Molecularly Hybridized Conduction in DPP‐Based Donor–Acceptor Copolymers toward High‐Performance Iono‐Electronics

Abstract

Iono‐electronics, that is, transducing devices able to translate ionic injection into electrical output, continue to demand a variety of mixed ionic–electronic conductors (MIECs). Though polar sidechains are widely used in designing novel polymer MIECs, it remains unclear to chemists how much balance is needed between the two antagonistic modes of transport (ion permeability and electronic charge transport) to yield high‐performance materials. Here, the impact of molecularly hybridizing ion permeability and charge mobility in semiconducting polymers on their performance in electrochemical and synaptic transistors is investigated. A series of diketopyrrolopyrrole (DPP)‐based copolymers are employed to demonstrate the multifunctionality attained by controlling the density of polar sidechains along the backbone. Notably, efficient electrochemical signal transduction and reliable synaptic plasticity are demonstrated via controlled ion insertion and retention. The newly designed DPP‐based copolymers further demonstrate unprecedented thermal tolerance among organic mixed ionic–electronic conductors, a key property in the manufacturing of organic electronics.

Unraveling Polymer–Ion Interactions in Electrochromic Polymers for their Implementation in Organic Electrochemical Synaptic Devices

“…The dynamic range, switching linearity, and cycling endurance demonstrated using ECP-50 are to par with commonly studied organic mixed conductors, as well as other emerging ECRAM materials (e.g., carbon nanotubes and MXenes). [73,77] We envision the current computation-guided discussion on polymer-ion interactions to complement emerging chemistry-guided investigations, [13,33,76] toward high performing organic electrochemical memory materials and devices.…”

Polymer-Based Thermally Stable Chemiresistive Sensor for Real-Time Monitoring of NO2 Gas Emission

“…This was more indirect evidence that the active material in our sensor allows effective diffusion of NO 2 molecules into the bulk as illustrated in Figure d, a property that is enabled herein by both the presence of polar pendant groups as well as amorphous domains within the film bulk. We could thus deduce that, with the presence of TEG side chains, NO 2 gas is attracted toward the polymer backbone and easily abducts the electron from the latter, thus generating mobile holes which translate into a greater electrical conductivity in the device channel. − It is thus implied that semicrystalline films are preferred here (given that the electronic performance is retained, which is the case for DPP-30gT) as the amorphous regions within the active sensing area will facilitate the diffusion of gas molecules into the film bulk (Figure d). , …”

“…30 Our previous works have shown that, though beneficial for electrochemical activity, the increased density of polar side chains deters the electronic properties in mixed conducting copolymers. 46,47 We thus selected DPP-30gT to endow the sensor channel with (i) sufficient affinity toward NO 2 molecules, (ii) a semicrystalline morphology promoting facile diffusion, and (iii) sufficient electronic charge transport needed to record the chemiresistive sensor response (Figure 1d). To control the blend morphology, we varied the compositional ratio between DPP-30gT and MI between 0 and 100 wt % MI.…”

“…Like other polymers mentioned above, these structures also suffer from poor environmental stability, including thermal stability. The common OMIECs are stable only up to 120 °C bakes, , with the recent exception of diketopyrrolopyrrole (DPP)-based OMIECs. − For instance, our group recently showed that with systematic control over the amount of polar side chains (triethylene glycol, TEG, which is known for enhancing gas affinity) − along the backbone, we can achieve optimal electrochemical modulation and unprecedented thermal stability (300 °C baking) in DPP copolymers . Motivated by the chemically tunable affinity toward polar molecules in these DPP-based copolymers, as well as their thermal stability, we are intrigued by whether such OMIEC systems can be employed for sensing toxic gases (especially NO 2 ) for real-time monitoring of industrial and domestic emissions.…”

“…We could thus deduce that, with the presence of TEG side chains, NO 2 gas is attracted toward the polymer backbone and easily abducts the electron from the latter, thus generating mobile holes which translate into a greater electrical conductivity in the device channel. 15−17 It is thus implied that semicrystalline films are preferred here (given that the electronic performance is retained, which is the case for DPP-30gT) 46 as the amorphous regions within the active sensing area will facilitate the diffusion of gas molecules into the film bulk (Figure 1d). 6,16 We then fabricated chemiresistive-type sensors and evaluated the NO 2 gas sensing properties of the DPP-30gT:MI blends.…”