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 mu V K-1, respectively. The maximum power factors of the p-and n-type SiNWs are obtained as 8.79 and 8.87 mW (m K-2)(-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 x 10(-2) and 6.7 x 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 mu V K-1 and 14.2 mW (m K-2)(-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%.