Computational design of high efficiency FeSi2 thin-film solar cells

A novel PV cell structure in the form of a p–i–n construction is proposed by inserting a layer of FeSi2 between two layers of crystalline silicon. The energy band diagram and PV properties are simulated. The structure parameters, such as the thickness, doping concentration and defect density of states of each layer, are taken into account. The optimized structure with a thickness less than 1 μm shows a large open circuit voltage (Voc) of 0.68 V and a high photoelectric conversion efficiency (Eff) of 24.7%, which is significantly larger than that of the FeSi2/Si double-layer pn-heterojunction structure, and is comparable with the performance of crystalline Si solar cells with a thickness of 250 μm. The Voc and Eff increase further when replacing the crystalline Si at both sides of the FeSi2 layer with amorphous Si layers. The present work is expected to open a new avenue in developing low-cost thin film solar cells on the basis of the well established Si technology.