Achieving Boosted Thermoelectric Power Factor of MoS2 through Selective Charged-Impurity-Free Doping

Abstract

Ultrathin two-dimensional (2D) transition metal dichalcogenides (TMDs) exhibit unique band structures, allowing promising thermoelectric properties. Achieving a high power factor (PF) for thermoelectric generators (TEGs) requires optimizing both the Seebeck coefficient (S) and electrical conductivity (sigma). Conventional surface charge-transfer doping can be a solution to enhance sigma by introducing additional electrons. However, residual organic dopants act as charged impurities, degrading charge transport and lowering PF due to the intensified trade-off between carrier concentration and S. We propose a charged-impurity-free diffusion doping method for CVD-grown molybdenum disulfide (MoS2) to enhance PF. By depositing organic dopants on the contact region and enabling electron diffusion into the channel via carrier concentration gradients, sigma is improved while maintaining high S. This approach achieves a record-high PF of 1698 mu W/mK2 for CVD-grown TMDs. Our strategy offers a promising pathway to enhance thermoelectric performance, not limited by the exacerbated trade-off relationship observed in conventional doping methods.