Improved charge transport ability of polymer solar cells by using NPB/MoO3 as anode buffer layer

Abstract Efficient polymer solar cells were fabricated with regioregular poly 3-hexylthiophene (P3HT):(6,6)-phenyl C61 butyric acid methyl ester (PCBM)) as active layer and molybdenum trioxide (MoO 3 ) and (N,N′-diphenyl)-N,N′-bis(1-naphthyl)-1,1′-biphenyl-4,4′-diamine (NPB) as buffer layers. The results of transient photocurrent and electrochemical impedance spectrometry of device indicate that the insertion of NPB layer between the active layer and MoO 3 layer is critical to the enhanced performance. It can effectively prevent charge recombination at the interface of MoO 3 hole extraction layer, reduce interfacial resistance due to the formation of Ohmic contact and enhance the exciton dissociation because of the newly formed NPB/PCBM dissociation interface. The optimized thickness of NPB layer is 5 nm, resulting in maximized power conversion efficiency (PCE) of 3.94% under AM1.5G 100 mW cm −2 illumination.