High‐quality perovskite single crystals with large size are highly desirable for the fundamental research and high energy detection application. Here, a simple and convenient solution method, featuring continuous‐mass transport process (CMTP) by a steady self‐supply way, is shown to keep the growth of semiconductor single crystals continuously stable at a constant growth rate until an expected crystal size is achieved. A significantly reduced full width at half‐maximum (36 arcsec) of the (400) plane from the X‐ray rocking curve indicates a low angular dislocation of 6.8 × 10⁶ cm⁻² and hence a higher crystalline quality for the CH₃NH₃PbI₃(MAPbI₃) single crystals grown by CMTP as compared to the conventional inverse temperature crystallization (ITC) method. Furthermore, the CMTP‐based single crystals have lower trap density, reduced by nearly 200% to 4.5 × 10⁹ cm⁻³, higher mobility increased by 187% to 150.2 cm² V⁻¹ s⁻¹, and higher mobility–lifetime product increased by around 450% to 1.6 × 10⁻³ cm² V⁻¹, as compared with the ITC‐grown reference sample. The high performance of the CMTP‐based MAPbI₃ X‐ray detector is comparable to that of a traditional high‐quality CdZnTe device, indicating the CMTP method as being a cost‐efficient strategy for high‐quality electronic‐grade semiconductor single crystals.

A PbI₂ phase is found to be inevitably formed at the interface in dual-source evaporated perovskite films that will block carrier transport.

We report a prototypical device of CH₃NH₃PbCl₃ film ultraviolet photodetectors that were fabricated with a coplanar metal-semiconductor-metal Au interdigital electrode configuration. Pure phase CH₃NH₃PbCl₃ films with a good crystallinity were formed by a hybrid sequential deposition process featured with inter-diffusion of PbCl₂ and CH₃NH₃Cl upon annealing. The CH₃NH₃PbCl₃ film photodetector exhibits a high responsivity of 7.56 A /W at 360 nm, a ultraviolet/visible rejection ratio (R360 nm/R500 nm) was about two orders of magnitude and fast response speed with a rising time of 170 μs and a decay time of 220 μs. All the above results demonstrate CH₃NH₃PbCl₃ film photodetector as a competitive candidate in the application of visible blind UV detectors.

Flash evaporation is a vacuum-based evaporation method that is particularly suitable to prepare perovskite films for solar cell devices. Growth pressure has been found to be a critical parameter for perovskite film growth. The transport-determined growth mechanism is discussed in detail. The dense MAPbI₃ films can be achieved only under a low growth pressure of 5 × 10⁻³ Pa, while a rough surface covered by step-like grains and voids is found for MAPbI₃ films grown under a high Ar pressure of 10 Pa. In addition, we found that the presence of PbI₂ phase in the perovskite films could suppress the growth of the grain size; by using precursors with a high MAI/PbI₂ ratio, evaporated MAPbI₃ films with grain sizes larger than 500 nm can be achieved. The average power conversion efficiency of the perovskite solar cells increased from 1.82% to 10.01% with increasing grain size, indicating the universal importance of controlling the perovskite grain size for the performance improvement of solar cells based on both solution and evaporated perovskite films.