High Seebeck Coefficient in Mixtures of Conjugated Polymers |
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| Authors: | Guangzheng Zuo Xianjie Liu Mats Fahlman Martijn Kemerink |
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| Affiliation: | 1. Complex Materials and Devices, Department of Physics, Chemistry and Biology, Link?ping University, Link?ping, Sweden;2. Division of Surface Physics and Chemistry, Department of Physics, Chemistry and Biology, Link?ping University, Link?ping, Sweden |
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| Abstract: | A universal method to obtain record‐high electronic Seebeck coefficients is demonstrated while preserving reasonable conductivities in doped blends of organic semiconductors through rational design of the density of states (DOSs). A polymer semiconductor with a shallow highest occupied molecular orbital (HOMO) level‐poly(3‐hexylthiophene) (P3HT) is mixed with materials with a deeper HOMO (PTB7, TQ1) to form binary blends of the type P3HTx:B1‐x (0 ≤ x ≤ 1) that is p‐type doped by F4TCNQ. For B = PTB7, a Seebeck coefficient S = 1100 µV K?1 with conductivity σ = 0.3 S m?1 at x = 0.10 is achieved, while for B = TQ1, S = 2000 µV K?1 and σ = 0.03 S m?1 at x = 0.05 is found. Kinetic Monte Carlo simulations with parameters based on experiments show good agreement with the experimental results, confirming the intended mechanism. The simulations are used to derive a design rule for parameter tuning. These results can become relevant for low‐power, low‐cost applications like (providing power to) autonomous sensors, in which a high Seebeck coefficient translates directly to a proportionally reduced number of legs in the thermogenerator, and hence in reduced fabrication cost and complexity. |
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| Keywords: | conjugated polymers doping kinetic Monte Carlo simulations organic thermoelectrics Seebeck coefficients |
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