CHEMISTRY DEPARTMENT SEMINAR
Ph.D. THESIS DEFENSE
X-RAY PHOTOELECTRON SPECTROSCOPY FOR CHEMICAL AND ELECTRICAL CHARACTERIZATION OF DEVICES EXTENDED TO LIQUID/SOLID INTERFACES
Pınar Aydoğan Göktürk
Supervisor: Prof. Dr. Şefik Süzer
Understanding of electrical and electrochemical devices in operating conditions is vital for development of new technologies. Many important characteristics that determine the performance of such devices lie on their surfaces and interfaces which significantly deviate from the bulk properties. However, particularly for the liquid based devices, carrying out surface analysis is challenging and requires highly sophisticated instrumentation. In this doctoral thesis, we used the well-known Voltage Contrast X-Ray Photoelectron Spectroscopy to follow both electrical and chemical properties of nonaqueous and non-volatile liquids in devices used particularly for electrowetting applications. The technique was previously applied by us to investigate electrical characterization of graphene based solid-state devices under operating conditions. Establishing this novel technique by using both DC and AC excitation has opened up a new perspective to assess the performance of other device geometries, including liquid/solid and liquid/vacuum interfaces. In the present work, we have focused on a particular and commonly used electrowetting on dielectric (EWOD) geometry and used two types of UHV compatible non-aqueous liquids, namely ionic liquid DEME-TFSI and Polyethylene glycol as representative of two extreme cases in terms of ionic content. We have aimed to unravel the potential developments on liquid, dielectric surfaces as well as the liquid/solid interfaces during AC and DC excitation in a chemically resolved fashion.
Date: December 20, 2018 (Thursday)
Place: Faculty of Science Building, B Block, Meeting Room #SB-115