Toward Stable Deep-Blue Luminescent Colloidal Lead Halide Perovskite Nanoplatelets: Systematic Photostability Investigation

Colloidal lead halide perovskite nanocrystals and nanoplatelets have emerged as promising semiconductor nanomaterials because of their spectral tunability, facile processability, and bright emission with high color purity. In particular, strong quantum and dielectric confinement make atomically thin colloidal lead bromide perovskite nanoplatelets a favorable candidate for next-generation deep-blue-emitting (λmax = 437 nm) materials. However, poor photostability poses a critical challenge; colloidal nanoplatelets suffer from photobleaching or transformation into thicker, less-confined nanostructures with red-shifted emission upon UV irradiation. In this study, we synthesize deep-blue-emitting organic–inorganic hybrid perovskite nanoplatelets (formula: L2[ABX3]BX4, L: butylammonium and octylammonium, A: methylammonium or formamidinium, B: lead, and X: bromide or iodide) with large lateral dimension (∼1 μm) by ligand-assisted reprecipitation and systematically investigate the factors that affect the photosta...