Charge Carrier Induced Structural Ordering And Disordering in Organic Mixed Ionic Electronic Conductors

Abstract

Operational stability underpins the successful application of organic mixed ionic‐electronic conductors (OMIECs) in a wide range of fields, including biosensing, neuromorphic computing, and wearable electronics. In this work, we investigate both the operation and stability of a p‐type OMIEC material of various molecular weights. Electrochemical transistor measurements reveal that device operation is very stable for at least 300 charging/discharging cycles independent of molecular weight, provided the charge density is kept below the threshold where strong charge‐charge interactions become likely. When electrochemically charged to higher charge densities, we observe an increase in device hysteresis and a decrease in conductivity due to a drop in the hole mobility arising from long‐range microstructural disruptions. By employing operando X‐ray scattering techniques, we find two regimes of polaron‐induced structural changes: 1) polaron‐induced structural ordering at low carrier densities, and 2) irreversible structural disordering that disrupts charge transport at high carrier densities, where charge‐charge interactions are significant. These operando measurements also reveal that the transfer curve hysteresis at high carrier densities is accompanied by an analogous structural hysteresis, providing a microstructural basis for such instabilities. This work provides a mechanistic understanding of the structural dynamics and material instabilities of OMIEC materials during device operation.This article is protected by copyright. All rights reserved

Gate bias modulation towards organic electrochemical transistors with ultra-high cycling stability

“…32–36 Above all, advanced OMIEC synthesis, additive engineering, and solid electrolyte utilization have remarkably enhanced cycling stability, but OECTs with extremely stable cycling characteristics are still missing, which is indispensable for commercialization. 37–41…”

Extracting Structural Data from MALDI-ToF Mass Spectrometry Analysis of Alternating Conjugated Polymers – A Case Study on PBTTT Derivatives

“…35 Next to molecular weight separation, prep-GPC was also found to remove Pd traces resulting from the polymerization catalyst, with a noteworthy positive effect on device performance. 36,37 For a homopolymer such as P3HT, the various molecular weight samples are not expected to differ significantly in terms of chemical structure. When looking at alternating copolymers, however, there might be differences in the chemical structures of varying molecular weight samples due to a different ratio of homocoupling and diverse end-groups.…”

“…This approach has been shown to have a significant effect on OPV device efficiency. , Furthermore, GPC fractionation can be applied as well to study the effect of molecular weight on polymer transport properties and microstructure . Next to molecular weight separation, prep-GPC was also found to remove Pd traces resulting from the polymerization catalyst, with a noteworthy positive effect on device performance. , …”