Active Material Design for Mechanically-Robust, Efficient 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) needs to 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, examples 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) controlling molecular weights (MWs) of the polymer acceptors (P_A), ii) incorporating a high-MW P_A as an electro-active additive into binary blends, and iii) enhancing molecular miscibility between donor-acceptor in their blends. With these contributions, the f-SOSCs with over 12% PCE and excellent stretchability is developed.