Graphene oxide/PEDOT:PSS and reduced graphene oxide/PEDOT:PSS hole extraction layers in organic photovoltaic cells

Abstract

A comparison was made between the use of graphene oxide (GO)/poly(ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) and reduced graphene oxide (rGO)/PEDOT:PSS as a hole extraction layer (HEL) in organic photovoltaic (OPV) cells. Hydrazine hydrate (HYD) and the thermal method were adopted to change the GO to rGO. The OPV cell with the GO (∼2 nm)/PEDOT:PSS HEL exhibits a power conversion efficiency (PCE) as high as 3.53% under 100 mW/cm 2 illumination and air mass conditions, which is higher than that of the OPV cell without the HEL, viz. 1.78%. The device with the PEDOT:PSS/GO HEL shows a similar PCE of 3.48%. However, the PCE of the OPV cell with the rGO/PEDOT:PSS HEL is not high as those of the cells with the HYD-rGO/PEDOT:PSS and T-rGO/PEDOT:PSS, viz. 3.3 and 3.37%, respectively. The work function of GO was 4.7 eV, but those of HYD-rGO and T-rGO were 4.2 and 4.5 eV, respectively, suggesting that the decrease of the barrier height between GO and active materials is higher than that in rGO case. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.