Stretchable\nPrimary-Blue Color-Conversion Layer: <i>In Situ</i> Crystallization\nof Phase-Engineered Perovskite Nanocrystals\nin an Organic Matrix

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