Flexible Thermoelectric Generator from Bulk Graphite and Bismuth Traces on Emery Paper

Abstract

Flexible thermoelectrics (TEs) involving simplified processeability are attractive, with limited choice of materials and low endurance, remaining as major challenges. Herein, an economic emery paper‐based thermoelectric generator (PTEG) from graphite as p‐type leg and bismuth as n‐type leg is introduced, prepared by simple bulk tracing. Tracing provides a feasible approach to modulate the TE properties, as supported by finite‐element analysis. From individual bismuth trace a power factor of 5.85 μW m−1 K−2≈100 °C (2.09 μWm−1 K−2at room temperature (RT)) and for graphite a power factor 7.7 μW m−1 K−2at ≈100 °C (≈5.1 μW m−1 K−2at RT) is obtained. A six‐pair p–n module‐integrated PTEG drives an open‐circuit voltage of 35.8 mV producing an output power of 14.6 nW whereas from a 60‐pair PTEG, voltage ≈348 mV with ≈137.5 nW output power is produced for ΔT ≈ 70 K. The scalability of the fabricated PTEGs is understood from Seebeck voltage being directly proportional to the number of p–n modules and is further tested for harvesting waste heat from electronics. This facile approach may be extended to other organic and inorganic TE materials, contributing to the research in self‐powered heat sensors, wearables, and as thermal harvesters in IoT equipment.