Auxeticity-by-Assembly: Interlocking Modular Auxetic Metamaterials with Selectively Activatable AgNW–Graphene Oxide-EGaIn Composite Interconnects for Scalable Freeform Photovoltaic Modules

Abstract

Standardization remains a key bottleneck for scaling freeform photovoltaics beyond bespoke, cut-defined layouts, particularly when electrical interconnection must survive repeated deformation at joint hotspots. Here we introduce Auxeticity-by-Assembly—an interlocking modular auxetic metamaterial that generates reconfigurable freeform photovoltaic (PV) modules by repeating a standardized interlocking unit and choosing the assembly topology. The unit integrates rigid tiles for device mounting with compliant hinges and locking hinge joints, and incorporates a folding-enabled interconnector that routes current from perovskite mini-modules to hinge interconnect regions while mitigating strain at contacts. To wire the mechanically active joints, we develop selectively activatable AgNW–GO–EGaIn composite interconnects that combine partially embedded Ag nanowires for adhesion with graphene oxide–coated EGaIn liquid-metal particles (GO@EGaIn LMPs) for mechanically or laser-rupture-activated conduction. The interconnects enable on-demand patterning and maintain conductivity under folding and large tensile deformation. A 5 × 5 perovskite platform reaches a decimeter-scale footprint (∼900 cm2), conformally deploys on dome-like surfaces, and preserves photovoltaic I–V characteristics over repeated expansion–contraction cycles. Auxeticity-by-Assembly provides a scalable, standardized route to deployable freeform PV and other reconfigurable electronic skins.