Simple assembling of organic light-emitting diodes for teaching purposes in undergraduate labs

Abstract

Electroluminescent organic molecules and polymers have emerged as advanced materials used to fabricate organic light-emitting diodes (OLEDs) whose unique technological features could revolutionize the industry of flat-panel displays. Although in many cases these novel organic materials combine low cost and ease of processing, OLEDs fabrication for educational purposes has rarely been reported. In this work, we report a simple and inexpensive method to fabricate organic electroluminescent devices intended for educational purposes at the undergraduate level of physics, chemistry and material sciences. For ease of fabrication the cathode in the diode structure was formed by either an alloy of Bi-Pb-Cd-Sn or by a Ga-In alloy in the liquid phase, or simply by silver paint, whereas we used ITO (Indium Tin Oxide) deposited on glass substrates as the anode. Substrates of flexible plastic were also used. The OLEDs were fabricated using the spin-coating technique with solutions of the fluorescent materials Alq$_3$ and MEH:PPV, as well as the phosphor complex Ru(bpy)$_3$. We report measurement data on current-voltage curves, luminescence, and efficiencies obtained by students fabricating and testing the devices under normal room conditions.