Highly efficient blue emitting materials based on indenopyrazine derivatives for OLEDs [Invited]

Two indenopyrazine compounds for organic light emitting diodes were synthesized with phenanthrene or pyrene side groups that have high photoluminescence (PL) quantum efficiency (QE); 6,6,12,12-Tetraethyl-2,8-di-phenanthren-9-yl-6,12-dihydro-diindeno[1,2-b; 1',2'e] pyrazine (PA-EIP) and 2-(10b,10c-Dihydro-pyren-1-yl)-6,6,12,12-tetraethyl- 8-pyren-1-yl-6,12-dihydro-diindeno[1,2-b;1',2'-e]pyrazine (PY-EIP). The PL spectra of PA-EIP and PY-EIP in film state were 440 nm and 468nm in the blue region, respectively. T-d values for PA-EIP and PY-EIP were very high at 432 degrees C and 441 degrees C. T-m values were 385 degrees C and 390 degrees C for PA-EIP and PY-EIP. When the synthesized compounds were used as emitting layers in non-doped OLED devices, PA-EIP and PY-EIP showed luminance efficiencies of 1.35 and 5.15 cd/A, power efficiencies of 0.69 and 2.81 lm/W, and CIEs of (0.17, 0.15) and (0.19, 0.30), respectively. This result shows that efficiency of final emitter increases with increasing efficiency of side group. Additionally, in the solution-processed white OLED devices using PY-EIP as one of emitting materials, the device showed high luminance efficiency of 3.95 cd/A, power efficiency of 2.45 lm/W and CIE value of (0.269, 0.294) at 6 V. (C) 2014 Optical Society of America