The effects of contact barrier height on performances of Si/BaSi2 p–n heterojunction, BaSi2 p–n homojunction and Si/BaSi2/Si p–i–n heterojunction were numerical calculated. Band energy diagram, built-in electric field, carrier generation and carrier transportation distributed in the devices are comprehensively investigated. BaSi2 p–n homojunction solar cells are very sensitive to front contact barrier height due to the high light absorption coefficient of front p-BaSi2 layer. Si/BaSi2 p–n heterojunction and BaSi2 p–n homojunction solar cells with donor concentration (ND) less than 1017 cm−3 are apparently affected by back contact barrier height. The ideal α-Si/BaSi2/α-Si p–n solar cell achieves a high Voc of 1.131 V, suggesting a promising and alternative structure to gain excellent BaSi2-based solar cells once the Urbach tail states and defects can be effectively eliminated. The results help to fundamentally understand operation mechanism and provide intuitive guidance for achieving high-efficiency BaSi2 solar cells.
