Perovskite Light-emitting Diodes Based on Spontaneously Formed Submicrometre-scale Structures

Nature  ·  2018  ·  Impact 8

Yu Cao; Nana Wang; He Tian; Jingshu Guo; Yingqiang Wei; Hong Chen; Yanfeng Miao; Wei Zou; Kang Pan; Yarong He; Hui Cao; You Ke; Mengmeng Xu; Ying Wang; Ming Yang; Kai Du; Zewu Fu; Decheng Kong; Daoxin Dai; Yizheng Jin; Gongqiang Li; Hai Li; Qiming Peng; Jianpu Wang; Wei Huang;

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ABSTRACT

Light-emitting diodes (LEDs), which convert electricity to light, are widely used in modern society-for example, in lighting, flat-panel displays, medical devices and many other situations. Generally, the efficiency of LEDs is limited by nonradiative recombination (whereby charge carriers recombine without releasing photons) and light trapping . In planar LEDs, such as organic LEDs, around 70 to 80 per cent of the light generated from the emitters is trapped in the device , leaving considerable opportunity for improvements in efficiency. Many methods, including the use of diffraction gratings, low-index grids and buckling patterns, have been used to extract the light trapped in LEDs . However, these methods usually involve complicated fabrication processes and can distort the light-output spectrum and directionality . Here we demonstrate efficient and high-brightness electroluminescence from solution-processed perovskites that spontaneously form submicrometre-scale structures, which can efficiently extract light from the device and retain wavelength- and viewing-angle-independent electroluminescence. These perovskites are formed simply by introducing amino-acid additives into the perovskite precursor solutions. Moreover, the additives can effectively passivate perovskite surface defects and reduce nonradiative recombination. Perovskite LEDs with a peak external quantum efficiency of 20.7 per cent (at a current density of 18 milliamperes per square centimetre) and an energy-conversion efficiency of 12 per cent (at a high current density of 100 milliamperes per square centimetre) can be achieved-values that approach those of the best-performing organic LEDs.

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