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-SnO2 composite semiconductors for heterojunction solar cells using a simple and effective sol-gel approach. Here, the synthesis and characterization of coupled ZnO-SnO2 nanocomposites 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-SnO2 has 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 (J(sc) = 18.83 mA/cm(2), V-oc = 0.581 V, 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.