Hye Yong Chu

We have prepared and evaluated two liquid prepolymers and their UV-cured films for flexible display applications. 2,3,5,6,2′,3′,5′,6′-Octafluoro-4,4′-bis-[2-(2-{2-[2-(2,3,5,6-tetrafluoro-4-vinyl-phenoxy)-ethoxy]-ethoxy}-ethoxy)-ethoxy]-biphenyl (7) and 2,3,5,6,2′,3′,5′,6′-octafluoro-4,4′-bis-[2-(2-{2-[1,1-difluoro-2-(2,3,5,6-tetrafluoro-4-vinyl-phenoxy)-ethoxy]-1,1,2,2-tetrafluoro-ethoxy}-1,1,2,2-tetrafluoro-ethoxy)-2,2-difluoro-ethoxy]-biphenyl (8) are synthesized with decafluorobiphenyl, 2,3,4,5,6-pentafluorostyrene, and tetraethylene glycol or fluorinated tetraethylene glycol. The UV-cured films prepared from these prepolymers show mechanical flexibility and optical transparency. The refractive indices and optical losses of the films prepared from prepolymers 7 and 8 are around 1.51 and 1.43, and 1.03 and 1.06 dB cm⁻¹ at a wavelength of 633 nm. The films are thermostable at high temperature over 350 °C. The ultimate stress, initial modulus, and elongation of the films prepared from prepolymers 7 and 8 are 15.5 MPa, 0.42 GPa, and 12.2%, and 13.8 MPa, 0.49 GPa, and 6.8%, respectively. Finally, we have demonstrated a flexible waveguide display film fabricated from our prepolymers and identified the liquid prepolymers as possible good candidate materials for flexible display applications.

We are successful to lit the organic light emitting diode (OLED) lighting panel through the magnetically coupled wireless power transmission technology. For the wireless power transmission, we used the operation frequency 932 kHz, specially designed double spiral type transmitter, small and thin receiver on the four layered printed circuit board, and schottky diodes for the full bridge rectifier. Our white OLED is a hybrid type, in which phosphorescent and fluorescent organics are used together to generate stable white color. The total efficiency of power transmission is around 72%.