Asymmetric MXene/ZnO Heterostructures for High-Performance Self-Powered Photothermoelectric Photodetectors

Abstract Self-powered photothermoelectric (PTE) detectors are pivotal for energy-autonomous nano-optoelectronics; however, achieving high sensitivity under weak-light illumination remains a challenge due to the negligible thermal gradients (ΔT) established at low incident flux. Herein, we report a self-powered broadband PTE detector based on asymmetric Ti3C2Tx MXene/ZnO heterostructured architectures. By engineering asymmetric photothermal dissipation within the MXene layers, a temperature gradient is established across the electrode–channel interface, combined with the distinct Seebeck coefficients to generate a net potential that enables efficient zero-bias operation. To overcome the weak-light bottleneck, ZnO nanowires were integrated to induce an energy-filtering effect via band bending, which boosts the absolute Seebeck coefficient (|S|) within the channel region, thereby amplifying the overall PTE response. Consequently, the asymmetric MXene/ZnO device exhibits competitive sensitivity across the UV–Vis–NIR spectrum (365–808 nm). Specifically, under a low power density of 1 μW cm–2, the detector achieves a responsivity of 328 mA W–1 at zero bias. Coupled with a response time (τ1/τ2 = 11/13 ms), the device demonstrates multifunctional utility for energy-autonomous optical communication, flame monitoring, and precision physiological sensing. This work provides a scalable strategy for engineering thermo-optical–electrical gradients, laying a solid foundation for next-generation, high-sensitivity self-powered optoelectronic platforms.