White light-emitting diodes (LEDs) are becoming more prevalent for reducing the energy demand for lighting. But a key challenge for the LED lighting industry is to achieve the right photometric ranges and application-specific emission spectra while reducing costs. In the recent issue of Chemistry of Materials two research groups from Oxford and Cambridge (UK) investigated the synthesis of organic−inorganic Lead Halide perovskites in the form of colloidal crystals 5−10 nm in size for use as LED phosphors. They demonstrate that, as they tune the synthesis to reduce the size of the crystals the luminescence efficiency (PLQE) increases. Further manipulation of the perovskite crystals through selective mixing of the halide composition achieves broad emission covering the entire visible spectrum. By blending the perovskite crystals into an insulating and transparent polymer matrix, cast films shows enhanced stability in their spectral emission profile. It was demonstrated that multiple layers containing different perovskite crystals can also be stacked on top of each other to realize white light emission. Overall, they have demonstrated the emission of white light (and other desired color mixtures) when exciting perovskite crystal polymer composite films with a commercial blue LED, demonstrating their application as a complete solution as a phosphor replacement for lighting.
Read the full paper in Chemistry of Materials.