Flexible transparent displays based on core/shell upconversion nanophosphor-incorporated polymer waveguides

Area of Science:

• Materials Science
• Nanotechnology
• Optoelectronics

Background:

• Upconversion nanophosphors (UCNPs) offer potential for advanced optical applications.
• Developing efficient and stable UCNPs for display technologies remains a challenge.
• Polymer waveguides provide a flexible and transparent platform for optoelectronic devices.

Purpose of the Study:

• To demonstrate flexible transparent displays based on core/shell (C/S) UCNP-incorporated polymer waveguides.
• To enhance the upconversion luminescence (UCL) intensity of UCNPs through C/S nanostructure formation.
• To realize full-color emission (blue, green, red) in polymer waveguide displays.

Main Methods:

• Synthesis of core/shell UCNPs (Li(Gd,Y)F4:Yb,Er/LiYF4, Li(Gd,Y)F4:Yb,Tm/LiYF4, NaGdF4:Yb,Tm/NaGdF4:Eu) via solution chemical routes.
• Incorporation of C/S UCNPs into a bisphenol A ethoxylate diacrylate polymer waveguide core.
• Fabrication of stripe-type and patterned polymer waveguide displays using reactive ion etching.

Main Results:

• C/S UCNPs exhibited significantly enhanced UCL intensities (3.3x for green, 2.0x for blue) compared to their core counterparts.
• Synthesized C/S UCNPs demonstrated bright blue, green, and red emissions under near-infrared (NIR) laser excitation.
• Fabricated polymer waveguide displays showed high transparency (>90%) and flexibility, displaying bright colored characters.

Conclusions:

• Core/shell nanostructuring effectively enhances UCNP luminescence for display applications.
• Polymer waveguide technology integrated with C/S UCNPs enables flexible, transparent, and full-color displays.
• This approach presents a promising pathway for developing next-generation optoelectronic devices.