Study of elastic, structural, thermoelectric and optoelectronics characteristics of Na <sub>2</sub> YCuX <sub>6</sub> (X = Br, Cl) halide double perovskites
Nasarullah, Muhammad Zakyas Choudary, Shatha A. Aldaghfag, Misbah Misbah, Muhammad Yaseen, Mubashar Nazar, R. Neffati
Abstract
Abstract The structural, electronic, optical, elastic, and thermoelectric (TE) characteristics of Na 2 YCuX 6 (X = Br, Cl) halide double-perovskites (HDPs) were investigated by using first principle approach within WIEN2K code. Perdew, Burke and Ernzerhof generalized-gradient approximation (PBEsol-GGA) with modified Becke-Johnson (mBJ) potential were used in the current investigations. Enthalpy of formation energies (E f ) determined for Na 2 YCuBr 6 and Na 2 YCuCl 6 were −2.29 and −1.955 eV, correspondingly which verify the stability of both compounds. Na 2 YCuBr 6 is discovered to be semiconducting with indirect bandgap (E g ) of 2.492 and Na 2 YCuCl 6 has direct E g of 2.571 eV. Absorption coefficient shows largest values at 5.74 and 6.92 eV for Na 2 YCuBr 6 and Na 2 YCuCl 6 , correspondingly, which lie in UV range. Pugh’s ratio (B/G) values were calculated as 2.00 and 4.62 for Na 2 YCuCl 6 and Na 2 YCuBr 6 , correspondingly which ensure the ionic bond and ductile characteristics of the compounds. From the TE calculations, ZT shows maximum values of 0.74 and 0.73 for Na 2 YCuBr 6 and Na 2 YCuCl 6 , respectively. Results showed that investigated materials are efficient candidates for optoelectronic and TE appliances.