Realization of Evaporated Electrode-Based Intrinsically Stretchable Ternary Organic Solar Cells through Encapsulation Strategy

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