In Situ Polymer‐Imprinted Architecture of Textured Perovskite Single‐Crystal Sheets for Ultraweak‐Light Photodetection

Abstract A facile double flexible interfacial imprinting method is reported to obtain the cubic single‐crystal CH₃NH₃PbBr₃ sheets with in situ polymer patterns by capillary effect. The imprinted CH₃NH₃PbBr₃ sheets offer good crystallinity and light‐trapping structure. As a result, the textured single‐crystal photodetector exhibits the superior responsivity of 63.0 A W⁻¹, external quantum efficiency of 1.50 × 10⁴%, and detectivity D* of 8.12 × 10¹² Jones under 520 nm irradiations with a weak power density of 0.54 µW cm⁻² at 3 V, which are more than 4200% and 80000% higher than those of the photodetector based on single‐crystal bulk and polycrystalline film, respectively. The exciting ultraweak‐light photoelectric performance is achieved due to the good light trapping and high carrier collection. Especially, the photodetector also exhibits excellent self‐powered performance.