Ground state electronic structure, optical and thermoelectric response of Zintl phase MgAl2X2 (X= C, Sb) for renewable energy applications

Zintl compounds have gained exceptional interest in optoelectronic and thermoelectric applications. The present work includes the detailed study of electronic, optical and thermal response of Zintl phase MgAl2X2 (X = C, Sb) under the umbrella of density functional theory (DFT). Generalized gradient approximation (GGA) and modified Becke-Johnson (mBJ) potentials are used to determine the exchange-correlation potential. The structures are optimized and the stability is achieved with formation energy. An indirect bandgap of 2.74eV is observed in MgAl2C2 with mBJ potential whereas MgAl2Sb2 shows a metallic nature. The optical response of both compounds is calculated which confirms the potential of MgAl2C2 in future optoelectronic devices. The material's thermoelectric response is also evaluated using the BoltzTrap code. The figure of merit (ZT) value is achieved up to 0.83 in the case of MgAl2C2 which indicates that it exhibits strong thermoelectric behavior and it is a promising candidate for applications in renewable energy devices.