Optical characterization of polychromatic organic light emitting diodes

Abstract

Luminance and quantum yields of organic light emitting diodes (OLEDs) are generally calculated by using a hypothetic monochromatic emission even though the actual external emission is lower than the internal emission because of internal reflection, and is polychromatic. For organic materials, we present the effects of the total internal reflection on quantum yields. Calculations for the luminance and the efficiency of an ideal pseudomonochromatic source are compared with those for a real polychromatic source. While we demonstrate that the calculation of the yield is practically unchanged whatever hypothesis is used, we do show, however, that by assuming that the source is pseudomonochromatic, the luminances of green and blue OLEDs are overvalued or undervalued by a factor of 4, respectively. © 2005 American Institute of Physics.