Conjugated Polyelectrolyte Blends for Highly Stable Accumulation-Mode Electrochemical Transistors

Abstract

Counterion exchange has been introduced as a method to modify properties of anionic conjugated polyelectrolyte (CPE) blends. Blending of two self-doped CPEs having metallic and semiconducting behavior has been achieved from two different solvents, by exchanging the counterion of the metallic component. Different blending conditions lead to films exhibiting different optical properties, depending on the aggregation states of the CPEs. Conductance responses for the blends showed the opportunity to tune threshold voltage of the films both by blending and counterion exchange. Therefore, the blends have been exploited for the fabrication of accumulation mode organic electrochemical transistors. These devices exhibit short switching times and high transconductance, up to 15.3 mS, as well as high stability upon fast pulsed cycles, retaining 88% of the drain currents after 2 × 103 cycles.

Analysis of Conjugated Polymers Conductivity by in situ Electrochemical‐Conductance Method

“…The first channel of the bipotentiostat is used in the standard three electrode mode, while the second channel is used to apply the Δ V between the both parts of the IDME . In‐situ conductivity measurements of several conducting polymers by means of the bipotentiostat mode has been obtained . Nonetheless, in this configuration it must be assumed that the difference between the faradaic current ( i f ) detected on both electrodes is negligible in comparison with the i d this supposition is not always true and control experiment should be carried out to confirm the obtained results.…”

“…[81] Insitu conductivity measurements of several conducting polymers by means of the bipotentiostat mode has been obtained. [81][82][83][84][85][86][87] Nonetheless, in this configuration it must be assumed that the difference between the faradaic current (i f ) detected on both electrodes is negligible in comparison with the i d [82] this supposition is not always true and control experiment should be carried out to confirm the obtained results.…”

“…The response is characterized by a sigmoidal transition from a neutral (non‐conducting) to an oxidized or reduced state (conducting) in a G vs E plot, which can be correlated with the corresponding voltammogram. (Figure ) . These curves can be depicted in two formats; linear or logarithmic scale for the conductance values.…”

“…Furthermore, the derivative plot ( dG/dV or dσ/dV vs E ) let to recognize the presence of different charged states . The difference between the initial potential of the conducting state and the redox process, is due to the chemical and electronic structure of the polymers, as well as the doping conditions . In conjugated polymers the conductivity is explained by the bipolaron model or the mixed‐valence model .…”

“…(Figure 8). [79,84,116,117] These curves can be depicted in two formats; linear or logarithmic scale for the conductance values. In some cases, is important to analyze the semi-conducting region (10 À 4 � σ � 10 À 0 Ω À 1 cm À 1 ) in order to extract important information about the electrical material behavior.…”