Although few lighting products available on the market use organic light emitting diodes (OLED) , they are considered today’s most promising display technology. One major obstacle is the lack of understanding of the electroluminescence processes on the single molecule level.
We developed and built up a low-temperature scanning tunneling microscope (LT-STM) that is equipped with a parabolic mirror collecting photons emitted from the tunnel junction from a large solid angle. The collected light is then be guided to a spectrometer via an optical fiber.
The first part of this master thesis comprises extensive test measurements of both the optical path and the LT-STM setup. In the second part, we plan to measure light emission from surface plasmons localized in the gap between the STM tip and the metal surface. This will allow the identification of relevant frequencies for spectral matching with the molecular emission. Further, the adsorption geometry on noble metal surfaces will be measured for specifically designed optically active molecules.
Left: LT-STM with optical access. Right: Light emission from single molecules excited by tunneling electrons.