Polymer Light-Emitting Diodes Fabricated Using Poly(9,9-dioctylfuorene) Gel by Thermal Printing Method

The optical characteristics of poly(9,9-dioctylfluorene) (F8) gel and polymer light-emitting diodes (PLEDs) fabricated using F8 gel by the thermal printing method were investigated. F8 gel was formed when the F8 content was more than a certain concentration in 1,2,4-trichlorobenzen with a high boiling temperature. F8 gel was transformed into F8 sol by annealing the F8 gel at approximately more than the glass transition temperature of F8. The transition between the F8 sol and gel was reversible. The occurrence of the β phase results in the formation of F8 gel. For this thermal printing method, the optical properties of F8 films and PLEDs can be controlled by the transfer speed of F8 gel, and the annealing substrate temperature. Blue, yellow-green, and red lights were emitted from the PLEDs using F8 gel, that doped with a yellow-green emissive fluorene copolymer, and that doped with a red emissive phosphor, respectively. We demonstrated the possibility of the polarized PLEDs using conducting polymer gels doped with emissive dopants by the thermal printing method.