Coupled ZnO–SnO₂ Nanocomposite for Efficiency Enhancement of ZnO–SnO₂/p-Si Heterojunction Solar Cell

This article presents a low-cost fabrication of binary/coupled ZnO–SnO2composite semiconductors for heterojunction solar cells using a simple and effective sol-gel approach. Here, the synthesis and characterization of coupled ZnO–SnO2nanocomposites are carried out with varied stoichiometry designated as ZnO–SnO2(20:80), ZnO–SnO2(50:50), and ZnO–SnO2(80:20). The X-ray diffraction (XRD) spectra confirmed an excellent crystalline domain in the order of ZnO–SnO2(80:20) > ZnO–SnO2(50:50) > ZnO–SnO2(20:80). Nanorods formation of ZnO–SnO2has been confirmed through the scanning electron microscopy (SEM) micrograph. The improvement in photoconversion efficiency of solar cell from 3.39% to 3.98% was achieved due to increasing photo-excited free carrier generation with a significant change of nanorods dimensions. Furthermore, the UV–vis spectroscopy exhibited impressive transmittance of 85% in the wavelength range of 200–1000 nm. A bandgap modulation of 3.66–3.40 eV has been achieved. The power conversion efficiency (PCE) of 3.98 (Jsc = 18.83mA/cm2,Voc = 0.581V, and FF = 36.37) is determined using ZnO–SnO2(80:20), which is almost twice of that of a single semiconductor-based Al/ZnO/p-Si/Al solar cell.