Realization\nof Evaporated Electrode-Based Intrinsically\nStretchable Ternary Organic Solar Cells through Encapsulation Strategy

The mechanical properties of organic solar cells are\nof great importance\nto ensure their application in wearable or stretchable electronics.\nHere, we introduce polymer acceptor (N2200) into the active layer\nblend, and realize intrinsically stretchable organic solar cells (<i>is</i>-OSCs) with evaporated electrode via encapsulation strategy.\nThe incorporation of N2200 simultaneously enhances the mechanical\nstretchability and PCE of <i>is</i>-OSCs, attributed to\nthe enhanced polymer chain entanglement, and N2200 can act as tie\nmolecules to provide electric connection among small molecule domains.\nMore importantly, encapsulating the evaporated electrode-based <i>is</i>-OSCs leads to significant improvement in its mechanical\nstretchability, with 80% PCE retention under a large strain of 20%,\ncompared to <2.5% strain for the unencapsulated ones. Additionally,\nencapsulated <i>is</i>-OSCs retained 67% PCE after 1000\ntest cycles at a stretch strain of 15%, whereas unencapsulated devices\ncan only retain 33% PCE after 200 test cycles under a small strain\nof 5%.