Up-Conversion of Infrared Spectrum to Visible Spectrum with NaYF₄:Yb³⁺/Er³⁺ Coated Film for Façade Envelope

Excessive heat build-up in buildings is undesirable and excess infrared (IR) radiation can be attenuated via up-conversion (UC) of IR to visible light. Sodium Yttrium Fluoride co-doped with Ytterbium and Erbium hexagonal micro-prism phosphors were synthesized for the up-conversion of IR to visible wavelengths. These synthesized UC phosphors were uniformly dispersed into an epoxy matrix for application on a transparent laminated film substrate via the Doctor Blade method. This UC phosphor coating reduced thermal irradiance and consequently a much lower interior temperature was achieved compared to a structure envelope without the coated film.