Enhancing the photovoltaic characteristics of organic solar cells by introducing highly conductive graphene as a conductive platform for a PEDOT:PSS anode interfacial layer

We propose a remarkably conductive polymer composite that results from highly conductive pristine graphene (PG) being doped with poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS). With the addition of PG to a PEDOT:PSS (B-PE) dispersion acting as a conductive platform, the sheet resistance can be lowered from 368.54 Ω/sq to 114.67 Ω/sq for the graphene-PEDOT:PSS (G-PE) over a bare glass substrate. Importantly, this only causes a minor decrease in optical transmittance of approximately 4.16% at 550 nm, and generates a noticeable decrease in the surface roughness profile of ~ 11.42 nm. XRD, Raman spectroscopy, and XPS analyses were used to verify that various types of chemical bonds are formed between the PG sheets and B-PE molecules. Due to these chemical interactions, a huge number of electrons are transferred from the PG sheets to the PEDOT, creating a net positive charge among the carbon atoms in the PG sheets. This results in an increase in the conductivity of the G-PE composite and, consequently, improves the power-conversion efficiency (PCE; 4.52%) of organic solar cells utilizing G-PE composite hole transport layers (HTLs). This enhancement in the PCE of G-PE HTL-based devices is compared with devices fabricated from either B-PE or PG HTLs alone, these devices achieved a PCE of only 4.18% and 3.87%, respectively.