Transforming III-V binaries into stable ternary materials for solar cells applications

Abstract

The world speedily growing energy demand motivates vivid interest and intensive searching new optimal direct bandgap materials for efficient thin-film photovoltaic cell devices. Here, we present solar cell materials search using density functional theory and ab initio evolutionary algorithm. The compounds in focus belong to cationic ternary III-V family. It is found that AlGaN2 (P3m1), InGaN2 (P3m1), AlGaP2 (P4‾ m2) InGaP2 (R3m), AlGaAs2 (R3m) and InGaAs2 (R3m and P4‾ m2) are weakly unstable (enthalpy of formation between 4 and 76 meV) with respect to decomposition, the vibrational calculations divulge that these materials should be synthesized under moderate growth temperature. Moreover, phonon dispersion and elastic constants calculations evince dynamical and structural stability of these compounds.Accurate electronic band structures evidence that most of the ternary III-V materials are semiconductors with direct bandgaps except AlGaP2 that is found indirect. Based on the metric of spectroscopic limited maximum efficiency, solar cell efficiency of AlGaAs2, InGaAs2 (R3m), InGaP2, InGaN2, and InGaAs2 (P4‾ m2) is predicted respectively to be 24%, 24.6%, 25.9%, ∼30% and ∼30.6%, which exceeds those of materials currently used as absorber layer.