Complementary n-Type and p-Type Graphene Films for High Power Factor Thermoelectric Generators

Abstract

Solution-phase exfoliated graphene has always been an attractive material for flexible thermoelectric applications, but traditional oxidative routes suffer from poor flake quality and a lack of quality doping techniques to make complementary n-type and p-type films. Here, it is demonstrated that by changing the adsorbed surfactant during the intercalation-exfoliation process (polyvinylpyrrolidone for n-type, pyrenebutyric acid for p-type), both extremely high electrical conductivity (3010 and 2330 S cm(-1)) and high Seebeck coefficients (53.1 and -45.5 mu V K-1) can be achieved. The result is that both of these films show remarkable power factors, over 600 mu W m(-1) K-2 at room temperature, which is over an order of magnitude better than that in previous works demonstrating complementary n-type and p-type graphene thermoelectric films. Based on these films, a full all-graphene thermoelectric device is constructed as a proof of concept, where a peak power of 5.0 nW is recorded at a temperature difference of 50 K.