A method for evaluating spectral down-shifting materials applied to solar cells

Abstract

Spectral down-shifting materials convert the photons in the solar spectrum that are less efficiently utilized into photons that can be fully used by solar cells, providing an attractive idea for improving the photoelectric conversion efficiency (PCE) of the solar cells. However, there is currently no parameter that can reliably assess the photoelectric excitation effect of the down-shifting materials on solar cells. Here, a calculation method that can reliably evaluate the photoelectric excitation effect of the down-shifting materials on the solar cells is proposed, which introduces the solar spectrum, the quantum yield of materials, and the external quantum efficiency of the solar cells. Then, the calculation method is described in detail with the relevant physical processes, taking the down-shifting materials acting on crystalline silicon solar cells as an example. Finally, the Pearson correlation coefficient between the parametric photoelectric excitation efficiency (PEE) calculated using the method and the ΔPCE value obtained experimentally was 0.999 51, demonstrating the reliability of the calculation method. The PEE calculated using this method is an inherent property of the down-shifting material for a specific solar cell and does not change with external conditions. Therefore, PEE can be used as a parameter for down-shifting materials to facilitate the selection of materials with better effects on solar cells from an enormous number of down-shifting materials and is suitable for various types of solar cells.