Fabrication of white organic light-emitting diodes by co-doping of emissive layer

Abstract

Efficient white light emission by mixing of red emission from (Ir-BTPA) [bis(2-(2’-benzothienyl) pyridinato-N,C³’) (acetyl-acetonate) iridium(III) and greenish blue from (FIrPic) [bis(2-(4,6-difluorophenyl)pyridinato-N,C²’) iridium(III)] has been studied. Ir-BTPA and FIrPic are co-doped into a 4, 4’ bis 9 carbozyl (biphenyl) (CPB) host. The device emission colour is controlled by varying dopant concentration. Photoluminescence (PL), electroluminescence (EL) and colour coordinates have been studied as a function of applied voltage. The EL spectra of the devices with the co-doped emissive layer show three emission peaks at 469, 500 and 611 nm. Commission Internationale de l'Eclairage (CIE) coordinates of the devices are 0.27, 0.32 at 18 V and are well within the white region.