Photoluminescence properties of copolymers with iridium-complex Ir(thq)₂(dbm) units in the fluorene main chain

Copolyfluorenes with various concentrations (2, 4, 8, 12, 16, and 20 %) of red-light emitting Ir(III)-complex Ir(thq)₂(dbm) units on the main chain are synthesized and the photoluminescence is investigated at 298-12 K. The intensity of the emission at about 620 nm increases with increasing the Ir-complex concentration from 2 % to 4 % but decreases with increasing the concentration from 4 % by the concentration quenching, while the blue emission from polyfluorene also decreases by energy transfer to Ircomplex. The two emission intensities increase with decreasing temperature from 298 K to 12 K. The red emission shows a red shift with increasing the concentration, by the solid state solvation effect.