Precise measurement of external quantum efficiency of organic light-emitting devices

We report on the direct measurement of the external quantum efficiency of electroluminescence of organic light-emitting devices with different emission colors and patterns using an integrating sphere and a highly sensitive charge-coupled device spectral analyzer. Using this direct-measurement method, precise external quantum efficiency can be obtained more easily and more quickly than using the conventional luminance-conversion method. This method is shown to be very useful for determining the external quantum efficiency of organic light-emitting devices.