Simultaneous Integration of Poly(dimethylsiloxane) Elastomer in Polymer Donor and Dimer Acceptor Enables Strain-Induced Power Enhancement in Intrinsically-Stretchable Organic Photovoltaics

Abstract

Intrinsically-stretchable organic solar cells (IS-OSCs) are an emerging class of wearable power sources owing to their ability to stretch in multiple directions. However, their current stretchability remains insufficient to meet the demands of wearable electronics. In this study, we develop a poly(dimethylsiloxane) (PDMS)-incorporated dimer acceptor (DYPDMS) and a PDMS integrated block-copolymer donor (PM6-b-PDMS) to achieve IS-OSCs with a high power conversion efficiency (PCE= 12.7%) and remarkable mechanical stretchability, maintaining over 80% of their initial PCE under 40% strain. Notably, we demonstrate the critical role of simultaneously integrating PDMS into both the polymer donor (PD) and acceptor materials to achieve superior photovoltaic and mechanical performance in IS-OSCs. The dual incorporation of PDMS significantly enhances the blend morphology by improving the thermodynamic compatibility between the PM6-b-PDMS PD and the dimer acceptors while effectively suppressing macrophase separation of PDMS elastomers from the photoactive materials. Consequently, IS-OSCs based on the PM6-b-PDMS:DYBT:DYPDMS system achieve significantly higher PCE and stretchability compared to systems using PM6-b-PDMS:DYBT (without PDMS in dimer acceptors) or PM6-b-PDMS:DYBT:PDMS (with PDMS physically mixed). Importantly, these IS-OSCs exhibit an increase in overall power output under stretching up to 35% strain, demonstrating a successful example of IS-OSCs with strain-induced power enhancement.