Thermoelectric Performances Of PbSe Quantum Dotscoated With Reduced Graphene Oxide/PEDOT:PSS Composites

Graphene,which was known as outstanding electrical properties and mechanical properties,had a potential application prospects in the field of thermoelectrics.Recently,PbSe was becoming a promising thermoelectric material due to its high Seebeck coefficient and narrow band gap as well as high carrier mobility.Among all common conductive polymers,PEDOT:PSS has been most investigated and developed to construct organic thermoelectric devices in the field of polymer thermoelectric materials because of its high conductivity and good processing performance.In order to enhance the thermoelectric performance of PEDOT:PSS matrix,the following work was carried out:?1?Utilizing the unique two-dimensional structure of graphene as template,PbSeQDs@RGO was prepared by loading PbSeQDs onto RGO nanosheets with a hydrothermal method.The size and morphology of the quantum dots were controlled by adjusting the content of Pb²⁺in the system.In this experiment,the influence of PbSeQDs to the thermoelectric performance of the hybrid materials was studied.The obtained hybrid material had a two-dimensional structure and could be dispersed in water well and the average size of PbSeQDs was 10-30 nm.The experiment results showed the optimal ZT of PbSeQDs@RGO was 6.13×10^-5 at room temperature.?2?The hybrid material PbSeQDs@RGO was added as a thermoelectric filler to the PEDOT:PSS matrix to prepare PbSeQDs@RGO/PEDOT:PSS composite films.The RGO/PEDOT:PSS films were prepared under the same experimental conditions as the control system.In the control group,the influence of PbSeQDs modified RGO to the thermoelectric performance of PEDOT:PSS was studied.The doping effect of DMSO and EG in the matrix caused a large number of holes in the composite films,and the scattering of holes inhibited the increase of the thermal conductivity of the composite films.At the same time,Seebeck coefficient was improved by the“energy filtering"effect of low energy carriers,due to the two effects of pore boundary and interface in composite.By optimizing the content of PbSeQDs@RGO in PEDOT:PSS matrix?70wt.%?,the composite films with the best thermoelectric performance at the 70 wt.%loading with the ZT of 1.79×10^-3 at 400 K.?3?With PVA as assistant,the different content of PbSeQDs@RGO was mixed with PEDOT:PSS to conduct electrostatic spinning.The experimental results showed that when the content of PbSeQDs@RGO was 0.5 wt.%,the fibers contain smooth surface and even thickness,the average diameter was 500-600 nm.When the content up to 1.0wt.%,the Seebeck coefficient of fibers(160?V·K^-1)was 5 times more than composite films(25?V·K^-1)at room temperature.When the content of PbSeQDs@RGO increased to 1.5 wt.%,the fibers with the maximal electric conductivity of 50 S·m^-1 at room temperature.Unfortunately,attribute to the terrible electric conductivity of PVA,the Power factor of fibers was not much better than composite films.