Fabrication and characterization of Al/ZnO-rGO/CuO/Cu heterojunction solar cell via FR4 substrate oxidation

This article present a low cost fabrication of zinc oxide–reduced graphene oxide/copper oxide (Al/ZnO-rGO/CuO/Cu) heterojunction solar cell, using a simple and efficient a low-temperature solution-based process. Graphene oxide (GO) synthesized through modified Hummers' method was thermally reduced to obtain reduced graphene oxide (rGO). Zinc oxide nanoparticles (ZnO) were combined with rGO to form a ZnO-rGO composite, subsequently deposited onto a chemically oxidized FR4 substrate (CuO) employing a simple and efficient spin casting method to construct the heterojunction. Detailed characterization techniques, including XRD, FTIR, Raman spectroscopy, FESEM, and EDX, confirmed the successful fabrication and structural integrity of the composite. The solar cell demonstrated a power conversion efficiency of 4.09 %, with a short-circuit current density (J sc ) of 14.12 mA/cm 2 , open-circuit voltage (V oc ) of 0.4203 V, and fill factor (FF) of 41.4 %. These results highlight the viability of Al/ZnO–rGO/CuO/Cu based heterojunction architectures as efficient, eco-friendly, and cost-effective alternatives to traditional photovoltaic devices, which are expensive, require very high processing temperatures, and involve complex fabrication requirements. This demonstrates their potential to replace silicon-based photovoltaics, which pose environmental pollution concerns. • A cost-effective Al/ZnO–rGO/CuO/Cu heterojunction solar cell was fabricated using oxidized FR4 copper-clad substrates. • ZnO–rGO nanocomposite was synthesized through a low-temperature, solution-based method. • Structural, morphological, and chemical characteristics were confirmed by XRD, FTIR, Raman, FESEM, and EDX analysis. • The fabricated device exhibited a power conversion efficiency (PCE) of 4.09 % , with Jsc = 14.12 mA/cm 2 , Voc = 0.4203 V , and fill factor = 41.4 %. • RGO incorporation enhanced electron mobility and reduced recombination losses, improving device performance. • The device demonstrates scalability and potential as a low-cost alternative to silicon-based photovoltaic technologies.