抗坏血酸后处理化学气相法制备的聚3,4-乙撑二氧噻吩薄膜及其热电性能

Effects of ascorbic acid post-treatment on thermoelectric properties of poly(3,4-ethylenedioxythiophene)thin films by a vapor phase polymerization

为了获得高热电性能薄膜材料,采用抗坏血酸(VC)作为还原剂对PEDOT-Tos-PPP薄膜进行后处理,研究了不同浓度的VC水溶液对薄膜热电性能的影响,并研究了后处理薄膜在空气中的稳定性.结果表明,经浓度为20%的VC水溶液处理后,薄膜功率因子呈现最大值55.6μW·m^-1·K^-2,是处理之前(32.6μW·m^-1·K^-2)的1.7倍,室温下最大的ZT值为0.032.经过VC处理后PEDOT薄膜的电导率和Seebeck系数在空气中表现出不稳定的特性,主要是由于空气中的氧气导致薄膜表面中性态PEDOT进一步发生氧化引起的.

Thermoelectric(TE)material is a kind of energy conversion material,which can be used for power generation and refrigeration.Until now,traditional inorganic TE materials have shown high dimensionless thermoelectric figure of merit(ZT)values.But their expensive raw material and high processing cost,heavy metal pollution and poor processability limit their broad applications.Poly(3,4-ethylenedioxythiophene)(PEDOT)conducting polymers possess some excellent features,such as high electrical conductivity,low thermal conductivity,flexibility,low cost,abundance,and light weight.More and more attention has recently been paid to the TE properties of PEDOT polymers and PEDOT polymer based nanocomposites.Ascorbic acid(VC)is used as a reducing agent to tune the PEDOT-Tos-PPP film.The PEDOT-Tos-PPP films via VPP technique are treated with VC solutions with different concentrations.The TE properties of the films before and after being treated with VC at different concentrations are measured.The effect of concentration of VC aqueous solution on the thermoelectric properties and stabilities of the film are studied.The results indicate that the power factor of the film after being treated with 20%VC is 55.6μW·m^–1·K^–2,which is 1.7 times as high as that of the pristine PEDOT-Tos-PPP film(34.4μW·m^–1·K^–2).The maximum ZT value at room temperature is 0.032.After the VC treatment,the conductivity and Seebeck coefficient of the PEDOT film show unstable characteristics in the air,which is mainly due to the further oxidation of the neutral state on the PEDOT film surface in the air.