High efficiency green phosphorescent organic light emitting device with (TCTA/TCTA0.5TPBi0.5/TPBi): Ir(ppy)3 emission layer

A new high efficiency green light emitting phosphorescent device with an emission layer consisting of {4,4',4''-tris(N-carbazolyl)-triphenylamine[TCTA]/TCTA0.5TPBi0.5/1,3,5-tris(N-phenylbenzimiazole-2-yl)benzene[TPBi]}:tris(2-phenylpyridine)iridium(III)[Ir(ppy)3] was fabricated and its electroluminescence characteristics were evaluated in comparison with those of devices with emission layers made of (TCTA0.5TPBi0.5):Ir(ppy)3 and (TCTA/ TPBi):Ir(ppy)3.The device with the emission layer consisting of (TCTA/TCTA0.5TPBi0.5/TPBi):Ir(ppy)3 showed a luminance of 11,000 cd/m2 at an applied voltage of 8 V and maximum current efficiency of 63 cd/A under a luminance of 500 cd/m2. The peak wavelength in the electroluminescent spectral and color coordinate on the Commission Internationale de I'Eclairage(CIE) chart were 513 nm and (0.31, 0.62) in this device, respectively. Under a luminance of 10000 cd/m2, the current efficiency of this device was 55 cd/A, which is 1.4 and 1.1 times better than those of the devices with the emission layers made of (TCTA0.5TPBi0.5):Ir(ppy)3 and (TCTA/TPBi):Ir(ppy)3, respectively.