Stretchable Primary-Blue Color-Conversion Layer: <i>In Situ</i> Crystallization of Phase-Engineered Perovskite Nanocrystals in an Organic Matrix

Although the use of ultraviolet (UV) light-emitting diode backlight with red, green, and blue color-conversion layers (CCLs) in displays simplifies the manufacturing process and improves display uniformity, research on blue CCLs remains limited and has been mostly reported in the sky-blue region (> 470 nm), which is insufficient to satisfy the Rec. 2020 color standard. As halide perovskites offer a high extinction coefficient, color purity, and photoluminescence quantum yield (PLQY), they become highly competitive color-converting materials for CCLs. This work presents a simple method for the <i>in situ</i> fabrication of perovskite nanocrystal (NC) films for primary-blue CCL and additionally proposes a set of scientific guidance rules regarding significant factors that affect the nucleation and <i>in situ</i> crystallization kinetics of perovskite NCs. The fabricated films are highly stretchable, emit bright primary-blue light (∼460 nm), and have PL that is tolerant to UV irradiation. By introducing fluorinated arylammonium salts, the quantum and dielectric confinement effects are desirably adjusted, which induces efficient energy transfer processes for primary-blue emission. This strategy yields phase-engineered perovskite NCs embedded in an organic matrix, which enables spectrally stable and robust PL under high tensile strain (> 250%) and after prolonged UV irradiation (> 40 d). Consequently, this work demonstrates that the <i>in situ</i> fabricated stretchable blue CCLs achieve 100% agreement with Rec. 2020.