K2AgInCl6: A promising material for optoelectronic and thermoelectric applications

Using the FP-LAPW method with the exchange and correlation potentials of the GGA and mBJ-GGA approximations, we have studied the structural, electronic, thermoelectric, and optical properties of the double perovskite halide compound K2AgInCl6. Our results indicate that this compound is stable in the nonmagnetic phase and exhibits structural stability according to the normative values ​​of the Goldsmith factor (t) and octahedral factor (μ). It is thermodynamically stable, as evidenced by negative formation energy. K2AgInCl6 acts as a semiconductor, displaying a direct band gap of 1.162 eV in GGA and 2.944 eV in mBJ-GGA. Thermoelectric analysis reveals excellent properties, with ZT values ​​close to unity, but nevertheless, the GGA approximation performs well at medium and high temperatures (300-800 K), while mBJ-GGA is more efficient at lower temperatures (50-100 K), with ZTs ranging from 0.73 to 0.7 for the latter approximation. In addition, K2AgInCl6 shows transparency in the infrared and visible spectrums, as well as strong absorption and reflectivity in the UV spectrum, making it suitable for various applications, including in broadband solar cells to improve efficiency through extended absorption. In optoelectronics, it can serve as a UV light emitter in high-power LEDs and potentially as a UV filter to protect materials and people from harmful radiation.