Interface investigation and engineering - achieving high performance polymer photovoltaic devices

The contact between the polymer active layer and the electrode is one the most critical interfaces in polymer solar cells. In this article, we report the progress of interface engineering in polymer solar cell research, where the multiple functions of the interfacial materials will be discussed. The vertical composition profile in polymer: fullerene blends is an emerging topic, and the interlayer effect on the vertical phase separation and device performance will be highlighted. We also discuss the energy level alignment at the bulk heterojunction (BHJ) interface, with the aim of providing a better understanding towards the route of high efficiency polymer solar cells.