Low-temperature thermal nanoimprint lithography of anti-reflective structures for flexible low band gap organic solar cells

摘要

The effect of adding anti-reflective structures to a PCPDTBT: PCBM organic solar cell on a flexible substrate using a one-step thermal-nanoimprint lithography process has been studied. In order to process nanostructures onto polyethylene terephthalate (PET) substrates, a low glass transition polymer was used. The power conversion efficiency (PCE) was increased by 4% when the light was irradiated at normal incidence. However, at oblique angles of incidence (80°), a 32% relative increase in PCE was observed showing the enhanced light-capturing capability of the anti-reflective features. This efficiency enhancement was attributed to reduced reflection at the air-PET interface, which is supported by optical modelling data.