The ability of n-type polymer thermoelectric materials to tolerate high doping loading limits further development of n-type polymer conductivity. Herein, we report two alcohol-soluble n-type polythiophene derivatives that are n-PT3 and n-PT4. Due to the ability of two polymers to tolerate doping loading more significantly than 100 mol%, both achieve electrical conductivity > 100 S cm -1 . Moreover, the conductivity of both polythiophenes remains almost constant at high doping concentrations with excellent doping tunability, which may be related to their ability to overcome charging-induced backbone torsion and morphology change caused by saturated doping. The characterizations revealed that n-PT4 has a high doping level and carrier concentration (> 3.10×10 20 cm -3 ), and the carrier concentration continues to increase as the doping concentration increases. In addition, doping leads to improved crystal structure of n-PT4, and the crystallinity does not decrease significantly with increasing doping concentration; even the carrier mobility increases with it. The synergistic effect of these two leads to both n-PT3 and n-PT4 achieving a breakthrough of 100 in conductivity and power factor. The DMlmC-doped n-PT4 achieves a power factor of over 150 μW m -1 K -2 . These values are among the highest for n-type organic thermoelectric materials. This article is protected by copyright. All rights reserved.