Mechanical, optoelectronic, thermoelectric and photocatalytic analysis of Cs2TlAsX6 (X= Cl, Br, I) lead free double perovskites: Implications for opto-electronic and thermo-electric sense

초록

This work shows a comprehensive analysis of the opto-electronic, thermoelectric, mechanical, and photocatalytic features of the halide double perovskites Cs2TlAsCl6, Cs2TlAsBr6 and Cs2TlAsI6. We used WIEN2k for the computational analyzing. Tran-Blaha modified Becke-Johnson (TB-mBJ) potential was also deployed for the calculation of electronic characteristics. The computed direct band gaps of Cs2TlAsCl6/Br6/I6 are 2.20/1.59/ 1.18 eV with semiconducting nature indicating the promising potential for optoelectronic applications. These materials exhibit broad optical absorption starting from visible region and mostly positioning in the ultraviolet spectrum, making them strong candidates for light-harvesting technologies. Furthermore, dielectric function, refractive index, reflectivity R(omega) and other parameters are demonstrated in detail gives absorption peaks in UV region for Cs2TlAsCl6 and Cs2TlAsBr6, while Cs2TlAsI6 peaks in both visible and UV region. Notably Cs2TlAsI6, the high absorption coefficients alpha(omega) in the ultraviolet region reinforce their suitability for UV-Photodetectors and UV LEDs applications. Transport properties were further explored through an analysis of electrical conductivity, thermal conductivity, and the Seebeck coefficient. Additionally, figure of merit (ZT) was used to evaluate the thermoelectric performance throughout a temperature range (200-800) K. ZT values for Cs2TlAsCl6 are 0.550, Cs2TlAsBr6 0.750 and Cs2TlAsI6 is 0.757 revealing stable behavior and competitive efficiency when compared to conventional materials. Our findings highlight multifunctional nature and application potential of Cs2TlAsX6 (X = Cl, Br, I) perovskites in future optoelectronic, energy conversion devices and solar-driven water-splitting technologies.

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