Synthesis and Characterization of Cadmium Complex and Its Application in Organic Light Emitting Diodes (OLEDs)

A new electroluminescent cadmium complex Cadmium (2,2 bipyridine) 2 methyl 8-hydroxyquinoline Cd(Bpy)mq has been synthesized and characterized with UV-spectroscopy, PL-spectroscopy, FTIR, TGA, for its application in organic light emitting diodes (OLEDs). The absorption spectra of this material shows maxima at 320 and 395 rim. It may be attributed to pi-pi* transition. Photoluminescence spectra for this material showed the most intense peak at 507 nm and the time resolved photoluminescence spectra showed two life time components. The decay times of the first and second component were 4.6 ns and 15.40 ns respectively. This material shows thermal stability up to 350 degrees C. An OLED device was fabricated using this material by thermal evaporation. This device consists of many layers such as hole transport layer (HTL), emissive layer (EML), hole blocking layer (HB), electron transport layer (EL) electron injection layer (EIL) and cathode. Each layer has thickness of a few nanometers. The structure of the device is ITO/alpha-NPD(40 nm)/Cd(Bpy)mq(35 nm)/BCP(6 nm)/Alq(3)(30 nm)/LiF(1 nm)/AI(100 nm). This device exhibited a luminescence peak at 555 nm. The maximum luminescence of the device was 219 cd/m(2) at 27 V. The maximum current efficiency of OLED was 0.08 cd/A and maximum power efficiency was 0.01 lm/W at 21 volt.