title: Flexible transparent displays based on core/shell upconversion nanophosphor-incorporated polymer waveguides.
abstract: Core/shell (C/S)-structured upconversion nanophosphor (UCNP)-incorporated polymer waveguide-based flexible transparent displays are demonstrated. Bright green- and blue-emitting Li(Gd,Y)F4:Yb,Er and Li(Gd,Y)F4:Yb,Tm UCNPs are synthesized via solution chemical route. Their upconversion luminescence (UCL) intensities are enhanced by the formation of C/S structure with LiYF4shell. The Li(Gd,Y)F4:Yb,Er/LiYF4and Li(Gd,Y)F4:Yb,Tm/LiYF4C/S UCNPs exhibit 3.3 and 2.0 times higher UCL intensities than core counterparts, respectively. In addition, NaGdF4:Yb,Tm/NaGdF4:Eu C/S UCNPs are synthesized and they show red emission via energy transfer and migration of Yb3+→ Tm3+→ Gd3+→ Eu3+. The C/S UCNPs are incorporated into bisphenol A ethoxylate diacrylate which is used as a core material of polymer waveguides. The fabricated stripe-type polymer waveguides are highly flexible and transparent (transmittance > 90% in spectral range of 443-900 nm). The polymer waveguides exhibit bright blue, green, and red luminescence, depending on the incorporated UCNPs into the polymer core, under coupling with a near infrared (NIR) laser. Moreover, patterned polymer waveguide-based display devices are fabricated by reactive ion etching process and they realize bright blue-, green-, and red-colored characters under coupling with an NIR laser.
authors.affiliation: Electronics and Telecommunications Research Institute (ETRI), 218 Gajeong-ro, Yuseong-gu, Daejeon 34129, Republic of Korea.
authors.forename: Bong Je
authors.initials: BJ
authors.lastname: Park
authors.affiliation: Materials Architecturing Research Center, Korea Institute of Science and Technology, 5, Hwarang-ro 14-gil, Seongbuk-gu, Seoul 02792, Republic of Korea.|Department of Chemistry, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea.
authors.forename: A-Ra
authors.initials: AR
authors.lastname: Hong
authors.affiliation: Electronics and Telecommunications Research Institute (ETRI), 218 Gajeong-ro, Yuseong-gu, Daejeon 34129, Republic of Korea.
authors.forename: Suntak
authors.initials: S
authors.lastname: Park
authors.affiliation: Electronics and Telecommunications Research Institute (ETRI), 218 Gajeong-ro, Yuseong-gu, Daejeon 34129, Republic of Korea.
authors.forename: Ki-Uk
authors.initials: KU
authors.lastname: Kyung
authors.affiliation: Department of Chemistry, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea.
authors.forename: Kwangyeol
authors.initials: K
authors.lastname: Lee
authors.affiliation: Materials Architecturing Research Center, Korea Institute of Science and Technology, 5, Hwarang-ro 14-gil, Seongbuk-gu, Seoul 02792, Republic of Korea.|Department of Nanomaterials Science and Engineering, Korea University of Science and Technology, 218 Gajeong-ro, Yuseong-gu, Daejeon 34113, Republic of Korea.
authors.forename: Ho
authors.initials: H
authors.lastname: Seong Jang