Photoactive Material Design for Intrinsically-Stretchable Polymer Solar Cells

Considering the technical standards (e.g., mechanical robustness) required for wearable electronics, which are promising application platforms for organic solar cells, the development of fully stretchable OSCs (f-SOSCs) should be accelerated. First, the mechanical requirements of f-SOSCs, in terms of tensile and cohesion/adhesion properties, are summarized along with the experimental methods to evaluate those properties. Second, important studies to make each layer of f-SOSCs stretchable and efficient are discussed, emphasizing strategies to simultaneously enhance the photovoltaic and mechanical properties of the active layer. For example, I present material design strategies to enhance the mechanical robustness of the PSCs as well as their power conversion efficiencies (PCEs); i) incorporating a high-molecular weight polymer acceptor as an electro-active additive into binary blends, ii) design of hydrogen-bonding incorporated polymers, and iii) design of block copolymerized electroactive polymers. With these contributions, the f-SOSCs with over 14% PCE and excellent stretchability are developed. In addition, I will present the example of strain-induced power enhancement using these f-SOSCs.