Pyro‐Phototronic Enhanced SnO 2 /La:BFO/NiO x Gradient Heterojunctions for Zero‐Bias Imaging and Optoelectronic Logic Gates in Seawater

ABSTRACT Driven by the growing demand for multifunctional optoelectronics, photoelectrochemical (PEC) photodetectors have shown immense potential for advanced optical sensing and imaging in complex liquid environments. Herein, a zero‐bias PEC photodetector based on a SnO 2 /La:BFO/NiO x gradient heterojunction is developed. To overcome the intrinsic performance bottlenecks of BiFeO 3 , La 3+ doping and interface engineering are synergistically employed. This modification significantly enhances the spontaneous polarization, triggering a robust pyro‐phototronic effect. The coupling of this effect with the built‐in electric field efficiently drives the separation and transport of charge carriers. Consequently, operating at zero bias, the device achieves a high responsivity of 74 mA/W, a specific detectivity of 5.85 × 10 11 Jones, and rapid response times (23.05 and 25.5 ms). Notably, the device demonstrates excellent stability and enhanced photoresponse in real seawater, enabling exceptional object contour recognition in single‐pixel imaging within complex marine environments. Furthermore, the highly linear transient pyroelectric response enables the construction of reconfigurable logic gates. Both “OR” and “AND” logic operations are successfully realized on a single device by modulating illumination conditions. This work provides an energy‐saving strategy for designing advanced pyro‐phototronic devices, paving the way for next‐generation optical vision and photonic computing in extreme environments.