Extending the p-Doping of Polymers to an Air Stable Lewis Acid–Base Adduct by Increasing the Acidity of the Dopant

Abstract

Among various molecular p-dopants, some Lewis acids have shown recognizable doping effect by the formation of Lewis acid–base adduct for increased hole concentration in organic semiconductors. However, the doping product is often unstable in air by the interference of water. Here near amorphous conjugated polymer poly­(indacenodithiophene-co-benzothiadiazole) (IDT-BT) was doped with four Lewis acid dopants of varying acidities, zinc-, borane-, carbonium- and oxonium-based molecules, respectively. Bearing stronger acidity, the oxonium dopant (C6H15O)+BF4 – yielded the most air-stable Lewis acid–base adduct, which was confirmed by direct comparison of electron paramagnetic resonance and UV–vis absorption spectra of the four doping systems measured in air. A single polaron species of radical cation was produced between the IDT-BT host and the oxonium dopant, with a binding stoichiometry of 1:1 according to the model study using a benzothiadiazole-derivatized molecule. Via modulating the dopant quantity, the performance of thin-film transistors based on (C6H15O)+BF4 –-doped IDT-BT was optimized with enhanced mobility, significantly reduced threshold voltage, higher on/off ratio, and excellent air-stability due to the additional carriers produced by the stable Lewis acid–base adduct. Notably, while the semiconductor layer was processed in air, the (C6H15O)+BF4 –-doped device exhibited almost no loss of performance as compared with that under inert atmosphere. We demonstrate that the performance and air stability of Lewis acid-doped polymer and transistor devices thereby can be improved by increasing the acidity of the dopant.

Improving Carrier Mobility of Near-Amorphous Donor–Acceptor Conjugated Polymer Thin Films via Promoting Intensive and Continuous Polymer Aggregations

“…We observe that the maximum mobilities of the different samples (Table S1) exhibit a similar trend (i.e., the carrier mobility increases with chlorohexadecane content), and the maximum mobility of 1% chlorohexadecane-treated IDTBT films is 3.72 cm 2 V –1 s –1 after annealing. The mobility of the OFET device prepared by the transfer method is the highest so far. ,, It is roughly 2-fold increase in maximum carrier mobility compared to the CB film after annealing. Table S2 shows the mobility of IDTBT films in the previous literature.…”

“…The mobility of the OFET device prepared by the transfer method is the highest so far. 4,27,49 It is roughly 2-fold increase in maximum carrier mobility compared to the CB film after annealing. Table S2 shows the mobility of IDTBT films in the previous literature.…”

“…Consequently, additional mobile carriers are obtained by doping, which facilitates the acquisition of high carrier mobilities. The doping of (C 6 H 15 O) + BF 4 – increases the mobility from 1.13 to 1.40 cm 2 V –1 s –1 without changing the film morphology . Sirringhaus et al removed water in the film from the void by inserting molecular additives to increase carrier mobility, stability, and homogeneity .…”

“…13 It is shown that the average carrier mobility (μ ave ) is 2.0 ± 0.2 cm 2 V −1 s −1 and the maximum carrier mobility (μ max ) is 3.6 cm 2 V −1 s −1 − increases the mobility from 1.13 to 1.40 cm 2 V −1 s −1 without changing the film morphology. 27 Sirringhaus et al removed water in the film from the void by inserting molecular additives to increase carrier mobility, stability, and homogeneity. 28 They have also used an antisolvent processing method, which significantly improved the device performance and environmental stability of IDTBT films, and found that the enhanced crystallinity of the film in the effect of antisolvent hindered electron trapping and eliminated charge traps, allowing the mobility of ∼2 cm 2 V −1 s −1 .…”

Air/Liquid Interfacial Self-Assembled Intrinsically Stretchable IDT-BT Film Combining a Deliberate Transfer Adherence Strategy for Stretchable Electronics

“…Currently, only a few literature have reported IDT-BT transistors with the limited dielectrics including CYTOP, – poly­(tetrafluoroethylene), air, and deionized water, where most of the IDT-BT films were prepared by a spin-coating method, and most of dielectrics are not elastic which is not compatible with the stretchable electronics. For example, McCulloch’s group has applied the CYTOP dielectric to prepare the IDT-BT transistor on a rigid glass substrate.…”