Open AccessAn Organic Borate Salt with Superior p ‐Doping Capability for Organic Semiconductors
Author(s) -
Wegner Berthold,
Lungwitz Dominique,
Mansour Ahmed E.,
Tait Claudia E.,
Tanaka Naoki,
Zhai Tianshu,
Duhm Steffen,
Forster Michael,
Behrends Jan,
Shoji Yoshiaki,
Opitz Andreas,
Scherf Ullrich,
ListKratochvil Emil J. W.,
Fukushima Takanori,
Koch Norbert
Publication year - 2020
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.202001322
Subject(s) - boron , doping , organic semiconductor , salt (chemistry) , materials science , semiconductor , nanotechnology , inorganic chemistry , chemistry , optoelectronics , organic chemistry
Abstract Molecular doping allows enhancement and precise control of electrical properties of organic semiconductors, and is thus of central technological relevance for organic (opto‐) electronics. Beyond single‐component molecular electron acceptors and donors, organic salts have recently emerged as a promising class of dopants. However, the pertinent fundamental understanding of doping mechanisms and doping capabilities is limited. Here, the unique capabilities of the salt consisting of a borinium cation (Mes 2 B + ; Mes: mesitylene) and the tetrakis(penta‐fluorophenyl)borate anion [B(C 6 F 5 ) 4 ] − is demonstrated as p‐type dopant for polymer semiconductors. With a range of experimental methods, the doping mechanism is identified to comprise electron transfer from the polymer to Mes 2 B + , and the positive charge on the polymer is stabilized by [B(C 6 F 5 ) 4 ] − . Notably, the former salt cation leaves during processing and is not present in films. The anion [B(C 6 F 5 ) 4 ] − even enables the stabilization of polarons and bipolarons in poly(3‐hexylthiophene), not yet achieved with other molecular dopants. From doping studies with high ionization energy polymer semiconductors, the effective electron affinity of Mes 2 B + [B(C 6 F 5 ) 4 ] − is estimated to be an impressive 5.9 eV. This significantly extends the parameter space for doping of polymer semiconductors.