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.