Embedding red-emitting dyes in robust hydrogen-bonded organic framework for application in warm white light-emitting diodes

Abstract

Broadband yellow-emitting phosphors are very attractive for warm white light-emitting diodes (WLEDs) used in solid-state lighting, backlight display, and related fields. In this work, we describe a room temperature, solution processable yellow-emitting phosphors for warm WLEDs using the chemically stable nanoscale hydrogen-bonded organic framework (HOF) PFC-1 as the host. By embedding the red-emitting dyes of rhodamine B (RhB), rhodamine 6G (Rh6G), 4-( p -dimethylaminostyryl)-1-methylpyridinium (DSM), and 4-(dicyanomethylene)-2-methyl-6-( p -dimethylaminostyryl)-4H-pyran (DCM) in the green-emitting nano PFC-1, respectively, four types of single-matrix yellow-emitting nanocomposites were obtained. Due to the spectral combination of host PFC-1 and guest dyes, the obtained nanocomposites show broader emission spectra than that of the commercial yellow phosphor. Specifically, RhB@PFC-1 has a promising quantum yield of 17.8%. By coating the nanophosphors on the commercial blue LED chips (450 nm), bright sources of warm-white light were realized. It was found that the RhB@PFC-1 coated LED has an excellent color rendering index (CRI) of 85.6 and a correlated color temperature (CCT) of 4669 K at a drive current of 300 mA, while Rh6G@PFC-1 coated LED shows warm white light with a low CCT of 3100 K and a promising CRI of 75.4 K. This Dye@HOF strategy opens an avenue to developing yellow-emitting phosphors for the use in high color rendering warm WLEDs. • A series of yellow-emitting Dye@PFC-1 nanophosphors were reported. • The Dye@PFC-1 nanocomposites show a broader emission band than that of YAG:Ce 3+ . • Bright sources of warm white light were achieved by coating the nanocomposites on blue LED chips. • The WLED coated with RhB@PFC-1 exhibits a CRI of 85.6 and a CCT of 4669 K at a 300 mA driven current.