the highest external quantum efficiencies（EQEs） of which are even exceeding 20%， their stability still cannot satisfy the requirements of practical applications. More importantly， the performance of blue metal halide perovskite LED is still limited by the low light emission efficiency of present metal halide perovskites. Therefore， the fabrication of highly efficient and stable perovskite LEDs， especially the blue perovskite LED， is the most challenging issue for realizing the practical application of perovskite LEDs. In this review， we have summarized the strategies to synthesize the perovskite emitter layers and reviewed the research progress of metal halide perovskite LEDs. We also discussed the causes of instability of metal halide perovskite LED， and finally we present insight toward future research directions and an outlook to further improve EQEs and stabilities of perovskite LEDs aiming to practical applications.