Presented here is an overview of the current status of our work on scanning-tunneling-microscope-based (STM) spectroscopy and electroluminescence (EL) excitation to study the physical and electronic structure of organic materials used in organic light-emitting devices (OLEDs). By these means we probe the critical device parameters in charge-carrier injection and transport, i.e. the height of the barrier for charge-carrier injection at interfaces between different materials and the energy gap between positive and negative polaronic states. In combination with optical absorption measurements, we gauge the exciton binding energy, a parameter that determines energy transport and electroluminescence efficiency. In STM experiments involving organic electroluminescence excitation the tip functions as an OLED electrode in a highly localized fashion, allowing one to map the spatial distribution of the EL intensity across thin-film samples with nanometer lateral resolution as well as to measure the local EL emission spectra and the influence of thin-film morphology.
IBM J. Res. Develop. vol. 45, no. 1, p. 89-100, 2001.
By: S.F. Alvarado, L. Rossi, P. Müller, P. F. Seidler, and W. Rieß
Published in: RZ3272 in 2001
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