High-performance one-dimensional thermoelectric materials: polyyne chains and their derivatives

Thermoelectricity has emerged as a crucial field in response to pressing environmental concerns and the increasing demand for efficient waste energy conversion. With the miniaturization of devices, there is a demand for smaller material systems with minimal energy dissipation and comparable efficiencies for converting heat into electricity. This study proposes a low-dimensional pure carbon-based system, specifically a one-dimensional (1D) polyyne chain and its derivatives (two, three, and four chains), for thermoelectric applications. We investigated the optimization of the thermoelectric figure of merit (ZT) through doping and strain effects at different temperatures. Thermodynamic and structural stability analyzes, including formation energy analyzes, phonon dispersion studies, and ab initio molecular dynamics simulations reveal that the material maintains its structural integrity under prolonged high temperature conditions, making it a promising candidate for practical applications. For n-type doping, we achieve a maximum ZT of 3.06 for one polyyne chain at 700 K. The corresponding maxima for the two, three and four chains are 1.26, 1.65, and 1.60 respectively. Additionally, we examine cumulative lattice thermal conductivity as a function of phonon frequency and mean free path, along with other phonon properties, such as heat capacity, phonon lifetime, and group velocity, in detail, for different temperatures. The findings underscore the potential of polyyne chain systems in enhancing the efficiency of thermoelectric devices, thus contributing to the advancement of energy harvesting technologies.