Use of modified PEDOT:PSS/Graphene oxide dispersions as a hole transport layer for inverted bulk-heterojunction organic solar cells

The thin-film fabrication of PEDOT:PSS-based dispersions via solution-processing techniques is critical to developing a hole transporting layer (HTL) for inverted organic photovoltaic (iOPV) devices. However, the highly hydrophilic nature of PEDOT:PSS solutions is a drawback that strongly inhibits their usage as HTLs in iOPV devices. In this study, the hydrophilic nature of PEDOT:PSS solutions was tuned successfully using various solvents and surfactants. Additionally, the dispersion of graphene oxide (GO) colloidal suspensions within the PEDOT:PSS was used to enhance the electrical conductivity of the PEDOT:PSS. These modifications have the benefit of enabling effective coating of a PEDOT:PSS/GO blend as an HTL on top of a hydrophobic photoactive layer, resulting in a homogeneous, conductive thin film for iOPV devices. In order to further optimize the ratio of PEDOT:PSS to GO, the effect of the GO dosage is investigated systematically, which demonstrated the influence of this ratio on the overall power conversion efficiency of devices. The results demonstrate that the additive- and GO-modified PEDOT:PSS can lead to enhancement of device efficiency, mainly due to enhanced HTL film morphology, high electrical conductivity, high adhesiveness, and well-matched bandgap energy. We believe that the modified PEDOT:PSS/GO is a prospective candidate for utilization in the HTL for iOPV devices in nextgeneration energy conversion applications and other potential energy management devices.