DCM derivatives as dopants for polymer light-emitting diode

Abstract

A series of derivatives of 4-(Dicyanomethylene)-2-methyl-6-[p-(dimethylamino) styryl]-4H-pyran (DCM) have been synthesized by Knoevenagel condensation and they have been characterized with NMR, UV-visible and photoluminescence study. The electrolumnescent devices have been fabricated as typical single-layer devices consisting of ITO/polymer film/Al. The polymer films consist of a host polymer, poly(N-vinylcarbazole) which transport holes, a electron transporting material, 2-(4-biphenylyl)-5-(4-tert-butylphenyl) 1,3,4- oxadiazole (PBD), and the dopants, DCM derivatives. The device in which the concentration of dopant, (2,6-Bis{2-[4-(dibutylamino)phenyl]vinyl}-4H-pyran-4-ylidene)methane-1,1-dicarbonitrile (DCM2NBu), is 5 wt%, shows the pure red emission with the CIE coordinate, (0.66, 0.33), and the maximum emissive wavelength, 643 nm. The turn-on voltage of the device is $1.4×10^{8} V/m$.