Color optimization of red organic light emitting diodes (OLEDs) through dihydroxyphenyl-substituted zinc porphyrins emitters

Abstract

Abstract Four tetrakis (dihydroxyphenyl) Zinc(II) porphyrin (Zn-TDHPP) were successfully synthesized and used as fluorescent materials in organic light-emitting diodes (OLEDs). Devices were fabricated with an indium tin oxide(ITO)/poly (3,4-ethylenedi-oxythiophene):poly (styrenesulfonate) (PEDOT:PSS) (55 nm)/polyvinylcarbazole (PVK):(2-(4-biphenyl)-5-(4-t-butylphenyl)1,3,4-oxadiazole) (PBD):Zn-TDHPP derivatives (80 nm)/Al (150 nm). The resultant devices had peak emissions ranging from 602 nm to 645 nm. It has been shown that with modification of Zn-TDHPP molecule having specific backbone with different functional groups R (R OH, COOH), we could change and control its optical properties such as band gap energy, photoluminescence (PL) and electroluminescence (EL) spectra along with its electrical properties such as current diagram of OLED devices. In addition, it is possible to modify Commission Internationale de l’Eclairage (CIE) coordinates of EL spectrum of fabricated OLED devices for application in the display industry. We used dichloromethane bath and Ultra-Violet laser (405 nm) for improvement of the morphology of layers. Atomic force microscopy (AFM) measurement showed that the morphology of the layers depends on the type of laser irradiations and solvent bath.