High-Performance Photodiode-Type Photodetectors Based on Polycrystalline Formamidinium Lead Iodide Perovskite Thin Films

Photodetectors based on three dimensional organic-inorganic lead halide perovskites have recently received significant attention. As a new type of light-harvesting materials, formamidinium lead iodide (FAPbI(3)) is known to possess excellent optoelectronic properties even exceeding those of methylammonium lead iodide (MAPbI(3)). To date, only a few photoconductor-type photodetectors based on FAPbI(3) single crystals and polycrystalline thin films in a lateral structure have been reported. Here, we demonstrate low-voltage, high-overall-performance photodiode-type photodetectors in a sandwiched geometry based on polycrystalline alpha-FAPbI(3) thin films synthesized by a one-step solution processing method and post-annealing treatment. The photodetectors exhibit a broadband response from the near-ultraviolet to the near-infrared (330-800 nm), achieving a high on/off current ratio of 8.6 x 10(4) and fast response times of 7.2/19.5 mu s. The devices yield a photoresponsivity of 0.95 AW(-1) and a high specific detectivity of 2.8 x 10(12) Jones with an external quantum efficiency (EQE) approaching 182% at -1.0 V under 650 nm illumination. The photodiode-type photodetectors based on polycrystalline alpha-FAPbI(3) thin films with superior performance consequently show great promise for future optoelectronic device applications.