Polycrystalline formamidinium lead bromide (FAPbBr

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 (NH 2 ) 2 CHPbBr 3 (FAPbBr 3 ), 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 PbBr 2 and (NH 2 ) 2 CHBr 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 FAPbBr 3 -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 FAPbBr 3 , 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. Display Omitted • Polycrystalline FAPbBr 3 is prepared by fusion of PbBr 2 and FABr in solid state. • The FTO/FAPbBr 3 /FTO photodetector shows high selectivity in the range 500–600 nm. • The device operates as an energy-efficient, self-powered photodetector. • Orders of magnitude shorter response times compared to other FAPbBr 3 photodetectors.