Chemistry Department Seminar

"“High Resolution Optical spectroscopy of charge transfer doping and electrochemical processes in polymer semiconductor devices”"

Presented by Riccardo Di Pietro, University of Cambridge, U.K.

Monday, December 5, 2011, 11:00 am — Room 300, Chemistry Bldg. 555

We have developed a high sensitivity optical spectroscopy technique that allows monitoring subtle changes of the optical absorption of an organic material at a sensitivity level of few parts in 10000 as a function of time. This technique allows in-situ spectroscopic investigation of some of the key electronic processes in fully functional device structures.
We successfully applied the technique to study the mechanism of charge transfer doping of conjugated polymer films by MoO3. We were able to quantify doping efficiency and investigate the stability of the doped device in time, correlating the decrease in doping efficiency to the changes in the molybdenum trioxide energetic structure.
We have also used the technique to investigate the mechanism for electron trapping in n-type organic FETs of poly{[N,N9-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,59-(2,29-bithiophene) (P(NDI2OD-T2)). The fundamental role of the atmosphere composition in the stressing mechanisms is determined by comparing device stability in vacuum and in air, and the results are analysed in view of possible electrochemical reactions involving charged polymer units and both O2 and H2O.

Hosted by: Matthew Bird

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