Development and evaluation of new ultra-fast spectroscopic detection methods

Development and evaluation of new ultra-fast spectroscopic detection methods for the characterization of excited electronic states and the transfer of energy in molecular electronic devices


The project aims at setting up a joint project involving the Laboratory of Photochemistry and Spectroscopy (LPS) at KULeuven and the Laboratory of Quantum Optics (LKO) at the University of Nova Gorica (Slovenia). Organic photovoltaic cells and organic light emitting diodes consist of thin films of carbon based molecules and convert light into a voltage or viceversa. While their fabrication is cheaper than inorganic devices, their efficiency is still much below the theoretical limit. Their improvement requires knowledge of the yield and rate of formation and decay of intermediate species such as excited states, holes and electrons eg by monitoring the light they absorb. As this requires high concentration of such species and hence a large power density of laser pulses, artifacts can easily occur.

We will develop and test two alternative methods to monitor the dynamics of intermediate species. In a first one, a laser pulse creates an excited state which is ionized by a second pulse, impinging the sample after a selected time delay. The ejected electrons are collected in the function of the time delay and of their energy. In the second method, the delayed laser pulse creates a scattered light with a frequency shifted by the vibration frequency of the excited species, which is very specific and depends on the strengths of the bond. These methods can probe the total number of excited species rather than their concentration. They provide direct information on the relevant energy levels of the material under scrutiny and on the strength of the bounds of the excited species.


prof. dr. Giovanni De Ninno (UNG)
dr. Barbara Ressel (UNG)
Matija Stupar (UNG)


The project was funded by the “Javna agencija za raziskovalno dejavnost Republike Slovenije”.