Although epitaxial growth is the fundamental method to realize lattice matched heterojunctions in electronics manufacturing, large-scale epitaxial single crystal layers based on solution-processing have rarely been reported. Here, cascade organic−inorganic hybrid perovskite single crystals with purity quotient over 99.9% consisting of chlorine, bromine, and iodine are fabricated by solution-processed epitaxial growth, in which the mismatch rate between adjacent layers is less than 1%. The area of solution-processed epitaxial growth is proved up to 4 cm 2 , and the speed reaches nearly 100 nm s −1 . The resulting high-quality interface effectively improves bonding between adjacent layers, and the average mobility is calculated to be over 200 cm 2 V −1 s −1 in samples with different structures. Based on a specific structure with n-type, p-type, and intrinsic layers, a 7.55 mm-thickness X-ray photodiode with sensitivity 1.58 μC mGy −1 cm −2 is fabricated. This work provides a different method for fabricating solution-processed based electronic devices and makes stable perovskite-based devices more accessible.

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Dual-mode photodetectors (PDs) have attracted increasing interest owing to their potential optoelectrical applications. However, the widespread use of PDs is still limited by the high cost of epitaxial semiconductors. In contrast, the solution processability and wide spectral tunability of perovskites have led to the development of various inexpensive and highperformance optoelectronic devices. In this study, we develop a high-performance electronically modulated dual-mode PD with near-infrared (NIR) narrowband and visible light broadband detection based on organic−inorganic hybrid methylammonium lead halide perovskite (MAPbX 3 ; MA = CH 3 NH 3 and X = Cl, Br, and I) single crystals with a pnp configuration. The operating mode of the dual-mode PD can be switched according to voltage bias polarity because the photon absorption region and carrier transport performance are tuned at different bias voltages. The dual-mode PD exhibits a NIR light responsivity of 0.244 A/W and a narrow full width at half-maximum of ∼12 nm at 820 nm at positive voltages and an average visible light responsivity of ∼0.13 A/W at negative voltages. The detectivities of both modes are high (∼10 12 Jones), and the linear dynamic range is wide (>100 dB). Our study provides a new method for fabricating multifunctional PDs and can expand their application in integrated imaging systems.

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The ion migrations in lead halide perovskite (LHP)‐based devices are complex processes due to the generation of charges and migration multipaths. The migrating ions are generated mainly from element defects and dislocation defects, and transport along paths of element vacancies and grain boundaries. In this regard, it is of interest to investigate the different influences of the two defect types and paths. Herein, the current–voltage hysteresis and X‐ray photoelectron spectra of almost‐dislocation‐free LHP single crystals (LHPSCs) with different halide components are investigated. The ions cannot migrate in iodine‐based LHPSCs. A decrease in halide vacancy content in a bromine–chlorine‐based perovskite single crystal can effectively limit the ion migration. This study provides useful insights to understand the different dominant factors determining the ion migration in LHPs.