Here we show that molecular doping of polymer thermoelectrics increases the electrical conductivity while reducing the thermal conductivity. A high-throughput methodology based on annealing and doping gradients within individual films is employed to self-consistently analyze and correlate electrical and thermal characteristics for the equivalent of >100 samples. We focus on the benchmark material system poly(2,5-bis(3-alkylthiophen-2-yl)thieno[3,2-b]thiophene) (PBTTT) doped with molecular acceptor 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ). The thermal conductivity of neat PBTTT films is dominated by the degree of crystallinity, with thermal percolation observed for annealing temperatures >170 °C. Upon doping the samples with a relatively low amount of F4TCNQ (anion content <1 mol %), the thermal conductivity exhibits a two-fold reduction without compromising the crystalline quality, which resembles the effect of alloy scattering observed in several inorganic systems. The analysis of the relation between thermal and electrical conductivities shows that thermal transport is dominated by a doping-induced reduced lattice contribution.

中文翻译：

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通过分子掺杂降低聚合物半导体的晶格热导率。

在这里，我们表明聚合物热电分子掺杂提高了电导率，同时降低了热导率。采用基于单个膜内退火和掺杂梯度的高通量方法，可以自洽地分析和关联> 100个样本的电和热特性。我们专注于基准材料系统聚（2,5-双（3-烷基噻吩-2-基）噻吩并[3,2- b（噻吩）（PBTTT）掺杂有分子受体2,3,5,6-四氟-7,7,8,8-四氰基喹二甲烷（F4TCNQ）。纯PBTTT薄膜的热导率主要由结晶度决定，在退火温度> 170°C时观察到热渗流。在用相对较少量的F4TCNQ（阴离子含量<1 mol％）掺杂样品后，热导率会表现出两倍的降低，而不会损害晶体质量，这类似于在几种无机系统中观察到的合金散射效应。对热导率和电导率之间关系的分析表明，热传输受掺杂引起的晶格贡献减少所支配。