Effect of zinc oxide electron transport layers on performance and shelf life of organic bulk heterojunction devices

Bulk heterojunction organic photovoltaic devices with a low work function cathode often suffer from rapidly degraded performance when exposed to ambient environment. Here, we report improved performance in blended PCBM:P3HT photovoltaic devices with the addition of a combination of zinc oxide nanoparticles infiltrated with a sol-gel zinc oxide thin film as the electron transport layer. Furthermore, the zinc oxide electron transport layer dramatically improves device shelf life for unencapsulated devices tested and stored under ambient conditions. Transmission electron microscopy results help shed light on the origin behind the improved device stability. © 2011 American Chemical Society.