Self-Powered Broadband Photodetection Ranging from X-ray to UV-Vis Light in a Polar Perovskite Induced by Bulk Photovoltaic Effect.

Self-powered broadband photodetection has evoked increased interest in next-generation photoelectronic devices. However, realizing self-powered broadband photodetection in a single material is still a challenge because of the harsh requirements, including powerful built-in field, excellent charge transport behaviors, as well as the broad absorption. Herein, we first realize broadband photodetection in the range from X-ray to UV-vis light in a polar two-dimensional perovskite (2-FBA)₂MAPb₂I₇ (2-FBA = 2-fluorobenzylamine, MA = methylamine) by incorporating an aromatic spacer into a three-dimensional prototype. As a result, (2-FBA)₂MAPb₂I₇ exhibited a superior response to UV-vis light (377 to 637 nm) without voltage bias. Specifically, a high switching ratio of 1.05 × 10⁴, an outstanding responsivity (R) of 1420 mA W^-1, and detectivity (D*) of 1.59 × 10¹³ Jones were achieved under light illumination at 520 nm. Moreover, (2-FBA)₂MAPb₂I₇ achieved a high sensitivity of 46.4 μC Gy^-1 cm^-2 without voltage bias, two times higher than that of a commercial α-Se film detector (20 μC Gy^-1 cm^-2). The sensitivity can be further improved to 3316 μC Gy^-1 cm^-2 at a 50 V bias. These results give insight into the design of 2D perovskites for self-powered broadband photodetection.