Advancing high-efficiency, stretchable organic solar cells: novel liquid metal electrode architecture†

The development of stretchable electrodes for intrinsically stretchable organic solar cells (IS-OSCs) with both high power conversion efficiency (PCE) and mechanical stability is crucial for wearable electronics. However, research on top electrodes that maintain high conductivity and excellent stretchability has been underexplored. Herein, we introduce a novel liquid metal electrode architecture (i.e., indium/metallic interlayer/gallium, InMiG) for IS-OSCs. Thermally deposited indium significantly improves mechanical properties by dispersing stress, mitigating crack initiation and propagation within the underlying layers. The metallic interlayer enhances the electrical conductivity and wettability of gallium, enabling the formation of a smooth and uniform film. The InMiG electrode surpasses eutectic gallium-indium (EGaIn) in both electrical conductivity and adhesion energy. Notably, the IS-OSCs with InMiG electrode achieve a high PCE of 14.6% and retain 70% of their initial PCE at 63% strain, highlighting their potential for commercial use in wearable electronics.