Formamidinium–lead triiodide (FAPbI₃) shows strong potential for high-performance photodetectors owing to its narrow band gap and superior thermal stability. However, fabrication of pure-phase α-FAPbI₃ via a simple method remains challenging. Herein, a facile strategy based on antisolvent engineering is introduced to obtain pure-phase FAPbI₃ perovskite films by incorporating 3,5-difluorobenzylamine (DFBZ) into one-step antisolvent chlorobenzene. The findings reveal that the DFBZ molecule can effectively control the crystallization of perovskite and improve α phase stability of FAPbI₃ perovskite. The perovskite films incorporating DFBZ exhibit a more uniform and denser surface morphology as well as prolonged carrier lifetime. The resulting photodetectors demonstrate a broad spectral response from 300 to 850 nm, with a responsivity of up to 0.49 A·W⁻¹ at 770 nm. The DFBZ molecule can effectively passivate perovskite crystal defects and also improve the stability of perovskite films. The optimized devices retain approximately 90% of their initial performance after storage in air environment of 25 °C and a relative humidity of 30% for 400 h. The strategy provides an effective route to prepare stable pure-phase α-FAPbI₃ perovskite films and broadband photodetectors.

Perovskite single-crystal arrays have attracted intensive attention because of their great potentials for integrated optoelectronic devices. However, the traditional top-down lithography strategy requires complex processing and is detrimental to perovskite crystal structures, which is incompatible to directly pattern perovskite single crystals. Herein, we report a lithography-free method to realize the controllable growth of perovskite single-crystal arrays. Through introducing a printed hydrophilic-hydrophobic substrate into the crystallization system, the MAPbCl₃ single-crystal arrays with precise location and uniform size are effectively fabricated. This method can be applied to prepare diverse perovskite single-crystal arrays, including MAPbBr₃, CsPbCl₃, CsPbBr₃, Cs₃Cu₂I₅, Cs₃Bi₂I₉, and (BA)₂(MA)₃Pb₄I₁₁. The perovskite single crystals can be selectively grown on the electrodes to fabricate ultraviolet photodetectors. The strategy demonstrates a facile approach to fabricate large-scale perovskite single-crystal arrays and opens a pathway to produce diverse perovskite optoelectronic devices.