Transferrable CsPbBr₃ Perovskite Single-Crystalline Films for Visible-Wavelength Photodetectors

In this study, we propose large-scale CsPbBr₃ (CPB) single-crystalline films (SCFs) grown by a one-step vapor-phase epitaxy (VPE) method for application in optoelectronic devices. After optimizing the transport speed of the precursor and cooling rate, we obtained continuous CPB films with a lateral size exceeding 2 cm², and the thickness could be controlled from several micrometers to hundreds of nanometers. Crystallography and optoelectronic characterization proved the excellent crystallinity and very low trap density (2.14 × 10¹¹) of the SCFs. Furthermore, we demonstrate a transfer-assembly strategy for fabricating perovskite SCF-based heterostructures for visible photodetectors. The high-quality SCF films in the active layer suppress the leakage current, leading to a low dark current of 5 × 10^-10 A at -0.6 V. Therefore, the self-biased photodetector based on the vertical CsPbBr₃ SCF-SnO₂ heterostructure showed a high responsivity of 1.9 A/W, a detectivity of 4.65 × 10¹² Jones, and a large on/off ratio of 4.63 × 10³ under a 1 mW/cm² 450 nm light illumination. Our study not only demonstrates the excellent performance of single-crystalline perovskite-based photodiodes but also provides a universal assembly method for the integration of monocrystalline perovskite films in optoelectronic devices.