Polycrystalline formamidinium lead bromide (FAPbBr3) perovskite as a self-powered and fast visible-light photodetector

Halide perovskite compounds have become a major research topic in the semiconductor field due to a variety of optoelectronic applications and their advantage of low-cost and simple processing methods, combined with tunable properties. The current work presents the use of (NH2)2CHPbBr3 (FAPbBr3), with a direct band gap of 2.17 eV, as a robust visible-light detector. The polycrystalline material was prepared by fusion of the precursor compounds PbBr2 and (NH2)2CHBr in solid state. It was then pressed in the form of a pellet and two transparent fluorine-doped tin oxide glasses were attached on both sides. The photodetector selectively responds to photon energies exceeding its band gap even without external bias, operating in an energy-efficient, self-powered mode. The response times to pulsed light are orders of magnitude shorter than these of previously reported FAPbBr3- based detectors. Electrochemical impedance spectroscopy determined in depth the electrical characteristics of the semiconducting perovskite with and without illumination. These results provide evidence that polycrystalline FAPbBr3, obtained with low-cost and simple synthetic methods compared to other forms, can be an excellent candidate for fast and self-powered optoelectronics, useful for Visible Light Communication (VLC) and Internet of Things (IoT) systems.