Time-Resolved Structural Kinetics of an Organic Mixed Ionic-Electronic Conductor

Area of Science:

• Materials Science
• Polymer Science
• Physical Chemistry

Background:

• Organic mixed ionic-electronic conductors are crucial for device applications.
• Their transport properties are highly sensitive to structural changes.
• Device performance is limited by dynamic structural responses to electrochemical stimuli.

Purpose of the Study:

• To characterize the steady-state and transient structure of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) under operating conditions.
• To correlate structural dynamics with charge carrier kinetics.
• To understand factors limiting response times in organic electronic devices.

Main Methods:

• Multimodal time-resolved operando techniques were employed.
• Operando X-ray scattering (steady-state and time-resolved) was used to probe structural changes.
• Time-resolved spectroscopy investigated electronic charge carrier dynamics.

Main Results:

• Doping induced a lamellar expansion of 1.6 Å in PEDOT:PSS, followed by relaxation.
• Structural changes during doping/dedoping occurred at asymmetric rates, independent of potential.
• Structural transients were linked to polaron-bipolaron equilibrium in electronic charge carriers.

Conclusions:

• The study provides the first real-time observation of structural changes during doping/dedoping of conjugated polymers.
• Understanding these dynamics is key to optimizing response times in organic electronic devices.
• PEDOT:PSS exhibits complex structural responses influencing its electronic properties.