Enhanced self-powered photoresponse in perovskite films with in situ induced p–n homojunction by Ar⁺ bombardment

In the past ten years, hybrid perovskite materials have attracted extensive research attention due to their outstanding physical properties. Further improvement in the photoresponsive performance is limited by the recombination of charge carriers in the perovskite films. Here, by controlling the stoichiometry of precursors, p-type perovskite films are obtained. The transformation of p-type to n-type in the surface layer of CH₃NH₃PbI₃ film is dramatically achieved by Ar⁺ bombardment. An n/p-type perovskite homojunction is successfully in situ induced, whose built-in electric field could promote the oriented transport of photo-induced carriers. This perovskite homojunction exhibits an increased I_light/I_dark ratio by almost one order of magnitude at room temperature under 532 nm light irradiation. The Ar⁺ bombardment method has generic appeal, and its key attributes-in situ induction of p–n homojunction-improve the unicity of preparation for growing perovskite homojunction and make this method potentially suitable for future multifunctional perovskite-based photoelectric devices.