Performance Enhancement of Organic Solar Cells by Adding a Liquid Crystalline Molecule in Cathode and Anode...

In this study, an effective and simple approach for optimizing the performance of both cathode and anode interlayers in OSCs is demonstrated using 4-heptyl-4'-cyanobiphenyl (7CB) to dope a classic cathode (ZnO and SnO₂) or an anode interlayer [poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)]. Because of the enhanced light absorption, improved physical contact between a photoactive layer and an interlayer, and increased carrier recombination, all of the devices based on a 7CB-doped interlayer show increased short-circuit current density (J_sc), fill factor (FF), and power conversion efficiency (PCE) compared to the corresponding undoped interlayer, regardless it is the anode interlayer or the cathode interlayer, which is a rare phenomenon in the interlayer modification field.