Self‐Powered Filterless Narrowband UV Photodetection Triggered by Asymmetric Charge Carrier Generation in a Wide‐Bandgap Halide Perovskite Ferroelectric

Narrowband photodetection with selective light detection in ultraviolet (UV) range is particularly pronounced in specialized applications such as targeted wavelength imaging and UV-phototherapy. In contrast to conventional strategies, ferroelectric materials with pronounced bulk photovoltaic effect (BPVE) provide a novel asymmetric carrier generation concept for achieving filterless spectrally selective photodetection. Herein, for the first time, the realization of self-powered filterless narrowband UV photodetection is demonstrated in bulk single crystals of a newly developed halide perovskite ferroelectric, 2FEA₂EA₂Pb₂Cl₁₀ (2FEEPC), which exhibits a wide bandgap of 3.36 eV and a remarkable spontaneous polarization (≈3.5 µC cm^-2). Benefiting from the strongly distorted inorganic framework with asymmetric delocalized electronic states, 2FEEPC demonstrates a highly wavelength-dependent BPVE along the polar direction, showing a high narrowband detecting performance with a response peak at UV wavelength of 355 nm and a full-width-at-half-maximum (FWHM) of ≈15 nm. More interestingly, the ferro-pyro-phototronic effect of 2FEEPC endows a colossal gain of up to 600% for photopyroelectric current. This work presents an unprecedented approach to achieve self-powered filterless narrowband photodetection, thereby shedding light on the development of photosensitive ferroelectrics for spectrally photoelectric applications.