Color Tunable Donor-Acceptor Electroluminescent Copolymers: Synthesis, Characterization, Photophysical Properties and PLED Fabrication

摘要

A series of novel color tunable donor-acceptor conjugated copolymers (CPs) are developed from N-octylcarbazole (Cz-O) and N-phenyl-1,8-naphthalimide (N-PN) with a combination of feed ratios of Cz-O and N-PN (50:50, 65:35, 75:25, 90:10, 95:05 and 99:01). The copolymers exhibit desirable solubility in organic solvents like chlorobenzene, chloroform, THF, etc., color tunability from blue to orange and desired electrochemical properties and are utilized for PLED fabrication. The new CPs are well characterized using NMR, FT-IR, TGA, DSC, UV-Vis and PL spectroscopy and their structural and photophysical properties are well correlated. The PL emissions of the CPs are red shifted steadily with increase in the N-PN content in the CP main chains. PLEDs are fabricated using these newly developed CPs as emissive layer (EML) in ITO/PEDOT:PSS/PCzN-PN/BCP/LiF/ Al configuration. Among all devices, PLEDs using PCzN-PN05 copolymer as EML is found to give the best device performance with maximum brightness of 309 cd m~(-2) and 0.451 cd A~(-1) luminous efficiency.