Direct quantification of ion composition and mobility in organic mixed ionic-electronic conductors

Ion transport in organic mixed ionic-electronic conductors (OMIECs) is crucial due to its direct impact on device response time and fundamental operating mechanisms but are often assessed indirectly or rely on extra assumptions. Operando X-ray fluorescence (XRF) is a powerful, direct probe useful for elemental characterization of bulk OMIECs, and was employed to directly quantify ion composition and mobility in a model OMIEC, PEDOT:PSS, during device operation. The first cycle revealed slow electrowetting and cation-proton exchange. Subsequent cycles showed rapid response with minor cation fluctuation (~5%). Comparison with optical-tracked electrochromic fronts revealed a mesoscale structure dependent proton transport. The calculated effective ion mobility demonstrated thickness-dependent behavior, emphasizing an interfacial ion transport pathway with a higher mobile ion density. The decoupling of bulk and interfacial effects on ion mobility, and the decoupling of cation and proton tran..., We collected the XRF data in beamline 5-BMD, Advanced Photon Source, Argonne National Lab using operando XRF method that we developed. The UV-Vis results were collected with a halogen white light source (Ocean Optics, DH-2000-BAL) and an optical fiber to UV-visible (Ocean Optics, FLAME-S) spectrometers with 200 ms integration times., , **README: Direct quantification of ion composition and mobility in organic mixed ionic-electronic conductors**

[https://doi.org/10.5061/dryad.jdfn2z3j9](https://doi.org/10.5061/dryad.jdfn2z3j9)

In this dataset, we have included the operando X-ray fluorescence collected at beamline 5-BMD (Advanced Photon Source, Argonne National Laboratory). The X-ray energy used for the measurements was 15 and 15.2 keV. The UV-Vis results were collected with a halogen white light source and an optical fiber to Ocean Optics UV-visible spectrometers with 200 ms integration times.

 **Contact Information**

Name: R. Wu

Affiliations: Department of Biomedical Engineering, Northwestern University, Evanston, IL, USA

ORCID ID: [https://orcid.org/0000-0003-2666-6110](https://orcid.org/0000-0003-2666-6110)

Email: [[e-mail]](mailto:[e-mail])

**Description of the data and file structure**

There are two types of zip files. The ones starting with “XRF” are the operando XRF...