Thermoplastic elastomer enhanced interface adhesion and bending durability for flexible organic solar cells

Stable interface adhesion and bending durability of flexible organic solar cells (FOSCs) is a basic requirement for its real application in wearable electronics. Unfortunately, the device performance always degraded during continuous bending. Here, we revealed the weak interface adhesion force between MoO 3 hole transporting layer (HTL) and the organic photoactive layer was the main reason of poor bending durability. The insertion of an interface bonding layer with a thermoplastic elastomer, polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene (SEBS) effectively improved the interface adhesion force of MoO 3 HTL and the active layer and decreased the modulus, which ensured higher than 90% of the initial efficiency remaining after 10000 bending. Meanwhile, the FOSCs gave an efficiency of 14.18% and 16.15% for the PM6:Y6 and PM6:L8-BO devices, which was among the highest performance of FOSCs. These results demonstrated the potential of improving the mechanical durability of FOSCs through thermoplastic elastomer interface modification.