Sn doping induced n-type to p-type transition in Bi$lt;sub$gt;2$lt;/sub$gt;Se$lt;sub$gt;3$lt;/sub$gt; nanosheets for flexible temperature sensing

Flexible temperature sensors capable of simultaneously delivering high sensitivity, precision, and stability are essential to meet the increasing demands for monitoring temperature changes associated with infections and diseases. Herein, we fabricated a flexible temperature sensor using Bi₂Se₃-based thermosensitive materials. Through Sn-doping, an n-type to p-type transition was realized in Bi₂Se₃ nanosheets, leading to enhanced temperature sensing performance. The Bi_1.97Sn_0.03Se₃ nanosheets with optimal doping level exhibited a high sensitivity of –0.63%/°C. The fabricated temperature sensor could detect skin temperature with high precision and stability. Moreover, by taking advantage of the n–p transition, a flexible double-chain thermoelectric generator consisting of n-type Bi₂Se₃ and p-type Bi_1.97Sn_0.03Se₃ was also fabricated, demonstrating its potential for thermal energy harvesting and self-powered temperature sensing.