Photoexcited Ultraviolet‐to‐Infrared (II) Pyroelectricity in a 2D Ferroelectric Perovskite Driving Broadband Self‐Powered Photoactivities

Abstract Photoexcited pyroelectricity in ferroelectrics allows the direct conversion of light radiation into electric signal without external power source, thus paving an avenue to promote optoelectronic device performances. However, it is urgently demanded to exploit new ferroelectrics with this attribute covering ultraviolet (UV)‐to‐infrared (IR) region for self‐powered photodetection. Herein, broadband light‐induced pyroelectric effects in a new 2D perovskite‐type ferroelectric, (BBA)2(EA)2Pb3Br10 (1; BBA = p‐bromobenzylammonium, EA = ethylammonium), showing a high Curie temperature of 425 K and notable pyroelectric coefficient (≈5.4 × 10⁻³ µC cm⁻² K⁻¹) is presented. Especially, photo‐induced change of its electric polarization leads to ultraviolet‐to‐infrared pyroelectricity in a wide spectral region (377–1950 nm). Broadband photoactivities actualized by this property break the limitation of its optical bandgap. Thus, single‐crystal detectors of 1 are sensitive to UV‐to‐IR light with a small temperature fluctuation of 0.3 K, exhibiting a high transient responsivity up to ≈0.28 mA W⁻¹ and specific detectivity of 1.31 × 10¹⁰ Jones under zero bias (at 405 nm); such figure‐of‐merits are beyond than those self‐powered photodetectors using oxide ferroelectrics. It is anticipated that the findings of light‐induced pyroelectricity afford a feasible strategy to assemble newly‐conceptual smart photoelectric devices, such as self‐powered broadband detectors.