Plasmonic Photonic Crystals Induced Two‐Order Fluorescence Enhancement of Blue Perovskite Nanocrystals and Its Application for High‐Performance Flexible Ultraviolet Photodetectors

Abstract Blue perovskite nanocrystal (NC) can be an ideal kind of material for UV photodetectors owing to its excellent band gap, however, limited by its photoacoustic process. Here, the luminescent enhancement of CsPbCl 3 NCs is first explored by coupling with Ag plasmon and photonic crystals. Consistently with the theoretical simulation, when the plasmon peak of Ag film and photonic stop band of polymethyl methacrylate opal photonic crystals (OPCs) match well with the emission peak of blue CsPbCl 3 NCs, the fluorescence enhancements of about 50‐fold and 20‐fold are obtained, owing to the collective effect of the excitation and emission field enhancement. Then, through the combination of surface plasmon and photonic crystal effects, the luminescent intensity of CsPbCl 3 NCs in CsPbCl 3 /Ag/OPCs hybrids is boosted more than 150‐fold with the estimated emission efficiency of 51.5%. Furthermore, the high performance flexible UV photodetector is constructed employing CsPbCl 3 /Ag/OPCs hybrids, demonstrating extremely low dark current of 10 –11 A, high detectivity of 9 × 10 14 Jones, short response time of 28 ms/31 ms, and narrow response line width of 30 nm, which is much better than the commercial silicon photodetectors. This work provides a helpful approach to improve the luminescence/performance of perovskite NCs and UV photodetectors.