“…The high spatial resolution and wide environmental adaptability of AFM make this technique highly advantageous for operando characterization of OMIECs. Spatial resolution at the molecular level has been reported for structural characterization at the liquid/solid interface . In situ AFM has also been applied on polyelectrolytes to study the swelling in water vapor and the relaxation process in aqueous solutions .…”
Section: Scanning Probe Techniquesmentioning
confidence: 99%
“…Spatial resolution at the molecular level has been reported for structural character-ization at the liquid/solid interface. 404 In situ AFM has also been applied on polyelectrolytes to study the swelling in water vapor 405 and the relaxation process in aqueous solutions. 406 In addition, the interfacial morphology changes during electrochemical polymerization of EDOT has been observed by in situ AFM.…”
Operando characterization plays an important role in revealing the structure− property relationships of organic mixed ionic/electronic conductors (OMIECs), enabling the direct observation of dynamic changes during device operation and thus guiding the development of new materials. This review focuses on the application of different operando characterization techniques in the study of OMIECs, highlighting the time-dependent and bias-dependent structure, composition, and morphology information extracted from these techniques. We first illustrate the needs, requirements, and challenges of operando characterization then provide an overview of relevant experimental techniques, including spectroscopy, scattering, microbalance, microprobe, and electron microscopy. We also compare different in silico methods and discuss the interplay of these computational methods with experimental techniques. Finally, we provide an outlook on the future development of operando for OMIEC-based devices and look toward multimodal operando techniques for more comprehensive and accurate description of OMIECs.
“…The high spatial resolution and wide environmental adaptability of AFM make this technique highly advantageous for operando characterization of OMIECs. Spatial resolution at the molecular level has been reported for structural characterization at the liquid/solid interface . In situ AFM has also been applied on polyelectrolytes to study the swelling in water vapor and the relaxation process in aqueous solutions .…”
Section: Scanning Probe Techniquesmentioning
confidence: 99%
“…Spatial resolution at the molecular level has been reported for structural character-ization at the liquid/solid interface. 404 In situ AFM has also been applied on polyelectrolytes to study the swelling in water vapor 405 and the relaxation process in aqueous solutions. 406 In addition, the interfacial morphology changes during electrochemical polymerization of EDOT has been observed by in situ AFM.…”
Operando characterization plays an important role in revealing the structure− property relationships of organic mixed ionic/electronic conductors (OMIECs), enabling the direct observation of dynamic changes during device operation and thus guiding the development of new materials. This review focuses on the application of different operando characterization techniques in the study of OMIECs, highlighting the time-dependent and bias-dependent structure, composition, and morphology information extracted from these techniques. We first illustrate the needs, requirements, and challenges of operando characterization then provide an overview of relevant experimental techniques, including spectroscopy, scattering, microbalance, microprobe, and electron microscopy. We also compare different in silico methods and discuss the interplay of these computational methods with experimental techniques. Finally, we provide an outlook on the future development of operando for OMIEC-based devices and look toward multimodal operando techniques for more comprehensive and accurate description of OMIECs.
“…It should be noted here that these spectral changes were not due to the dissolution of the organic semiconductor molecule into the IL. While other organic semiconductors such as rubrene were easily dissolved into ILs 14 , the DNBST-based OFETs were stable in ILs. Fig.…”
Section: Resultsmentioning
confidence: 99%
“…IL-gated EDL-OFETs were first reported by Takeya’s group in 2008 using rubrene single crystals 9 . This field of study has since expanded to include other organic semiconductors, such as octathio[8]circulene 10 , [7]phenacene 11 , pentacene 12 – 14 , and fullerene 13 . The IL species is one of several important factors determining the carrier mobility ( μ ) of a device 15 – 17 .…”
The interface of organic semiconductor films is of particular importance with respect to various electrochemical devices such as transistors and solar cells. In this study, we developed a new spectroscopic system, namely electrochemical attenuated total reflectance ultraviolet (EC-ATR-UV) spectroscopy, which can access the interfacial area. Ionic liquid-gated organic field-effect transistors (IL-gated OFETs) were successfully fabricated on the ATR prism. Spectral changes of the organic semiconductor were then investigated in relation to the gate voltage application and IL species, and the magnitude of spectral changes was found to correlate positively with the drain current. Additionally, the Stark shifts of not only the organic semiconductor, but also of the IL on the organic semiconductor films were detected. This new method can be applied to other electrochemical devices such as organic thin film solar cells, in which the interfacial region is crucial to their functioning.
“…As electronic devices are composed of multiple materials and layers, their performance and functions strongly depend on not only the individual components but also the constituent interfaces. − Ionic liquids (ILs) are frequently incorporated in devices, such as solar cells, − light-emitting diodes, − and field-effect transistors (FETs), − and it has been reported that the semiconductor–IL interface plays a crucial role in protecting against oxygen- and moisture-adsorption-induced degradation, optimizing the morphology and energy levels of semiconducting layers and accumulating a high density of carriers in interfacial semiconducting layers. Accordingly, the characterization of the interfacial structures and electronic states at the atomic and/or molecular levels to clarify the relationship between the interfacial properties and device performances and, thereby, improve the device performance is paramount.…”
Understanding semiconductor–ionic-liquid (IL)
interfaces
is essential for achieving high-performance electronic devices. However,
it is difficult to analyze the interfacial electronic states, particularly
in the highest occupied molecular orbital (HOMO), because the probing
depth of conventional photoelectron spectroscopy is limited to ∼1
nm. Here, we employ photoelectron yield spectroscopy to probe the
interfacial electronic states of pentacene submonolayer thin films
underneath IL layers and investigate the impact of the IL layers on
the shapes and energy levels of the HOMO for the pentacene submonolayer
thin films. With increasing the thickness of the IL layers, the density
of states on the HOMO peak broadened, indicating that the IL layers
induced an energetic disorder in the density of states of the pentacene
submonolayer thin films. In addition, the peak top energy of the HOMO
peak and the ionization energy gradually shifted toward higher energies
as the IL thickness increased, which is attributed to the shifts in
the vacuum level and the increase in the polarization energy at the
interfaces. This work demonstrates that the photoelectron yield spectroscopy
(PYS) technique can adequately access the electronic states at heterointerfaces,
highlighting its significant potential for application in the interfacial
characterization of devices.
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