Inorganic perovskites with special semiconducting properties and structures have attracted great attention and are regarded as next generation candidates for optoelectronic devices. Herein, using a physical vapor deposition process with a controlled excess of PbBr , dual-phase all-inorganic perovskite composite CsPbBr -CsPb Br thin films are prepared as light-harvesting layers and incorporated in a photodetector (PD). The PD has a high responsivity and detectivity of 0.375 A W and 10 Jones, respectively, and a fast response time (from 10% to 90% of the maximum photocurrent) of ≈280 µs/640 µs. The device also shows an excellent stability in air for more than 65 d without encapsulation. Tetragonal CsPb Br provides satisfactory passivation to reduce the recombination of the charge carriers, and with its lower free energy, it enhances the stability of the inorganic perovskite devices. Remarkably, the same inorganic perovskite photodetector is also highly flexible and exhibits an exceptional bending performance (>1000 cycles). These results highlight the great potential of dual-phase inorganic perovskite films in the development of optoelectronic devices, especially for flexible device applications.

MXenes have been demonstrated as a potential candidate in the field of photovoltaics and energy storage owing to their high transmittance, metallic conductivity and tunable work function.

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Halogen vacancies are of great concern in blue‐emitting perovskite quantum‐dot light‐emitting diodes because they affect their efficiency and spectral shift. Here, an enriched‐bromine surface state is realized using a facile strategy that employs a PbBr2 stock solution for anion exchange based on Cd‐doped perovskite quantum dots. It is found that the doped Cd ions are expected to reduce the formation energy of halogen vacancies filled by the external bromine ions, and the excess free bromine ions in solution are enriched in the surface by anchoring with halogen vacancies as sites, accompanied with the shedding of surface long‐chain ligands during the anion exchange process, resulting in a Br‐rich and “neat” surface. Moreover, the surface state exhibits good passivation of the surface defects of the controlled perovskite QDs and simultaneously increases the exciton binding energy, leading to excellent optical properties and stability. Finally, the sky‐blue emitting perovskite quantum‐dot light‐emitting diodes (QLEDs) (490 nm) are conducted with a record external quantum efficiency of 14.6% and current efficiency of 19.9 cd A−1. Meanwhile, the electroluminescence spectra exhibit great stability with negligible shifts under a constant operating voltage from 3 to 7 V. This strategy paves the way for improving the efficiency and stability of perovskite QLEDs.