Predicted bulk photovoltaic effect in hydrogenated Zintl compounds

The bulk photovoltaic effect (BPVE) is a phenomenon which creates a net electrical current from sunlight in a polar noncentrosymmetric material possessing a moderate band gap. This effect is being explored as an alternative to traditional pn-junction solar cells to convert solar energy into electricity. This paper assesses the possibility that hydrogenated Zintl-phase compounds consisting only of metal, metalloid, and hydrogen atoms, may be able to provide a BPVE response. Towards this end, the magnitude of the BPVE shift current is calculated for each of the compounds AeTrTtH (Ae = Ca, Sr, and Ba; Tr = Al and Ga; and Tt = Si, Ge, and Sn). For this family of hydogenated Zintl compounds, maximum shift current responses are predicted that are up to eight times greater than that calculated for BiFeO3, and have a significant response down to much lower photon energies than BiFeO3 as well. With band gaps below 1 eV, and with some members of this family of compounds exhibiting stability in air up to 770 K, some of these compounds may find use in photovoltaic devices.