The work horse for all our electrochemical experiments is a CHI760E bipotentiostat from CH-Instruments. The device is capable of performing standard techniques, like cyclic voltammetry (CV), differential pulse voltammetry (DPV), chronoamperometry (CA), various frequency-based measurement methods and many more. A full list of available techniques can be found on the homepage of the manufacturer (https://chinstruments.com/chi700.shtml).
Besides this apparatus, we are equipped with two fully functional legacy potentiostats from Bioanalytical Systems: A BAS 100B Electrochemical Analyzer and a BAS CV-50W Voltammetric Analyzer. Both machines were generously provided to us by the AK Speiser, University of Tübingen (https://www.echem.uni-tuebingen.de/index.html/).
By using the lock-in technique, our homebuilt EMAS setup (potential-modulated absorption spectroscopy) is able to characterize thin layers of different materials, like nanocrystals (NC) or organic semiconductors (OSC) deposited on a transparent-conducting-oxide electrode (TCO electrode) regarding their spectroelectrochemical properties. Information about the energetic localization of electronic states involved in optical transitions can be obtained from the measured data.
The setup consists of an APEX2 QTH lamp (Oriel Instruments) with a spectrum that covers the UV-VIS-NIR range, a Cornerstone 130 extended range monochromator (Oriel Instruments) capable of handling the lamp spectrum, a homebuilt-3D-printed air-tight spectroelectrochemical measurement cell, the previously mentioned CHI760E bipotentiostat (CH Instruments), a MFLI lock-in amplifier (Zurich Instruments) covering a frequency range from DC to 500 kHz, a homebuilt faraday cage, various lenses (Thorlabs) for handling the optics and biased detectors (Thorlabs) that allow measuring over the UV-VIS-NIR range.
Utilizing the second channel of our CHI760E bipotentiostat we are able to measure ECG (electrochemical gating) by a combination of several consecutive steps of chronoamperometry and cyclic voltammetry. Thin films of NC or OSC are coated on an interdigitated electrode (IDE) which is then inserted into a full-glass electrochemical measurement cell. With respect towards the reference electrode the fermi level within the film then is shifted. From the measured data we can obtain information about the presence of oxidizable or reducible states, as well as whether these states contribute to the overall conductivity of the film when being oxidized or reduced. Measurements are always performed in a faraday cage which is placed in a nitrogen-filled glovebox.
Besides the aforementioned, more advanced techniques, we also measure standard cyclic voltammetry or differential pulse voltammetry experiments of either solutions by using several disc electrodes, or thin films coated on transparent conducting oxides or disc electrodes. These measurements also take place in the nitrogen-filled glovebox using the same measurement cell shown in the ECG section.