Efficient polymer white-light-emitting diodes with a phosphorescent dopant

Abstract

Efficient polymer white-light-emitting diodes (WPLEDs) with an active polymer layer have been demonstrated. The white emission consists of two emission bands in the blue and yellow ranges. The blue polymer is a host (PFO) and the yellow dopant is a phosphorescent dye of Ir(CzBPPF) 2 (PZ), i.e. Iridium(III) bis(2,4-diflurophenyl-2-pyridine-4-phenyl-p-carbarzole)(2-(4H-1,2,4-triazol-3-yl)-pyridine). When the doping concentration of Ir(CzBPPF) 2 (PZ) is 2 wt%, pure white light is obtained, which possesses stable white light CIE coordinates, efficiency of 5.6 cd A −1 (9.5 V) and luminance of 7656 cd m −2 (14 V). The EL process in the device was proved mainly to be the charge trap mechanism.

Achieving highly efficient white organic light-emitting diodes with reduced efficiency roll-off

“…blue and yellow or orange) or primary colours (red, green and blue). Accordingly, various methods have been proposed to realize this goal [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21]. A key requirement for achieving high efficiency is that all electrically generated excitons must be employed for emission.…”

Spectral studies of thin films based on poly(N-vinylcarzole) and red dopant

“…Recently, doping of organic lightemitting layers with fluorescent or phosphorescent dyes has become a promising method. Some groups have also used such doping schemes to study the doping effects in various material systems [9][10][11]. In these doped systems, the luminescence from a guest dopant molecule would result from either energy transfer of an exciton formed in the host to the guest molecule or sequential trapping of a hole and an electron by the guest molecule.…”

Site Isolation in Phosphorescent Bichromophoric Block Copolymers Designed for White Electroluminescence

“…For example, successful demonstrations of polymer WOLEDs have been based on blends of fluorescent polymers, [9] polymers incorporating multiple fluorescent emitters in their side chains [10,11] or their backbone [12,13] and fluorescent polymers doped with small molecule phosphorescent emitters. [14][15][16] However, these devices are generally fluorescent systems with limited internal quantum efficiencies or doped phosphorescent systems with poor stability. Furthermore, the occurrence of energy transfer limits the amount of low energy dopant that can be incorporated into these polymers, which affects their intrinsic efficiency.…”