Precise control of carrier density is essential to synthesize high-performance thermoelectric materials. Doping by impurities is often frustrated in n-type Bi2Te3 alloys by incomplete activation, bipolar doping, the formation of secondary phases, and prevailing intrinsic point defects such as vacancies. This weakens the reproducibility of synthesis processes and reduces the long-term reliability of material’s performance, hence aging. Here, we explore an impurity-free doping technique to synthesize n-type bismuth tellurium selenides using a cold deformation. The cold deformation determines the electron density via the formation of intrinsic point defects. We confirm that our process is very reproducible, and the properties of the samples are stable without aging even after thermal stresses. Our work provides a promising approach to synthesizing n-type thermoelectric materials in the reproducible and adaptable way.