Ultra-bright and highly efficient inorganic based perovskite light-emitting diodes

Liuqi Zhang,Jingbi You,Edward H Sargent,Qi Jiang,Pengyang Wang,Hairen Tan,Mingyang Wei,Yang Yang,Xiaolei Yang,Brandon R Sutherland,Xingwang Zhang,Zhigang Yin

doi:10.1038/ncomms15640

Abstract

Inorganic perovskites such as CsPbX3 (X=Cl, Br, I) have attracted attention due to their excellent thermal stability and high photoluminescence quantum efficiency. However, the electroluminescence quantum efficiency of their light-emitting diodes was <1%. We posited that this low efficiency was a result of high leakage current caused by poor perovskite morphology, high non-radiative recombination at interfaces and perovskite grain boundaries, and also charge injection imbalance. Here, we incorporated a small amount of methylammonium organic cation into the CsPbBr3 lattice and by depositing a hydrophilic and insulating polyvinyl pyrrolidine polymer atop the ZnO electron-injection layer to overcome these issues. As a result, we obtained light-emitting diodes exhibiting a high brightness of 91,000 cd m−2 and a high external quantum efficiency of 10.4% using a mixed-cation perovskite Cs0.87MA0.13PbBr3 as the emitting layer. To the best of our knowledge, this is the brightest and most-efficient green perovskite light-emitting diodes reported to date.

Highlights

Inorganic perovskites such as CsPbX3 (X 1⁄4 Cl, Br, I) have attracted attention due to their excellent thermal stability and high photoluminescence quantum efficiency
CsPbBr3 perovskite thin films were fabricated by spin-coating a CsBr:PbBr2 precursor from dimethyl sulfoxide (DMSO) onto substrates, followed by annealing at 100 °C for 20 min to remove residual solvent and to induce perovskite crystallization
Real-time contact angle results showed that polyvinyl pyrrolidine (PVP)-modified ZnO films have increased hydrophilicity (Supplementary Fig. 1)

Summary

Introduction

Inorganic perovskites such as CsPbX3 (X 1⁄4 Cl, Br, I) have attracted attention due to their excellent thermal stability and high photoluminescence quantum efficiency. Solution-processed perovskite solar cells have demonstrated a high certified power conversion efficiency of 22.1%, which is comparable to photovoltaics made from traditional inorganic semiconductor materials such as Si, CIGS and CdTe (refs 1–8). They have been utilized as efficient low-threshold gain media in optically pumped lasers[9,10]. Perovskite materials exhibit high photoluminescence quantum yield (PLQY, 490% in solution for nanocrystals) and high colour purity with narrow emission linewidths o20 nm (refs 11–15) These features make them promising candidates as new materials for light-emitting diodes (LEDs). Combined with nanocrystal pinning and 2D perovskites, Rand et al achieved close to 10% EQE of organic–inorganic LEDs32

Methods

Results

Conclusion