Single Mode Lasing from CsPbBr₃ Microcrystals Fabricated by Solid State Space‐Confined Growth

Abstract All‐inorganic metal halide perovskites, such as CsPbX₃ (X = Br, Cl, or I), have attracted significant interest for a new generation of integrated, high‐performance optoelectronic devices. To realize the full potential of layer‐by‐layer devices, perovskite crystal thin films are preferred over crystal ingots, considering carrier loss during carrier transport. The space‐confined method is a facile way of fabricating perovskite crystal films in a geometrically confined space to break the isotropic growth. Many researchers have reported effective preparation of large‐area perovskite films using this method. However, most space‐confined methods require growth in a liquid phase (solution), which can cause uncontrollable nucleation, surface traps, and unsatisfactory device performance. In this work, a pure solid‐state space‐confined strategy to grow CsPbBr₃ films for the first time without relying on solution conditions is developed. The regular shapes of CsPbBr₃ films prepared by this solid‐state space‐confined strategy can function as effective multimode and single‐mode Fabry–Perot (F–P) microlasers under optical pumping. This work overcomes the challenge that the conventional space‐confined method can only be adapted to the liquid phase. It also opens a new approach for making high‐quality microlasers, which are significant for photonic integrated circuits and optoelectronic devices.