Spinel-Type nitride compounds with improved features as solar cell absorbers

Ternary spinel nitrides are a new class of semiconductor materials with tunable bandgap in the visible range. In this work, we report a rational design of spinel-type nitride compounds with improved features as solar cell absorber materials by way of the in-gap-band (IGB) concept. For this purpose, a systematic screening on the effect of transition metal (M = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Nb, Mo) hyperdoping on the crystal and electronic structure properties of germanium (Ge) and tin (Sn) spinel nitrides (γ-(MmSnx-mGe1-x)3N4, x = 0.5, m = 0.042, 0.083) was carried out through accurate ab-initio methods. The analysis of the electronic structure reveals that M-hyperdoped ternary spinel nitrides with M = Cr, Co, Cu show an IGB with the adequate properties to allow two extra photon absorption processes. A detailed study of the sunlight absorption properties, and maximum photovoltaic efficiencies reveal that Co-hyperdoped spinel is an excellent candidate to be used in photovoltaic devices as absorber material, with maximum photovoltaic efficiency of ~ 55. Overall, our results suggest that it would be possible to design new ternary spinel-type nitride materials with improved absorption properties suitable for potential use in photovoltaic applications.