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 (VO 2 and V 2 O 3 ), directly imprinting photothermoelectric functionality. Notably, the laser-driven transformation enables in situ lithography-free patterning of VO 2 domains with high spatial resolution within a V 2 O 3 matrix under ambient conditions. Structural characterizations and finite-element simulations reveal phase heterogeneity, epitaxial orientation, and lattice anisotropy of strained monoclinic VO 2 induced by lattice mismatch at the VO 2 /V 2 O 3 heterointerface. Temperature-dependent Raman spectroscopy confirms a thermally driven, reversible IMT in the laser-patterned VO 2 domains. Spatially resolved photocurrent mapping uncovers an emergent photothermoelectric response exclusively present in the laser-patterned VO 2 but absent in pristine V 2 O 3, 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.