Flexible Thermoelectric Generators Composed of n‐and p‐Type Silicon Nanowires Fabricated by Top‐Down Method

Abstract

This study demonstrates the fabrication and characterization of a flexible thermoelectric (TE) power generator composed of silicon nanowires (SiNWs) fabricated by top‐down method and discusses its strain‐dependence analysis. The Seebeck coefficients of the p‐ and n‐type SiNWs used to form a pn‐module are 156.4 and −146.1 µV K−1, respectively. The maximum power factors of the p‐ and n‐type SiNWs are obtained as 8.79 and 8.87 mW (m K2)−1, respectively, under a convex bending of 1.11%, respectively; these are the largest values among the power factors hitherto reported for SiNWs. The dimensionless figure of merit (ZT) values of the SiNWs at room temperature are 6.8 × 10−2 and 6.7 × 10−2 for the convex bent p‐ and n‐type SiNWs, respectively, with a strain of 1.11%. The thermoelectric properties of the pn‐module and its component SiNWs are characterized under strain conditions ranging from −1.11% to 1.11%. The maximum Seebeck coefficient and power factor of the pn‐module are obtained as 448 µV K−1 and 14.2 mW (m K2)−1, respectively, under convex bending of 1.11%. Moreover, the mechanical stability of the TE characteristics of the pn‐module is demonstrated through a continuous bending test of 3000 cycles under convex bending of 0.66%.