Fabrication of [001]-Oriented FAPbI₃-Based Photodetector With Excellent Air Stability Via Green Anti-Solvent Additive Engineering

Formamidinium lead triiodide (FAPbI(3)) exhibits excellent thermal and chemical stability, making it a suitable alternative for methylammonium lead triiodide (MAPbI(3)) in high-performance photodetectors. However, FAPbI(3) faces the challenge of transforming from the metastable photoactive black phase alpha-FAPbI(3) to the photoinactive yellow phase delta-FAPbI(3) at room temperature. This phase transition is accelerated in humid atmospheric conditions. To realize high-performance FAPbI(3)-based photodetectors, it is crucial to form stable and highly crystalline phase-pure alpha-FAPbI(3) films. Herein, is fabricate highly stable and crystalline FAPbI(3) films and photodetectors through anti-solvent additive engineering (AAE) using a green anti-solvent (isopropanol, IPA) and an organic spacer (phenethylammonium iodide, PEAI). It is found that PEAI-AAE treatment induced [001]-preferred orientation growth in FAPbI(3) films, and passivated defects within the crystal. The photodetectors based on PEAI-AAE-treated FAPbI(3) film exhibits a fast response time of 485 mu s/525 mu s (rise time/fall time), high responsivity of 24.89 A W-1, and excellent specific detectivity of 1.56 x 10(13) Jones. Moreover, the PEAI-AAE-treated FAPbI(3) photodetector retained over 80% of its initial performance even after exposure to ambient air for over 720 h, demonstrating excellent long-term stability. This study provides a green processing method that paves the way for future commercialization of perovskite-based optoelectronic devices.