Ultrahigh Photovoltage Generation with Lateral Gradient >5700 V cm^-1 Enabled by an Asymmetric Nanograting Structure

The strategic design of periodic microstructures composing diverse components with contrasting physical properties unlocks emerging material functionalities. Here, a laterally polar nanograting surface, fabricated through scalable nanoimprint lithography and self-aligned multi-patterning, featuring asymmetrically connected photovoltaic-active units with submicron periodicity, is presented. This asymmetric nanograting structure is enabled by upright, fin-like nano-walls that serve both as structural templates and conductive interconnects, allowing for the selective deposition of donor-acceptor heterojunctions to optimize photovoltaic efficiency while minimizing inactive areas. After deliberate optimization, such as transitioning from a spin-coated donor-acceptor bulk heterojunction to a vacuum-deposited bilayer one, the design achieves unprecedented photovoltage output, with peak values exceeding 5700 V cm^-1 in the best-performing architecture. This remarkably high-voltage output opens avenues for applications in micro-optoelectromechanical systems, facilitating in-chip powering of functional dielectrics and ultra-light electrostatic engines.