The Role of Long‐Alkyl‐Group Spacers in Glycolated Copolymers for High‐Performance Organic Electrochemical Transistors

Abstract

Semiconducting polymers with oligoethylene glycol (OEG) sidechains have attracted strong research interest for organic electrochemical transistor (OECT) applications. However, key molecular design rules for high-performance OECTs via efficient mixed electronic/ionic charge transport are still unclear. In this work, new glycolated copolymers (gDPP-TTT and gDPP-TTVTT) with diketopyrrolopyrrole (DPP) acceptor and thiophene (T) and vinylene (V) thiophene-based donor units are synthesized and characterized for accumulation mode OECTs, where a long-alkyl-group (C 12 ) attached to the DPP unit acts as a spacer distancing the OEG groups from the polymer backbone. gDPP-TTVTT shows the highest OECT transconductance (61.9 S cm -1 ) and high operational stability, compared to gDPP-TTT and their alkylated counterparts. Surprisingly, gDPP-TTVTT also shows high electronic charge mobility in a field-effect transistor, suggesting efficient ion injection/diffusion without hindering its efficient electronic charge transport. The elongated donor unit (TTVTT) facilitates hole polaron formation to be more localized to the donor unit, leading to faster and easier polaron formation with less impact on polymer structure during OECT operation, as opposed to the TTT unit. This is supported by molecular dynamics simulation. These simultaneously high electronic and ionic charge-transport properties are achieved due to the long-alkyl-group spacer in amphipathic sidechains, providing an important molecular design rule for glycolated copolymers.

Highly Efficient Mixed Conduction in a Fused Oligomer n‐Type Organic Semiconductor Enabled by 3D Transport Pathways

“…[ 52 ] Confirming that the two gTNR derivatives can be reduced efficiently in aqueous solution, we also notice a more intense polaron absorption band for lgTNR than for bgTNR at identical electrochemical potentials (Figure 3f) which could indicate a better ability for the linear derivative to accommodate stored charges in the semiconductor film compared to the branched counterpart under these conditions. [ 53 ] We also investigated the polaron stability of the two semiconductors by monitoring the intensity changes of UV‐vis–NIR absorption spectra during continuous electrochemical cycling. Both lgTNR and bgTNR exhibit moderate polaron stability with a retention of 80% and 70% optical density after ten cycles (Figure S8, Supporting Information), which corroborate the morphological changes observed after cycling, and the OECT operational stability discussed below.…”

Impact of the Molecular Structure of Oligo(ethylene glycol)-Incorporated Y-Series Acceptors on the Formation of Alloy-like Acceptors and Performance of Non-Halogenated Solvent-Processable Organic Solar Cells

“…Detailed procedures for Y- n C-4O synthesis, material characterizations, device fabrication, and measurements are described in the Supporting Information. Intermediate compounds for the guest SMAs were synthesized according to previous literature. , The poly­(3,4-ethylenedioxythiophene):poly­(styrenesulfonate) (PEDOT:PSS, Clevios P VP AI 4083) solution, used to prepare the hole-transporting layer, was purchased from Heraeus (Germany). PM6 and Y6, used as the polymer donor and host SMA, respectively, were purchased from Derthon OPV.…”

A guide for the characterization of organic electrochemical transistors and channel materials

“…Another study from the same team demonstrated the preferential interactions of ions with the donor (anions) or acceptor (cations) units of glycolated diketopyrrolopyrrole (DPP)-based copolymers and how the side chain nature could influence such interactions for maximized OECT performance. 161 Furthermore, MD simulations were successfully used to study phase transitions in OMIECs amorphous phase during electrochemical doping and ion injection, [162][163][164] despite relying on AMBER force a non-validated force field model for the systems investigated and generally used to model nonconjugated system. 165 To accurately model OMIECs, a possible alternative is to reparametrize backbone dihedral angles to capture more accurately the torsional behavior of the conjugated units.…”