Effect of electron mobility of the electron transport layer on fluorescent organic light-emitting diodes

The charge balance mechanism in green fluorescent organic light-emitting diodes is investigated for different electron transport layers (ETLs) and electron mobilities. Carrier accumulation and an increase in the exciton recombination probability are shown to be critical for improving the current and power efficiencies by aligning the bands at the interface between the emitting layer (EML) and ETL. The peak in the electroluminescence (EL) spectra was found to shift slightly in response to changes in the width of the emission zone and reflected the electron mobility of the ETL. Higher electron mobility resulted in a wider recombination zone in the EML that was manifested by a blue-shift of the EL peak.