Open AccessRaising Dielectric Permittivity Mitigates Dopant‐Induced Disorder in Conjugated Polymers
Author(s) -
Upadhyaya Meenakshi,
LuDíaz Michael,
Samanta Subhayan,
Abdullah Muhammad,
Dusoe Keith,
Kittilstved Kevin R.,
Venkataraman Dhandapani,
Akšamija Zlatan
Publication year - 2021
Publication title -
advanced science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.388
H-Index - 100
ISSN - 2198-3844
DOI - 10.1002/advs.202101087
Subject(s) - dopant , materials science , seebeck coefficient , doping , dielectric , condensed matter physics , charge carrier , thermoelectric effect , barium titanate , permittivity , conductivity , optoelectronics , thermal conductivity , composite material , chemistry , physics , thermodynamics
Conjugated polymers need to be doped to increase charge carrier density and reach the electrical conductivity necessary for electronic and energy applications. While doping increases carrier density, Coulomb interactions between the dopant molecules and the localized carriers are poorly screened, causing broadening and a heavy tail in the electronic density‐of‐states (DOS). The authors examine the effects of dopant‐induced disorder on two complimentary charge transport properties of semiconducting polymers, the Seebeck coefficient and electrical conductivity, and demonstrate a way to mitigate them. Their simulations, based on a modified Gaussian disorder model with Miller‐Abrahams hopping rates, show that dopant‐induced broadening of the DOS negatively impacts the Seebeck coefficient versus electrical conductivity trade‐off curve. Increasing the dielectric permittivity of the polymer mitigates dopant‐carrier Coulomb interactions and improves charge transport, evidenced by simultaneous increases in conductivity and the Seebeck coefficient. They verified this increase experimentally in iodine‐doped P3HT and P3HT blended with barium titanate (BaTiO 3 ) nanoparticles. The addition of 2% w/w BaTiO 3 nanoparticles increased conductivity and Seebeck across a broad range of doping, resulting in a fourfold increase in power factor. Thus, these results show a promising path forward to reduce the dopant‐charge carrier Coulomb interactions and mitigate their adverse impact on charge transport.