Intrinsically Stretchable Fiber‐Shaped Solar Cells with Polymer‐Based Active Layer

Fiber‐shaped organic solar cells (FOSCs) with intrinsic stretchability show great potential in stretchable and wearable electronics applications. However, limited by the poor stretchability of small molecule semiconductors, the stretchability of FOSCs is still not satisfied. Polymerized nonfullerene acceptors with excellent photovoltaic performance are a promising strategy for preparing stretchable semiconductors and photovoltaics. Herein, an efficient polymer‐based bulk‐heterojunction blend is adopted as the photoactive material of the stretchable all‐polymer FOSCs. The fabricated all‐polymer FOSCs show superior intrinsic stretchability that remains more than 90% of the initial efficiency under the stretch strain of 50% and maintains stable performance even when undergoing hundreds of stretching–releasing cycles. By adding the third component of polystyrene‐ block ‐poly(ethylene‐ran‐butylene)‐ block ‐polystyrene (SEBS) elastomer, the stretchable all‐polymer FOSCs can endure the ultrahigh stretch strains over 80%. This study demonstrates the superior mechanical properties of the all‐polymer FOSCs and the simple yet effective strategy of SEBS additive to enhance stretchability.