Temperature- and field-dependent quantum efficiency in tris-(8-hydroxy) quinoline aluminum light emitting diode

摘要

Temperature-and field-dependent electroluminescence and quantum efficiency have been investigated in tris-(8-hydroxy) quinoline aluminum (Alq_3) light emitting diode over the temperature range from 10K to 300K. It has been observed that up to a certain temperature luminescence intensity decreases with decreasing temperature and then saturated in the low temperature region. The quantum efficiency increases with decreasing temperature and finally reaches to almost a constant value. At lower applied voltage, two peaks have been observed in the quantum efficiency with temperature. The two peaks are attributed due to deep trap levels (high temperature regime) and shallow trap levels (low temperature regime) in Alq_3.