UV-visible dual-band photodetector based on an all-inorganic Mn-doped CsPbCl₃/GaN type-II heterojunction

The all-inorganic perovskite CsPbCl3 has attracted significant attention for its excellent carrier mobility and high optical absorption coefficient, demonstrating great potential for use as a high-performance photodetector. However, the severe toxicity of lead and its narrow-band response in the UV region pose a huge challenge to the application of the perovskite. In this study, we reduce the toxicity of CsPbCl3 by substituting Mn atoms for Pb atoms and introduce a wide-bandgap semiconductor p-GaN to improve the photoresponse of CsPbCl3 in the UV region. Mn-doped CsPbCl3/GaN heterojunction is prepared by transferring the synthesized Mn-doped CsPbCl3 precursor solution onto p-GaN substrates via the spin-coating method. The morphology and optical properties of the heterojunction are characterized in various ways, and the current-voltage characteristics and optical response properties of the Mn-doped CsPbCl3/GaN heterojunction photodetector are also measured. The rectification behavior and UV-visible dual-band response of the heterojunction are demonstrated, with the response in the UV region extending to 320 nm. Furthermore, the calculations, which are based on density functional theory, confirm that the optical absorption of the Mn-doped CsPbCl3/GaN heterojunction is significantly enhanced compared with that of the isolated material. Meanwhile, a type-II energy band arrangement is found at the heterojunction interface. The results of this study suggest that Mn-doped CsPbCl3/GaN heterojunctions are potential candidates for use as UV-visible dual-band photodetectors.