Efficiency Limits for Emissive Polymer LEDs

Measurements of conjugated polymer photoluminescence yield are often motivated by their implications for the emissive efficiency of electroluminescent devices based upon the same material. We report studies of phenylenevinylene polymers that enable us to identify two important mechanisms, one intrinsic and one extrinsic, which reduce the luminescence efficiency. We also show that one of the premises underlying the presumed correlation between electroluminescence and photoluminescence quantum yields is incorrect.