Intrinsically Stretchable Organic Solar Cells without Cracks under 40% Strain

Abstract Intrinsically stretchable organic solar cells (IS‐OSCs) have been recently spotlighted for their omnidirectional stretchability, seamless integrability to any surface, and facile fabrication. Due to these attributes, IS‐OSCs are ideal off‐grid power sources, especially for wearable electronics in real‐life. However, under human body elongation as high as ≈40%, cracks in IS‐OSCs are considered inevitable, and the origin of the mechanical failure is rarely identified. Herein, the crack‐initiation and the propagation mechanism are first clarified. Based on this, a crack‐free substrate/transparent electrode platform for stretchable electronics is also suggested. A double‐locking scheme, which reinforces the physical/chemical adsorption within the most mechanically fragile layer, a poly(3,4‐ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) and also with thermoplastic polyurethane substrate, is introduced. As a result, the crack‐onset strain of double‐locked IS‐OSCs surpasses 40%, while that of pristine ones is less than 20%. The IS‐OSCs with the double‐locked system exhibits an efficient power conversion efficiency of 10.2%, and the absence of cracks allows the IS‐OSCs to maintain 79.7% of the initial PCE at 40% strain.