White light and color tuning of OLED with phosphorous and fluorescent materials by solution process

Abstract

White light emissive organic light-emitting devices (OLED) with combination with phosphorous and fluorescent materials and that phosphorous materials and transition metal complexes as emissive materials by solution process have been discussed. Firstly, we employed poly(9,9-dioctylfluorene) (PFO)-based polymer light-emitting diodes (PLEDs) doped with red emissive phosphor tris(1-phenylisoquinoline) iridium (III) [Ir(piq)₃]. In order to change of the electroluminescent (EL) spectrum, PFO-based white PLEDs have been demonstrated utilizing changing the pulse width and frequency. The maximum luminance reached 4,800 cd/m² and the Commission Internationale de L'Eclairage (CIE) coordinates obtained the white emission of (0.33,0.35) at the pulse width and frequency of 100 ns and 1 kHz, respectively. Secondly, we investigated blue phosphorescent molecule of bis[(4,6-difluorophenyl)-pyridinato-N, C2'] (picolinate) iridium(III) (FIrpic) and the red europium complex of tris(dibenzoylmethane)-mono(4,7-di-phenylphenanthroline) europium(III) [Eu(DDP)₃phen] doped in poly(N-vinylcarbazole) (PVK). We demonstrated the white OLEDs employing the energy transfer from the host to dopants, showing the CIE coordinates of (0.31, 0.38). It was found that using Eu complexes for red dopants, it is easy to control the doping ratio and obtain the white emission. The OLEDs are fabricated by solution process on a glass substrate or polymeric substrate. Color tuning and white light emission are demonstrated by driving pulsed voltage.