Performance optimization of silicon homojunction solar cells through aging-controlled spin-coated ZnO ARC layers

Abstract ZnO is crucial for improving the efficiency of silicon homojunction solar cells, owing to its remarkable optical transparency, elevated refractive index, and broad band gap. When applied as an antireflection coating (ARC), ZnO significantly reduces front-surface reflection and enhances light coupling into the silicon absorber layer. In this study, the structural, optical, and antireflective properties of ZnO thin films, employed as ARCs, were systematically investigated with respect to solution aging temperature during spin coating. The primary aim was to elucidate how this processing parameter influences the performance of silicon homojunction solar cells. Precursor solutions were aged at three distinct temperatures (25 °C, 50 °C, and 75 °C) prior to deposition. The resulting ZnO films were comprehensively characterized using X-ray diffraction (XRD), UV–vis spectrophotometry, atomic force microscopy (AFM), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and Raman spectroscopy, to assess changes in crystallinity, surface morphology, transmittance, and thickness. To evaluate photovoltaic performance, the ZnO-coated silicon homojunction solar cells were modeled using the SCAPS-1D simulation program. The results reveal that increasing the aging temperature enhances film uniformity, grain size, and optical band gap, which in turn improves light transmission and reduces optical losses at the front surface. Notably, ZnO films aged at 75 °C exhibited the highest transmittance, leading to a significant enhancement in short-circuit current density (J sc ) and an approximate 7.5% increase in power conversion efficiency (PCE) compared to lower-temperature counterparts. This work highlights the critical role of solution aging in tailoring ZnO ARCs, offering a simple, scalable, and cost-effective strategy to boost the performance of Si-based homojunction solar cells through optimized light management.