Single-step annealing and encapsulation for organic photovoltaics using an exothermically-setting encapsulant material

We report the use of a bisphenol A-based epoxy resin for use as an encapsulant material on bulk-heterojunction organic photovoltaic devices which, by way of an exothermic curing process, can also thermally anneal devices leading to increases in short circuit current density, fill factor and power conversion efficiency. As well as improving the electrical characteristics of devices, the encapsulant is effective as a barrier material to protect against degradation in air. The single-step process to both anneal and encapsulate devices could lead to improvements in the efficiency of commercial-level photovoltaic fabrication processes, a goal which is in keeping with the low-energy fabrication ethos of organic electronics in general.