title: A Strategy to enhance Eu3+ emission from LiYF4:Eu nanophosphors and green-to-orange multicolor tunable, transparent nanophosphor-polymer composites.
abstract: LiYF4:Eu nanophosphors with a single tetragonal phase are synthesized, and various strategies to enhance the Eu(3+) emission from the nanophosphors are investigated. The optimized Eu(3+) concentration is 35 mol%, and the red emission peaks due to the (5)D0 →(7)FJ (J = 1 and 2) transitions of Eu(3+) ions are further enhanced by energy transfer from a sensitizer pair of Ce(3+) and Tb(3+). The triple doping of Ce, Tb, and Eu into the LiYF4 host more effectively enhances the Eu(3+) emission than the core/shell strategies of LiYF4:Eu(35%)/LiYF4:Ce(15%), Tb(15%) and LiYF4:Ce(15%), Tb(15%)/LiYF4:Eu(35%) architectures. Efficient energy transfer from Ce(3+) to Eu(3+) through Tb(3+) results in three times higher Eu(3+) emission intensity from LiYF4:Ce(15%), Tb(15%), Eu(1%) nanophosphors compared with LiYF4:Eu(35%), which contains the optimized Eu(3+) concentration. Owing to the energy transfer of Ce(3+) → Tb(3+) and Ce(3+) → Tb(3+) → Eu(3+), intense green and red emission peaks are observed from LiYF4:Ce(13%), Tb(14%), Eu(1-5%) (LiYF4:Ce, Tb, Eu) nanophosphors, and the intensity ratio of green to red emission is controlled by adjusting the Eu(3+) concentration. With increasing Eu(3+) concentration, the LiYF4:Ce, Tb, Eu nanophosphors exhibit multicolor emission from green to orange. In addition, the successful incorporation of LiYF4:Ce, Tb, Eu nanophosphors into polydimethylsiloxane (PDMS) facilitates the preparation of highly transparent nanophosphor-PDMS composites that present excellent multicolor tunability.
authors.affiliation: Center for Materials Architecturing, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 136-791, Republic of Korea.
authors.forename: Su Yeon
authors.initials: SY
authors.lastname: Kim
authors.affiliation: Materials Research Center, SAIT, Samsung Electronics Co., 130, Samsung-ro, Youngtong-gu, Suwon-si, Gyeonggi-do 443-803, Republic of Korea.
authors.forename: Yu-Ho
authors.initials: YH
authors.lastname: Won
authors.affiliation: Center for Materials Architecturing, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 136-791, Republic of Korea.
authors.forename: Ho Seong
authors.initials: HS
authors.lastname: Jang