Enhanced Thermopower of Graphene Films with Oxygen Plasma Treatment

Abstract

In this work, we show that the maximum thermopower of few layers graphene (FLG) films could be greatly enhanced up to ∼700 μV/K after oxygen plasma treatment. The electrical conductivities of these plasma treated FLG films remain high, for example, ∼10(4) S/m, which results in power factors as high as ∼4.5 × 10(-3) W K(-2) m(-1). In comparison, the pristine FLG films show a maximum thermopower of ∼80 μV/K with an electrical conductivity of ∼5 × 10(4) S/m. The proposed mechanism is due to generation of local disordered carbon that opens the band gap. Measured thermopowers of single-layer graphene (SLG) films and reduced graphene oxide (rGO) films were in the range of -40 to 50 and -10 to 20 μV/K, respectively. However, such oxygen plasma treatment is not suitable for SLG and rGO films. The SLG films were easily destroyed during the treatment while the electrical conductivity of rGO films is too low.

Plasma engineering of graphene

“…108 With the introduction of defects in graphene, values of S and ZT can be increased further. 109 Xiao et al 110 reported maximum thermopower of 700 μV/K at 575 K with oxygen plasma treatment on few layer graphene. Though the electrical conductivity of the sample was determined to decrease from 5 × 10 4 S/m to 10 4 S/m, the increased thermopower resulted in a significant increase of power factor.…”

Arsenene and Antimonene: Two-Dimensional Materials with High Thermoelectric Figures of Merit

“…Graphene (monolayer [38,39] and bilayer [40]) exfoliated on a SiO 2 =Si substrate, for example, provides a significant thermoelectric response and the usual temperature dependence of S can be overcome on a SiC substrate [41]. Performance improvements have been achieved through O plasma treatment [42] and molecular decoration [43]. Interestingly, high-density defects can also have positive effects [44].…”

Cross-plane enhanced thermoelectricity and phonon suppression in graphene/MoS 2 van der Waals heterostructures

“…From the viewpoint of thermoelectricity, the in-plane thermal conductance of graphene [31] is higher than pristine MoS 2 , which makes graphene useful for thermal management [32], but reduces its efficiency as a thermoelectric material. Since pristine monolayer MoS 2 has a lower thermal conductance, our aim below is to examine whether this material can form a basis for the design of high-efficiency thermoelectric materials.…”