Mechanically-durable high performance OPVs using semi-interpenetrating networks

Organic photovoltaic (OPVs) devices offer a number of unique advantages over conventional single crystal silicon solar cells, including simple and low-cost fabrication and reduced weight. However, OPV devices exhibit poor durability to mechanical deformations. Here, we study the use of an elastic semi-interpenetrating network to improve the mechanical durability of the active layer of OPV devices based on the high-performance PBDBT-2F:ITIC donor:acceptor blend. The elastic interpenetrating network is synthesized in situ after solution deposition of the donor:acceptor blend along with reactive thiol-ene small molecules. We systematically investigate the effects of strain on the network-stabilized active layer structure and show that network-stabilized devices outperform pristine devices above a critical bending strain and number of bending deformations. The elastic interpenetrating network suppresses crack formation and improves durability to high-curvature and repeated bending deformations. This work describes a general route to high performance flexible devices and detailed design parameters that influence performance.