Enhancing quantum yield of CsPb(BrxCl1-x)3 nanocrystals through lanthanum doping for efficient blue light-emitting diodes

Abstract

Abstract All-inorganic perovskite quantum dots (PQDs) have attracted great attention in optoelectronic applications. However, compared with green and red PQDs, the poor photoluminescence quantum yield (PLQY) and terrible external quantum efficiencies (EQE) of blue-emission PQDs light-emitting diodes (QLEDs) have limited their further development in display field. Here, a general strategy for enhancing PLQY and EQE through lanthanum ions doping is proposed. Density functional theory (DFT) calculations confirmed that the partial substitution of La3+ for Pb2+ leads to a reduced defect states and an increased radiative recombination, meanwhile, a higher carrier temperature and exciton binding energy are also obtained. In consequence, a maximum PLQY of 84.3% is obtained for La3+-doped CsPb(BrxCl1-x)3 PQDs with emissions ranging from 448 to 500 nm. In terms of devices, phase separation and ion migration are effectively alleviated with La3+ profiting from the constricted lattice and stronger interaction between La and Cl. Resultantly, QLEDs with La3+-doped PQDs show the maximum EQE of 2.17% (480 nm) and 3.25% (489 nm), which is higher than state-of-the-art records at this wavelength.