Intermolecular coupling enhanced thermopower in single-molecule diketopyrrolopyrrole junctions

Fang Chao; Almughathawi Renad; Wu Qingqing; Cao Wenqiang; Chen Hang; Hou Songjun; Gu Yu; Zhang Hewei; Zhao Yi; Zheng Jueting; Li Guopeng; Shi Jia; Liu Junyang; Mao Bing-Wei; Liu Zitong; Lambert Colin J.; Hong Wenjing

doi:10.1360/nso/20220039

National Science Open (Dec 2022)

Intermolecular coupling enhanced thermopower in single-molecule diketopyrrolopyrrole junctions

Fang Chao,
Almughathawi Renad,
Wu Qingqing,
Cao Wenqiang,
Chen Hang,
Hou Songjun,
Gu Yu,
Zhang Hewei,
Zhao Yi,
Zheng Jueting,
Li Guopeng,
Shi Jia,
Liu Junyang,
Mao Bing-Wei,
Liu Zitong,
Lambert Colin J.,
Hong Wenjing

Affiliations

Fang Chao: ["State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China"]
Almughathawi Renad: ["Department of Physics, Lancaster University, Lancaster LA1 4YB, UK","Department of Physics, Faculty of Science, Taibah University, Madinah, Saudi Arabia"]
Wu Qingqing: ["Department of Physics, Lancaster University, Lancaster LA1 4YB, UK"]
Cao Wenqiang: ["State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China"]
Chen Hang: ["State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China"]
Hou Songjun: ["Department of Physics, Lancaster University, Lancaster LA1 4YB, UK"]
Gu Yu: ["State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China"]
Zhang Hewei: ["State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China"]
Zhao Yi: ["State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China"]
Zheng Jueting: ["State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China"]
Li Guopeng: ["State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China"]
Shi Jia: ["State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China"]
Liu Junyang: ["State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China","Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province (IKKEM), Xiamen 361005, China"]
Mao Bing-Wei: ["State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China"]
Liu Zitong: ["State Key Laboratory of Applied Organic Chemistry (SKLAOC), College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, China","Beijing National Laboratory for Molecular Sciences, Beijing 100190, China"]
Lambert Colin J.: ["Department of Physics, Lancaster University, Lancaster LA1 4YB, UK"]
Hong Wenjing: ["State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China","Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province (IKKEM), Xiamen 361005, China","Beijing National Laboratory for Molecular Sciences, Beijing 100190, China"]

DOI: https://doi.org/10.1360/nso/20220039
Journal volume & issue: Vol. 2

Abstract

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Sorting out organic molecules with high thermopower is essential for understanding molecular thermoelectrics. The intermolecular coupling offers a unique chance to enhance the thermopower by tuning the bandgap structure of molecular devices, but the investigation of intermolecular coupling in bulk materials remains challenging. Herein, we investigated the thermopower of diketopyrrolopyrrole (DPP) cored single-molecule junctions with different coupling strengths by varying the packing density of the self-assembled monolayers (SAM) using a customized scanning tunneling microscope break junction (STM-BJ) technique. We found that the thermopower of DPP molecules could be enhanced up to one order of magnitude with increasing packing density, suggesting that the thermopower increases with larger neighboring intermolecular interactions. The combined density functional theory (DFT) calculations revealed that the closely-packed configuration brings stronger intermolecular coupling and then reduces the highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) gap, leading to an enhanced thermopower. Our findings offer a new strategy for developing organic thermoelectric devices with high thermopower.

Published in National Science Open

ISSN: 2097-1168 (Print); 2097-1400 (Online)
Publisher: Science Press
Country of publisher: China
LCC subjects: Science; Technology: Engineering (General). Civil engineering (General)
Website: https://www.sciengine.com/NSO/home

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