Revealing the Electrophilic‐Attack Doping Mechanism for Efficient and Universal p‐Doping of Organic Semiconductors

Abstract

Doping is of great importance to tailor the electrical properties of semiconductors. However, the present doping methodologies for organic semiconductors (OSCs) are either inefficient or can only apply to some OSCs conditionally, seriously limiting their general applications. Herein, a novel p‐doping mechanism is revealed by investigating the interactions between the dopant trityl tetrakis(pentafluorophenyl) borate (TrTPFB) and poly(3‐hexylthiophene) (P3HT). It is found that electrophilic attack of the trityl cations on thiophenes results in the formation of tritylated thiophenium ions, which subsequently induce electron transfer from neighboring P3HT chains to realize p‐doping. This unique p‐doping mechanism enables TrTPFB to p‐dope various OSCs including those with high ionization energy (IE ≈ 5.8 eV). Moreover, this doping mechanism endows TrTPFB with strong doping capability, leading to doping efficiency of over 80% in P3HT. The discovery and elucidation of this novel doping mechanism not only points out that strong electrophiles are a class of efficient p‐dopants for OSCs, but also provides new opportunities toward highly efficient doping of various OSCs.

Remarkable conductivity enhancement in P-doped polythiophenes via rational engineering of polymer-dopant interactions

“…P3HT exhibited a conductivity of 6.6 (±0.5) Â 10 À5 S cm À1 at 0.2 mol% F4TCNQ concentration, and dramatically reached its maximum conductivity of 1.9 (±0.2) Â 10 À2 S cm À1 at an F4TCNQ concentration of 2.5 mol%. This value is very comparable to the previous reports on the doped P3HT, for instance the one by Kim et al [23] and the other by Hu et al [26], though, it is lower than that of the state-of-the-art doped P3HT due primarily to the lower Mn in the current study. It was shown that increasing the Mn by ca.…”

Accelerated Preparation of Polypeptides and Related Hybrid Materials from a Disintegrable Initiator Array with Masked Carbenium Precursors

“…Such efficiencies were slightly lower than that of F 4 TCNQ (ca. 35% at a 10% doping ratio), which was attributed to the bulkiness of the PBLG arms that could inhibit the electron transfer between P3HT segments or chains , (Figure a, purple arrow). This also explained why the polaron generation efficiency decreased with increased doping ratios: the steric hindrance from the PBLG arms would apparently increase as the grafting density increased.…”

“…As a proof of concept, we went on to assess these polypeptides’ capability of peptidylation and doping of OSCs. Many of these OSCs are known to be doped by Lewis acids, and very recently, we have reported a highly effective doping method by using a carbenium salt, trityl tetra­(pentafluorophenyl)­borate (TrTPFB) . The trityl cation reacts with various semiconductive polymers by performing electrophilic attacks on the aromatic moieties on the polymers, yielding the corresponding Wheland intermediates that subsequently disproportionate to generate polarons − for substantially increased conductivity.…”

“…In terms of final conductivity, the performance of PBLG-BHD + as a dopant was close to that of the widely used dopant, 2,3,5,6-tetrafluoro-tetracyanoquinodimethane (F 4 TCNQ, reaching ca. 10 −2 S•cm −1 using the same method at a 10% doping ratio 52 ). We further employed electron spin resonance (ESR) and UV−vis−NIR spectroscopy to detect the polarons induced by the grafting-onto doping process in the doped film.…”

Thermally Activated Aromatic Ionic Dopants (TA‐AIDs) Enabling Stable Doping, Orthogonal Processing and Direct Patterning

“…The strong electrophilic and electron-deficient nature of tropylium cation acts as a reactive species for doping organic semiconductors. [50] Upon heating, tropylium cations can dissociate from T-PCCp ion pair into a free or weakly ionic bonded cation. This electrophilic cation can attack electron-rich 3,4-ethylenedioxythiophene (EDOT) on the P1 polymer backbone.…”