title: Highly circularly polarized white light using a combination of white polymer light-emitting diode and wideband cholesteric liquid crystal reflector.
abstract: We present a simple and intriguing device that generates highly circularly polarized white light. It comprises white polymer light-emitting diodes (WPLEDs) attached to a wideband cholesteric liquid crystal (CLC) reflector with a wide photonic bandgap (PBG) covering the visible range. The degree of circular polarization realized is very high over the visible range. The wide PBG was realized by introducing a gradient in pitch of the cholesteric helix by controlling the twisting power within the CLC medium. WPLEDs fabricated using a ternary (red, green, and blue) fluorescent polymer blend with the same moiety showed a low turn-on voltage, high brightness, high efficiency, and good color stability.
authors.affiliation: School of Mechanical and Advanced Materials Engineering/Low Dimensional Carbon Materials Center, Ulsan National Institute of Science and Technology, UNIST-gil 50, Ulsan 689-805, South Korea.
authors.forename: Hyun-Jung
authors.initials: HJ
authors.lastname: Lee
authors.forename: Bo Ram
authors.initials: BR
authors.lastname: Lee
authors.forename: Suk-Won
authors.initials: SW
authors.lastname: Choi
authors.forename: Myoung Hoon
authors.initials: MH
authors.lastname: Song