Highly Enhanced Photoluminescence Quantum Yield of Phenethylammonium Halide-Passivated Inorganic Perovskite/Cellulose Nanocrystal Films

In recent years, perovskite quantum dots (PQDs) have become a promising candidate for developing next-generation displays due to their narrow emission width, tunable band gap, and near-unity photoluminescence quantum yield (PLQY). However, the major challenges of PQDs are their poor stability under oxygen-rich, high moisture, and continuous light irradiation conditions. Previously, we applied surface-functionalized cellulose nanocrystals (CNCs) to replace traditional ligands and successfully synthesized PQD/CNC films to improve the stability of PQDs. However, the PLQY of the PQDs/CNCs films is limited by the large crystals formed during the synthesis process. In this study, we incorporate phenethylammonium halide (PEAX, where X = Cl, Br, and I) during the synthesis process to form quasi-2D perovskite quantum well structures. The phenethylammonium halide provides a halide-rich environment and a more significant quantum confinement effect to PQDs in the CNC films. By combining the advantages of CNC and PEAX, stable light emission/conversion films with largely enhanced PLQY can be achieved. The PLQY of CsPbBr1.5Cl1.5, CsPbBr3, and CsPbBr0.5I2.5 films with PEAX passivation can be improved more than 8 (from 1.2 to 10%), 3 (from 22 to 69%), and 18 (from 3 to 55%) fold, respectively. Therefore, the synergistic approach of CNC and PEAX passivation for light emission/conversion films demonstrated herein holds the potential for developing full-color, stable, and high-performance displays in the future.