Polarization-passivation synergistic antisolvent strategy for high-brightness CsPbBr3 QLEDs exceeding 100,000 cd/m2

Abstract

The carrier injection limitation caused by the surface ligands of quantum dots (QDs) is a major challenge for achieving high-brightness emission in quantum dot light-emitting diodes (QLEDs). In this work, we enhanced the polarity of the antisolvent by incorporating inorganic bromides (ZnBr2) to improve ligand stripping capability, thereby achieving fewer insulating ligands to meet the demand for efficient carrier injection. Simultaneously, the inorganic bromide provided a Br-rich environment, suppressing the generation of Br vacancies under polar conditions, which frequently happened in traditional antisolvent strategies. Benefiting from this polarization-passivation synergistic strategy, ZnBr2-treated QDs exhibited a 17% reduction in ligand quantity and a 40% reduction in defect density, thus the photoluminescence quantum yield (PLQY) of ZnBr2-treated QDs increased from 47% to 86%. The fabricated QLEDs exhibited a 143% increase in current density and a maximum brightness reaching 104,126 cd/m2, which was 4.96 times that of samples treated with pure antisolvent. Correspondingly, the operational lifetime (T50@100 cd/m2) of the device extended from 20 h to 241 h. This simple inorganic bromide polarization-passivation synergistic strategy in QDs' purification engineering provides a new approach for realizing high-brightness QLEDs.