Title: Ultrafast Spectroelectrochemistry of Mixed Ionic\u2013Electronic Polymer Conductors<\/p>\n
By Fatma Altu\u011f<\/p>\n
Advisor: Associate Professor Burak \u00dclg\u00fct<\/p>\n
Date: September 8, 2025
\nTime: 18.00
\nThis is an online seminar. To request event details please send a message to department.<\/p>\n
Abstract:
\nElectron transfer and switching mechanisms in conducting polymers remain an open question. When conventional electrochemical techniques such as cyclic voltammetry are employed in isolation, the measured current inevitably contains contributions from both the polymer\u2019s redox processes and the capacitive charging current arising from voltage-dependent capacitance. Consequently, isolating the pure redox current requires additional deconvolution methods.
\nThe conventional understanding, repeatedly emphasized in the literature, is that electron transfer in conducting polymers proceeds via an ion-coupled mechanism, in which counter-ions from the electrolyte penetrate into the polymer to maintain charge neutrality.
\nIn this thesis, we challenge this conventional description by employing operando ultrafast cyclic voltammetry\u2013UV\u2013Vis spectroscopy, in which the potential is rapidly scanned within a defined range while the spectroscopic response is simultaneously recorded. By extending the sweep rate up to 200,000 V\/s, we aimed to suppress net counter-ion displacement. Under these conditions, the observed color change demonstrated that electron transfer can occur even in the absence of ion participation.
\nTo achieve this, operando ultrafast cyclic voltammetry\u2013UV\u2013Vis spectroscopy was utilized. The average spectroscopic responses obtained at ultrafast cycles were deconvoluted into their minimal components using principal component analysis (PCA), and the dependence of the resulting coefficients on sweep rate was systematically examined. Analysis of these coefficients revealed that, with increasing sweep rate, the relative lifetimes of oxidized and reduced states shift: counter-ion diffusion becomes increasingly limited, reducing doping efficiency and enhancing the contribution from the reduced state. Moreover, optical charge values derived from PCA coefficients approached steady-state at high sweep rates.
\nThese findings provide direct spectroscopic evidence that electron transfer in conducting polymers can proceed independently of ion motion under ultrafast potential modulation.
\nKeywords: Conducting polymers; Electron transfer; Ion-coupled mechanism; Ion-free electron transfer; Ultrafast cyclic voltammetry; Spectroelectrochemistry; Counter-ion diffusion; Principal component analysis (PCA).<\/p>\n","protected":false},"excerpt":{"rendered":"
Title: Ultrafast Spectroelectrochemistry of Mixed Ionic\u2013Electronic Polymer Conductors By Fatma Altu\u011f Advisor: Associate Professor Burak \u00dclg\u00fct Date: September 8, 2025 Time: 18.00 This is an online seminar. To request event details please send a message to department. Abstract: Electron transfer and switching mechanisms in conducting polymers remain an open question. [\u2026] <\/p>\n