Optical properties and carrier transport in c‐Si/conductive PEDOT:PSS(GO) composite heterojunctions

We investigated the crystalline silicon (c-Si)/conductive poly(ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS):graphene oxide (GO) composite heterojunction devices with optical characterization and carrier transport measurement techniques. The optical transmittance in the UV region also decreased markedly for the films with GO content above 20 wt%, whereas it increased markedly in the visible-infrared regions. The solar cell devices consisting of spin-coated PEDOT:PSS(GO) composite on n-type c-Si(100) wafer exhibited a maximum efficiency of 10.3%, a short-circuit current Jscof 28.9 mA/cm2, a open-circuit voltage Voc of 0.548 V, and a fill factor FF of 0.675 at a GO content of 12.5 wt%. The ideality factor deduced from current density-voltage (J -V) plots in the dark increased with GO content from 1.12 for pristine PEDOT:PSS to 2.91. Temperature-dependent dark J -V measurements suggest that the carrier transport in the devices is controlled by diffusion and recombination in the space-charge region for the devices. The role of the GO addition into conductive PEDOT:PSS is demonstrated for the c-Si(100)/PEDOT:PSS(GO) composite junction solar cells in terms of the optical and carrier transport properties. (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)