First-principles calculations to investigate structural, electronic, optical, thermoelectric and NMR properties of K2PtCl6 for optoelectronic and energy conversion applications

• DFT study of K 2 PtCl 6 covering structural and electronic properties. • Accurate structure from FP-LAPW consistent with experiments. • Wide indirect bandgap (3.42 eV) for UV optoelectronic uses. • Strong UV absorption and good transparency in visible region. • Thermoelectric and NMR analyses confirm multifunctional potential. In this work, we present a comprehensive first-principles investigation of potassium hexachloroplatinate (K 2 PtCl 6 ) using density functional theory within the generalized gradient approximation (GGA) and the modified Becke–Johnson (mBJ-GGA) functional. Structural optimization predicts a stable cubic phase for K 2 PtCl 6 , demonstrating the reliability of the adopted computational approach, demonstrating the reliability of the adopted computational approach. Electronic structure calculations reveal that K 2 PtCl 6 is an indirect wide-bandgap semiconductor, making it suitable for ultraviolet optoelectronic applications, particularly in devices requiring transparency in the visible range. Mechanical analysis indicates that the compound is mechanically stable and exhibits ductile behavior, which is advantageous for practical device fabrication. The optical response shows strong absorption in the ultraviolet region combined with high transparency in the visible range, suggesting potential use in UV-protective and optoelectronic devices. Thermoelectric transport calculations predict moderate Seebeck coefficients, with a value of ∼250 µV/K obtained for p-type doping at 300 K, indicating possible applicability in medium-temperature thermoelectric applications. Overall, the present study provides a consistent theoretical description of the structural, electronic, optical, and transport properties of K 2 PtCl 6 and highlights its potential for optoelectronic and energy-related technologies, thereby offering useful guidance for future experimental and applied research