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Polar Side Chains Enhance Processability, Electrical Conductivity, and Thermal Stability of a Molecularly p‐Doped Polythiophene
Author(s) -
Kroon Renee,
Kiefer David,
Stegerer Dominik,
Yu Liyang,
Sommer Michael,
Müller Christian
Publication year - 2017
Publication title -
advanced materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.707
H-Index - 527
eISSN - 1521-4095
pISSN - 0935-9648
DOI - 10.1002/adma.201700930
Subject(s) - dopant , materials science , polythiophene , side chain , thermal stability , polymer , doping , organic semiconductor , chemical engineering , conductive polymer , polymer chemistry , optoelectronics , composite material , engineering
Molecular doping of organic semiconductors is critical for optimizing a range of optoelectronic devices such as field‐effect transistors, solar cells, and thermoelectric generators. However, many dopant:polymer pairs suffer from poor solubility in common organic solvents, which leads to a suboptimal solid‐state nanostructure and hence low electrical conductivity. A further drawback is the poor thermal stability through sublimation of the dopant. The use of oligo ethylene glycol side chains is demonstrated to significantly improve the processability of the conjugated polymer p(g 4 2T‐T)—a polythiophene—in polar aprotic solvents, which facilitates coprocessing of dopant:polymer pairs from the same solution at room temperature. The use of common molecular dopants such as 2,3,5,6‐tetrafluoro‐7,7,8,8‐tetracyanoquinodimethane (F4TCNQ) and 2,3‐dichloro‐5,6‐dicyano‐1,4‐benzoquinone (DDQ) is explored. Doping of p(g 4 2T‐T) with F4TCNQ results in an electrical conductivity of up to 100 S cm −1 . Moreover, the increased compatibility of the polar dopant F4TCNQ with the oligo ethylene glycol functionalized polythiophene results in a high degree of thermal stability at up to 150 °C.