The manageable formation of the gradient‐layered polymer/fullerene blend films via the addition of bathocuproine and their applications in organic solar cells

Abstract

AbstractWe report the manageable formation of the gradient‐layered poly(3‐hexylthiophene) and [6,6]‐phenyl C61‐butyric acid methyl ester (P3HT/PCBM) blend film by spin coating via introducing bathocuproine (BCP) into the mixed P3HT/PCBM solution. The BCP can improve the aggregation and thereby the preferential precipitation of PCBM during the spin‐coating process, leading to the gradient‐layered phase separation of P3HT and PCBM. The regular solar cells using the gradient‐layered ternary blend films gave poor photovoltaic performance, due to the mismatch between the polarity of the regular‐device structure and the vertical composition profile of the ternary blend film. By contrast, in the inverted solar cell, the gradient‐layered ternary blend film could provide the increased device performance over the conventional bulk heterojunction binary blend films.