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Understanding the Effects of Molecular Dopant on n‐Type Organic Thermoelectric Properties
Author(s) -
Un HioIeng,
Gregory Shawn A.,
Mohapatra Swagat K.,
Xiong Miao,
Longhi Elena,
Lu Yang,
Rigin Sergei,
Jhulki Samik,
Yang ChiYuan,
Timofeeva Tatiana V.,
Wang JieYu,
Yee Shan K.,
Barlow Stephen,
Marder Seth R.,
Pei Jian
Publication year - 2019
Publication title -
advanced energy materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.08
H-Index - 220
eISSN - 1614-6840
pISSN - 1614-6832
DOI - 10.1002/aenm.201900817
Subject(s) - dopant , materials science , thermoelectric effect , seebeck coefficient , thermoelectric materials , doping , counterion , organic semiconductor , electrical resistivity and conductivity , semiconductor , chemical physics , chemical engineering , nanotechnology , optoelectronics , organic chemistry , ion , composite material , thermal conductivity , chemistry , thermodynamics , physics , engineering , electrical engineering
Abstract Molecular doping is a powerful method to fine‐tune the thermoelectric properties of organic semiconductors, in particular to impart the requisite electrical conductivity. The incorporation of molecular dopants can, however, perturb the microstructure of semicrystalline organic semiconductors, which complicates the development of a detailed understanding of structure–property relationships. To better understand how the doping pathway and the resulting dopant counterion influence the thermoelectric performance and transport properties, a new dimer dopant, (N‐DMBI) 2 , is developed. Subsequently, FBDPPV is then n‐doped with dimer dopants (N‐DMBI) 2 , (RuCp*mes) 2 , and the hydride‐donor dopant N‐DMBI‐H. By comparing the UV–vis–NIR absorption spectra and morphological characteristics of the doped polymers, it is found that not only the doping mechanism, but also the shape of the counterion strongly influence the thermoelectric properties and transport characteristics. (N‐DMBI) 2 , which is a direct electron‐donating dopant with a comparatively small, relatively planar counterion, gives the best power factor among the three systems studied here. Additionally, temperature‐dependent conductivity and Seebeck coefficient measurements differ between the three dopants with (N‐DMBI) 2 yielding the best thermoelectric properties. The results of this study of dopant effects on thermoelectric properties provide insight into guidelines for future organic thermoelectrics.