2017 Volume 30 Issue 4 Pages 437-443
Invisible near-infrared (NIR) to visible (VIS) upconversion (UC) emission of rare-earth doped ceramics is receiving much attention for transparent display applications. In this study, a new dual-wavelength (DW) NIR excitation scheme for the VIS-UC emission of Er3+ doped NaYF4 (NaYF4:Er3+) was proposed to achieve a high green color purity and was applied to non-projection-type transparent displays. For the optimization of green color purity, various rare-earth ions (RE3+) were co-doped into NaYF4:Er3+ (NaYF4:Er3+, RE3+). Among those, NaYF4 co-doped with Er3+ and Ce3+ (NaYF4:Er3+, Ce3+) showed the highest green color purity under DW-NIR excitation. Furthermore, the excitation wavelengths of DW-UC were also investigated. Moreover, a NaYF4:Er3+, Ce3+ embedded transparent and flexible polymer composite was prepared, which emitted a strong "point emission" at the cross point of the DW-NIR excitation lights that were introduced from the side surface of the composite sheet. Therefore, the obtained polymer/NaYF4:Er3+, Ce3+ composite is an attractive candidate material for non-projection-type transparent and flexible displays.