The experiment is designed for a junior-level materials engineering laboratory course. Students will measure the photoluminescence spectra of a semiconducting polymer. They will measure and compare the photoluminescence spectrum of a liquid solution of a semiconducting polymer and the photoluminescence spectrum of a solid film of the same polymer.

The unique feature of this experiment is the use of a semiconducting polymer that is soluble in the semiconducting state. This new class of materials opens up a range of new possibilities, simple fabrication procedures, and applications for electronic and opto-electronic devices. See R.H. Friend, R.W. Gymer, et al., "Electroluminescence in conjugated polymers," Nature 397 (1999) 121-128. The materials also make possible interesting educational possibilities. In comparison to materials with infra-red bandgaps, use of a di-alkoxy-PPV polymer with a visible electronic bandgap and a visible photoluminescence spectrum make it easier for the students to connect optical concepts to data recorded in the form of a spectrum.

The procedure consists of shining UV light onto each sample and recording the photoluminescence spectrum using the Ocean Optics spectrometer. Students then plot their results and compare the spectra.

Prepared by David Braun and Linda Vanasupa of Cal Poly State University, San Luis Obispo.
See http://www.ee.calpoly.edu/~dbraun/polyelec/