High‐Performance Photodetectors with Broad and High Operating Temperature Driven by Ferroelectric Phase Separation

The linear response of photodetectors decreases at high temperatures, which highlights the need for breakthroughs over a wide temperature range. The solid solution photodetectors (1− x )K 0.5 Bi 4 . 5 Ti 4 O 15 ‐ x BaTiO 3 ( x = 0.0, 0.04, 0.06, 0.08, 0.10, 0.12), including tetragonal/orthorhombic ferroelectric phase separation are synthesized, which realizes self‐powering and fast response. The performance fluctuation of <5% within the temperature range of 25–200 °C is achieved in x = 0.1 photodetectors under 356 nm illumination, including a responsivity of 0.15 A W −1 , specific detectivity of 7.95 × 10 11 Jones, and a high external quantum efficiency of 13.9%. The phase boundary and mosslike fine‐grain structure boost the heat transfer, which significantly enhances the high‐temperature stability of UV detection. These results provide guidelines for high‐performance self‐powered UV photodetectors suitable for high‐temperature environments.