An Organic Borate Salt with Superior p‐Doping Capability for Organic Semiconductors. Issue 17 (6th July 2020)

• Record Type: Journal Article
• Authors: 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; List‐Kratochvil, Emil J. W.; Fukushima, Takanori; Koch, Norbert
• Is Part Of: Advanced science. Volume 7:Issue 17(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-07-06
• Subjects: bipolarons -- borate salt -- doping -- organic semiconductors -- polarons; Science -- Periodicals; 505
• DOI: 10.1002/advs.202001322
• Languages: English
• ISSNs: 2198-3844

Abstract

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 (Mes2 B + ; Mes: mesitylene) and the tetrakis(penta‐fluorophenyl)borate anion [B(C6 F5 )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 Mes2 B +, and the positive charge on the polymer is stabilized by [B(C6 F5 )4 ] − . Notably, the former salt cation leaves during processing and is not present in films. The anion [B(C6 F5 )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 Mes2 B + [B(C6 F5 )4 ] − is estimated to be an impressive 5.9 eV. This significantly extends the parameter space for doping of polymer semiconductors. Abstract : The salt of the cation (Mes2 B + ; Mes: mesitylene) and the anion [B(C6 F5 )4 ] − is introduced as superior p‐type dopant for organic semiconductors. The doping mechanism involves electron transfer from the semiconductor to Mes2 B +, and the positive charge is stabilized by [B(C6 F5 )4 ] − . For poly(3‐hexylthiophene), the anion even stabilizes bipolarons. The effective electron affinity of Mes2 B + [B(C6 F5 )4 ] − is estimated to be 5.9 eV.