Near-Infrared-Light emitting diode driven white light Emission: Upconversion nanoparticles decorated Metal-Organic Frame-works thin film

The existing white light-emitting diodes (WLEDs) are mostly fabricated with downshifting phosphors and ultraviolet (UV) or blue light LED chips. To achieve unconventional upconversion white-light-emitting phosphors, a novel strategy by encapsulating upconversion nanoparticles and organic dyes into metal–organic frameworks (MOFs) at room temperature is put forward. Herein, lanthanide-doped upconversion nanoparticles (NaYF 4 :Yb,Tm@NaYF 4 core–shell UCNPs), dye 4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran (DCM) and dye Coumarin 6 (C6) with blue, red and green light emission, respectively, are encapsulated together into ZIF-8 through a facile one-pot solid-confinement conversion process. Owing to their appropriate spectral overlaps and efficient energy transfer processes between two pairs of UCNPs/DCM and UCNPs/C6 within ZIF-8, the optimized UCNP/DCM/C6@ZIF-8 thin film exhibits high-quality white-light emission upon a commercial 980 nm LED chip with ideal CIE coordinates of (0.33, 0.33), high color rendering index (CRI) value of 93 and moderate correlated color temperature (CCT) value of 5567 K. This strategy paves the way for other upconversion phosphorous nanoparticles and fluorescent molecules for WLEDs applications excited by near infrared light.