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)₂Pb₃Br₁₀ (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.