Two color emission from PPV-PTV copolymer and Alq3 hetero-sturcture EL device

An alternating copolymer of PPV and PTV, poly[2-methoxy-5-(3,7-dimethyl)octyloxy-1,4-phenylenevinylene-alt-2,5thienylenevinylene] (DAPPV-PTV) has been synthesized. Single layer EL device using DAPPV-PTV as an emitting layer between ITO and Al electrodes has been fabricated, and the light emission becomes visible at 3 V. The EL emission maximum of the device is about 620 nm. Double layer EL device using DAPPV-PTV and Alq3 has also been fabricated. The double layer EL device shows two-color emission depending on the applied voltage. The device emits a pale green color from 8 V, and then the color turns to red at about 18 V.