Intrinsically Stretchable Organic Solar Cells without Cracks under 40% Strain

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 approximate to 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.