Preparation And Efficiency Of Sb ₂ O / Al ₂ 3 Composite Films On Crystalline Silicon Solar Cells Performance Study

Crystalline silicon (c-Si) based solar cell has achieved the highest power conversion efficiency (PCE) in all different kinds of solar cells nowadays and its technique in production is mature either. In recent years, the researches in PCE improvement in c-Si are mostly focusing on using semiconductor nanoparticles. In this paper, Sb2Ox/Al2O3 metal oxide layer were synthesized on the surface of c-Si solar cells through the chemical bath method (CBD) and sol-gel method. The structure, morphology and optical properties of the Sb2Ox/Al2O3 layer were characterized using field emission scanning electron microscope (FESEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and UV-Vis-NIR reflection absorption spectroscopy. The minority carrier lifetimes and sheet resistance of c-Si solar cell with Sb2Ox/Al2O3 layer were also measured by the measurement system for solar cell manufacturing and four-point probe. The photoelectrical properties of the c-Si solar cell with Sb2Ox/Al2O3 layer were tested using sun light source simulator, quantum efficiency test station and electrochemical workstation.First, Sb2Ox layer was synthesized on the surface of c-Si solar cells through the chemical bath method, the Sb2Ox layer and silicon substrate can form a heteroj unction after annealing at appropriate temperature. We study the effects of the different concentration of Sb(Ac)3 and the addition of surfactant on the morphology and the performance of the Sb2Ox layer. We tested the photoelectrical properties of c-Si solar cell with Sb2Ox layer, the quantum efficiency and power conversion efficiency were both improved comparing with c-Si solar cell without treatment. We use XPS analysis and electrochemical impedance spectroscopy (EIS) to prove that there existing a qusi-PN junction between Sb2Ox layer and silicon substrate where the Sb(V) ions act as an electron donors, while the Sb(â…¢) ions compensate the donor electrons. This qusi-PN junction structure also accompany with built-in electric potential that helps the transport and separation of photogenerated electrons and holes and successfully suppressed the carrier recombination.After this, we continue to deposit Al2O3 layer on the surface of Sb2Ox/c-Si solar cell by sol-gel method. The uniformity of the Al2O3 layer is excellent and the thickness of which is also under control. In order to take advantage of the benefits of Sb2Ox layer, and meanwhile reduce the side effects which include surface defect and oxygen defect, we employed Al2O3 that has excellent surface passivation properties can suppress the carrier recombination which further increase the minority carrier lifetimes. The Al2O3 layer also plays a role as antireflection layer, which could replace SiNx layer in some case that helps to simplify the experiments and save the cost.