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

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 (σ). Conventional surface charge-transfer doping can be a solution to enhance σ 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, σ is improved while maintaining high S. This approach achieves a record-high PF of 1698 μW/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.