The Fabrication of High Efficiency Perovskite/Crystalline Silicon Tandem Solar Cells

Crystalline silicon (c-Si) solar cells have dominated the photovoltaics market for decades, with a current market share of about 90%. However, to make photovoltaics fully competitive with conventional energy sources, further progress toward ultrahigh efficiency low-cost solar modules is required. Recently, the success of organic–inorganic halide perovskite solar cells provides a potential in combining existing high-efficiency c-Si solar cell to form a low-cost high-efficiency tandem solar cell. It is known that it should be followed some design guidelines to achieve a high efficiency tandem cell. The first one is lattice match to reduce defect formation. The second one is current match to avoid the excess current causes the heat generation. The third is bandgap match to absorb the whole light spectrum. The forth is tunnel junction that provide a current path for the reverse p-n junction in tandem cells. In this project, we will investigate the perovskite/c-Si tandem cells. Perovskite and silicon are different materials. It is difficult to achieve the lattice match between them. But, we can reduce the defect formation by passivation. For current matching, we can do some experiments to know the efficiency of silicon solar cells under different light intensity and tune the top cell to match it. The energy bandgap of perovskite material is tunable by adjusting the ratio of iodine and bromine. We will use the transparent conductive oxide, ITO, as a tunnel junction between the top and bottom cells. In literatures, it had been reported that the efficiency of tandem cells is very low due to parasitic absorption in the top cell in the visible spectral region but even more in the infrared spectral region. Thus, in this project, we will systematically study to reduce the shadowing effect and parasitic absorption in top cells. This project will be finished in two year. In the first year, we investigate the transmission characteristics of perovskite solar cells to optimize the cell preparation parameters, such as thickness of perovskite absorption layer, electrode thickness, the selection of electron/hole transport layer for high transmission, .etc, to match the current for achieving high efficiency tandem solar cells. In the second year, we will adjust the ratio of iodine and bromine to obtain an optimal bandgap of 1.7eV in top cells. Further, we use the incorporation of Au nano-particle on the cell surface to reduce the light reflective loss and enhance light scattering. Through these efforts, we can obtain a low cost and high efficiency perovskite/c-Si tandem cells.

Project ID:PB10408-5761
External Project ID:MOST104-2221-E182-071