Predicted bulk photovoltaic effect in hydrogenated Zintl compounds

Abstract

The bulk photovoltaic effect (BPVE) is a phenomenon that 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 p–n 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 to be 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.