High Efficiency and Low Roll-Off Pure-Red Perovskite LED Enabled by Simultaneously Inhibiting Auger and Trap Recombination of Quantum Dots
Jie Guo, Mingyuan Xie, Hangren Li, Lin Zhang, Linxing Zhang, Xiaoyu Zhang, Weitao Zheng, Jianjun Tian
Abstract
CsPbI 3 perovskite quantum dots (QDs) could achieve pure-red emission by reducing their size, but the increased exciton binding energy ( E B ) and surface defects for the small-sized QDs (SQDs) cause severe Auger and trap recombinations, thus worsening their electroluminescence (EL) performance. Herein, we utilize the dangling bonds of the SQDs as a driving force to accelerate KI dissolution to solve its low solubility in nonpolar solvents, thereby allowing K + and I – to bond to the surface of SQDs. The E B of the SQDs was decreased from 305 to 51 meV because of the attraction of K + to electrons, meanwhile surface vacancies were passivated by K + and I – . The Auger and trap recombinations were simultaneously suppressed by this difunctional ligand. The SQD-based light-emitting diode showed a stable pure-red EL peak of 639 nm, an external quantum efficiency of 25.1% with low roll-off, and a brightness of 5934 cd m –2 .