Reconfigurable MoTe ₂ Homojunctions via Ultraviolet-Light Assisted Doping for Self-Powered Voltaic Devices

The development of adaptive photovoltaics capable of dynamically optimizing energy harvesting under varying illumination conditions has driven significant interest in reconfigurable p–n junctions. This study presents a tunable homojunction photovoltaic device fabricated from a single ambipolar MoTe 2 flake. Through the integration of a hexagonal boron nitride (h-BN) dielectric layer and localized ultraviolet (254 nm) photodoping, we achieve spatially selective and fully reversible n-type and p-type doping within the same material platform. This approach enables the in situ formation of both p–n and n-p junctions with high precision and stability. Electrical characterization under dark conditions reveals excellent diode behavior, with rectification ratios reaching 2.2 × 10 3 and 1.3 × 10 3 for p–n and n–p configurations, respectively. Under 450 nm visible illumination at zero bias, the device exhibits prominent photovoltaic characteristics, including a power conversion efficiency of 0.5%, an open-circuit voltage of 0.427 V, and a fast photoresponse with a rise time below 2 ms. Light intensity-dependent measurements further reveal that the short-circuit current follows a near-ideal power-law dependence on incident light power density, yielding a maximum output power of 2.9 pW. The capability to dynamically reconfigure junction polarity and optoelectronic characteristics through photodoping underscores the potential of two-dimensional materials for self-optimizing optoelectronic systems. This work provides a feasible strategy for designing adaptive, self-powered photonic devices with in situ tunability, offering new avenues for intelligent energy harvesting and responsive sensor applications.