Programmable Topotactic Phase Transformation of Correlated Mott Oxides toward Reconfigurable Photothermoelectric Devices

Phase engineering of correlated oxides exhibiting insulator-metal transitions (IMTs) offers a promising route to programmable device functionalities for electronic and optoelectronic applications. However, spatially precise and nonvolatile phase control for tuning properties on-demand in correlated oxides remains challenging due to strong lattice-electronic coupling. Here, we demonstrate on-device phase reconfiguration by engineering ordered, scalable multiphase domains via a topotactic transformation between correlated oxides (VO₂ and V₂O₃), directly imprinting photothermoelectric functionality. Notably, the laser-driven transformation enables in situ lithography-free patterning of VO₂ domains with high spatial resolution within a V₂O₃ matrix under ambient conditions. Structural characterizations and finite-element simulations reveal phase heterogeneity, epitaxial orientation, and lattice anisotropy of strained monoclinic VO₂ induced by lattice mismatch at the VO₂/V₂O₃ heterointerface. Temperature-dependent Raman spectroscopy confirms a thermally driven, reversible IMT in the laser-patterned VO₂ domains. Spatially resolved photocurrent mapping uncovers an emergent photothermoelectric response exclusively present in the laser-patterned VO₂ but absent in pristine V₂O₃, with polarity and magnitude consistent with a Seebeck mechanism. This work establishes a scalable and programmable strategy for phase-selective engineering in correlated oxides, with potential utility for spatially resolved energy conversion and reconfigurable optoelectronics.