Enhancing light absorption and lifetime stability of organic solar cells using pentacene encapsulation

Abstract

. In the present work we compare the performance of a pristine P3HT:PCBM based bulk heterojunction solar cell with a device incorporated with pentacene encapsulated Ag nanoparticles. Encapsulation has been achieved through thermal evaporation of a 22 nm pentacene thin film. Introduction of pristine Ag nanoparticles revealed better overall performance with a 22% increase in photo-conversion efficiency. This is attributed to the localized surface Plasmon effect by Ag nano-islands. A study of device lifetime showed that despite the efficiency enhancement, the device drastically degraded upon exposure to air. Encapsulating Ag nanoparticles with pentacene increased light absorption and device stability but traded off photo-conversion efficiency. This long lifetime could be as a result of silver passivation by pentacene which minimizes oxidation of Silver nanoparticles and etching of the ITO electrode by the acidic PEDOT:PSS.