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

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 La 3+ for Pb 2+ 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 La 3+ -doped CsPb(Br x Cl 1-x ) 3 PQDs with emissions ranging from 448 to 500 nm. In terms of devices, phase separation and ion migration are effectively alleviated with La 3+ profiting from the constricted lattice and stronger interaction between La and Cl. Resultantly, QLEDs with La 3+ -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.