Achieve the Full‐Wavelength Photoexcited Pyroelectricity in Perovskite Ferroelectric for Long‐Wave Infrared Detection

Ferroelectric materials have emerged as a promising class of optoelectronic candidates, due to their strong light‐polarization couplings that lead to fascinating physical attributes. Especially, photoexcited pyroelectricity originating from light‐induced variation of spontaneous polarization ( P s ) holds potentials for ultra‐broadband photodetection even up to long‐wave infrared optical region. For the first time, we present the full‐wavelength switchable photoexcited pyroelectric effects in a two‐dimensional perovskite ferroelectric, (4‐ethylanilinium) 2 (ethylammonium) 2 Pb 3 Br 10 ( 1 ), covering ultraviolet to long‐wave infrared spectral range. It is a high‐temperature ferroelectric ( T c = 390 K) with superior pyroelectricity, including large pyroelectric coefficients and figure‐of‐merits. Strikingly, robust full‐wavelength photoexcited pyroelectric responses are obtained in 1 under irradiation from ultraviolet (266 nm) to long‐wave infrared (12.5 µm) region, far beyond its intrinsic optical bandgap. These P s ‐dependent photoactivities can be electrically switched and controlled by electric poling. Thus, crystal‐based device of 1 allows ultrabroadband photodetection, as verified by highly‐sensitive response to human radiation. As the first report on full‐wavelength photoexcited pyroelectricity in perovskite ferroelectrics, our study highlights a promising strategy for new‐generation broadband optoelectronic devices.