Fe 도핑을 통한 CuI 열전소재의 열전도도 저감

Abstract

Thermoelectrics is an energy conversion technology that can convert heat energy directly into electrical energy or vice versa. This technology is commonly evaluated by a figure-of-merit, zT = S2σT/κ, where S is the Seebeck coefficient, σ is the electrical conductivity, T is the absolute temperature, and κ is the thermal conductivity [1]. Currently, commercially available thermoelectric materials rely on bismuth (Bi), tellurium (Te), and lead (Pb). These materials have a performance of zT ~ 1, corresponding to an energy conversion efficiency of approximately 10% of the Carnot cycle [2]. However, these materials are limited by toxic and expensive elements. One promising candidate material is CuI with zT ~ 0.2, which contains relatively abundant and inexpensive elements such as copper (Cu) and iodine (I) [3]. The reduction of thermal conductivity is a crucial factor for improving the thermoelectric figure-of-merit. The thermal conductivity is affected by grain boundaries which strongly depend on the starting particle size [4]. Figure 1 shows the decrease in nanoparticle size with increasing Fe doping concentration in the CuI system. Here, we present an investigation of the thermoelectric properties of CuI system with the Fe doping concentration. Based on the results, the effect of the Fe doping on the nanostructure that affect the thermal transport properties will be discussed.