Improvement of radiative efficiency and wavelength-tuning by TPD-doping in organic light emitting diode using Poly [methylmethacrylate-co-(7-(4- trifluoromethyl)coumarin acrylamide)] (PCA)

Abstract

We fabricated polymer light-emitting diodes (PLEDs) using a low-weight-molecular-doped luminescent material with a ?max in the ultraviolet region. A single layer PLED without low-weight-molecular-doping does not reveal any electroluminescence (EL) signal at all. However, a PLED with doping clearly shows EL signals. This indicates that carrier injection as well as radiative efficiency can be drastically improved by low-weight-molecular-doping. In addition, multilayered PLEDs are found to be very effective to further improve carrier injection. © 2008 IOP Publishing Ltd.