聚合物薄膜中同质结诱导的热电势增强
Homojunction-induced thermopower enhancement in polymer films
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中文总结 AI 辅助
该研究通过构建不同掺杂水平的同质结面内分段结构，在不显著降低电导率的前提下大幅增强有机热电器件的热电势，获得高功率因子与创纪录室温ZT值，为导电聚合物热电特性调控提供突破性方法。
中文摘要 AI 辅助
导电聚合物作为新兴热电材料受到关注已逾二十年，但其电导率（σ）与热电势（S）之间的权衡关系是阻碍其实际器件应用的主要挑战。本文报道：通过构建两侧具有不同掺杂水平的同质结组成的面内分段结构，有机热电器件的p型和n型支腿的热电势可在电导率无显著劣化的情况下大幅增强。在这类分段层中，施加正向温度梯度（加热重掺杂 counterpart）时，热电S异常高于组成部分的平均值；施加反向温度梯度时则低于平均值。典型案例为p型PDPP-Se的两级分段薄膜，其获得了210 μV K⁻¹的异常高S和2.5×10⁴ S m⁻¹的σ，进而得到1100 μW m⁻¹ K⁻²的高功率因子（PF）和室温下创纪录的1.36的ZT值。增强的热电势归因于加热时同质结处产生的额外电压，这一点已通过动力学蒙特卡洛模拟得到解释。该发现为调控导电聚合物的热电输运特性提供了突破性方法。
英文摘要
It has been more than twenty years since conductive polymers began to receive attention as an emerging thermoelectric material. However, the trade-off between electrical conductivity (σ) and thermopower (S) has proven to be a major challenge that has obstructed their use in actual devices. Here we report the discovery that the thermopower of the p- and n-type legs of organic thermogenerators can be substantially enhanced, without significant deterioration of σ, by constructing an in-plane segmented structure consisting of a homojunction with different doping levels on either side. In such segmented layers, the S is abnormally higher than the average value of the constituent parts when applying a forward temperature gradient (heating the heavily doped counterpart), while it is lower upon a reverse temperature gradient. Typically, for a two-stage segmented film of p-type PDPP-Se, an abnormally large S of 210 uV K-1 and σ of 2.5*10^4 S m-1 are obtained, resulting in a large power factor (PF) of 1100 uW m-1 K-2 and a record ZT of 1.36 at room temperature. The enhanced thermopower is attributed to an additional voltage developed at the homojunction under heating as explained by kinetic Monte Carlo simulations. This finding provides a breakthrough approach to the modulation of thermoelectric transport properties of conductive polymers.
