Synthesis and characterization of poly(1,4-phenylenevinylene-alt-2,5-thienylenevinylene) derivatives for organic light-emitting diodes

A new series of alternating copolymers composed of 1,4-phenylenevinylene and 2,5-thienylenylvinylene repeating units with various side chain substituents were synthesized via the Heck coupling reaction for use in light-emitting diodes (LEDs). The resulting copolymers were characterized using 1H- and 13C-NMR, DSC, and TGA. These polymers were found to be soluble in common organic solvents and are easily spin-coated onto glass substrates, producing high optical quality thin films without defects. The electro-optical properties of ITO/PEDOT/Polymer/Al devices were investigated using UV–VIS, PL and EL spectroscopy. The turn-on voltages of these devices were found to be in the range 4–16 V, with a maximum brightness of about 2900 cd/m2 at 12 V.