Stretchable All-Small-Molecule Organic Solar Cells Enabled by Polymer Elastomer Confinement

Intrinsic stretchability is a promising attribute of polymer organic solar cells (OSCs). However, rigid molecular blocks typically exhibit poor tensile properties, rendering polymers vulnerable to mechanical stress. In this study, we introduce a different approach utilizing all-small-molecule donors and acceptors to fabricate stretchable OSCs. An elastomer, styrene-b-ethylene-butylene-styrene (SEBS), was embedded to modulate film crystallization and stretchability. SEBS effectively confines the growth process of donors and acceptors, leading to enhancement of the crystallization quality, thus contributing to enhanced device efficiencies. Meanwhile, SEBS can absorb and release mechanical stress during stretching, thereby preventing mechanical degradation of donors and acceptors. The mechanical properties of the OSCs were significantly improved by the incorporation of SEBS. Notably, the crack-onset strain increased from 1.03% to 5.99% with SEBS embedding. These findings present a straightforward strategy for achieving stretchable OSCs using all small molecules, offering a different perspective for realizing stretchable devices.