Poly(dimethylsiloxane)-Incorporated Block Copolymer-Typed Donor for High Performance and Stretchable Solar Cell

High efficiency and superior stretchability are the dual key factors of polymer solar cells (PSCs) for an energy supplier of wearable devices. The popular polymer donors (PDs) and small molecule acceptors (SMAs) comprising an active layer of PSC exhibit rigid structures for higher optoelectrical properties but simultaneously show inferior mechanical robustness. In this regard, block copolymer (BCP) consisting of conjugated PD block and flexible elastomer block can address this inferior stretchability by utilizing the stretchability of flexible elastomer without phase separation between the elastomer and other components. Thus, we designed PD (PM6)-b-Poly(dimethylsiloxane) (PDMS)-typed tri-BCP as the PD to realize highly efficient and stretchable PSCs. Additionally, PM6-b-PDMS with different PDMS blocks were further compared. We find that PM6-b-PDMS typed tri-BCP showed higher efficiency (> 17.5%) and 12-fold higher mechanical robustness (toughness of PM6-PDMS19:L8-BO= 5.60 MJ m−3) compared to the reference PM6:L8-BO blend films (toughness= 0.45 MJ m−3). Interestingly, PM6:L8-BO:PDMS ternary blend showed much lower efficiency (4.13%) and mechanical robustness (0.07 MJ m−3) than the previous two blends. This study implies the importance of the utilization of elastomers by the tri-BCP method to realize high-performance and mechanically robust PSCs.