Bandgap engineering of PEDOT:PSS/rGO a hole transport layer for SiNWs hybrid solar cells

Silicon nanowire (SiNW) hybrid solar cell has been fabricated using PEDOT:PSS and rGO-PEDOT:PSS as the organic hole transport layer. The electrical characterization of the as-fabricated solar cell was done by both dark and photo J-V characteristic curves. Vertically aligned arrays of SiNWs have been synthesized by following the electroless metal-assisted chemical etching method, as confirmed by both the scanning electron microscopy and atomic force microscopy images. The structural properties of SiNWs, PEDOT:PSS and rGO-PEDOT:PSS were characterized with the help of X-ray diffraction and Raman characterization techniques. The bandgap of PEDOT:PSS comes out to be 1.77 eV as obtained from the UV-visible and photoluminescence spectra. In addition, the bandgap of PEDOT:PSS was 1.76 eV and for reduced graphene oxide (rGO) it was 0.04 eV, as obtained from the cyclic voltammetry curve. rGO-PEDOT:PSS heterojunction showed excellent J-V characteristic property in the dark and under the illumination of 1 sun. Hence the incorporation of rGO in PEDOT:PSS can improve the photovoltaic properties by increasing the conductivity of the hole transport layer, making a good interface between organic-inorganic heterojunction as well as by reducing the recombination of electron-hole pairs.