Preparation And Application Research Of Large-area Film-forming White Polymeric Phosphor Applied In Near UV-excited LED

Near ultraviolet(NUV)excited white light-emitting diodes(WLED)have undergone rapid development as an indispensable solid state light source in the next generation lighting industry and display field owing to their superior advantages such as high color rendering index,strong reduction as well as being impregnable of exciting light.Furthermore,polymeric phosphor applied in NUV-based WLED has become immediate research focus in virtue of excellent film forming,cost effective and mass preparation.Currently,phosphor converted LEDs are generally fabricated by the process of mixing with polymer material such as epoxy resin or organosilicone,which is process exhausting,costly,even poor luminous performance caused by the dilution of the luminous element.Additionally,the device with large area is hard to be fabricated.Based on this,co-polymer poly(styrene-co-glycidyl methacrylate)matrix phosphor with the ability of directly film-forming is designed and synthesized in this paper.And finally,a novel large area film forming encapsulation method is realized.the conclusions are as follows:1.A novel red emitting polymeric complex poly(styrene-co-glycidyl methacrylate)-Eu(TTA)2(Phen)(P(St-co-GMAEu))that can match with 365 nm near UV chip was synthesized using Eu(TTA)2(Phen)as the complex precursor and poly(styrene-co-glycidyl methacrylate)(P(St-co-GMA))as macromolecular ligand.The results indicate that P(St-co-GMAEu)shows a wide-band excitation with the optimum excitation wavelength at 365 nm when monitor wavelength is 612 nm.The optimum excitation wavelength is 365 nm,the best match can be achieved with 365nm near UV chip;The intensity of characteristic emission peak at 612 nm of polymer phosphor is up to 4 times higher than that of precursor complex by the reason of excellent sensitization effect of the macromolecular matrix on the luminescent center Eu3+;Fluorescence quenching of precursor complex(the concentration is 7.5 wt%)in polymer matrix can be largely delayed thanks to the diluting effects of macromolecular conformation on luminous units;The polymer phosphor has relative high quantum yield(67.04%)and longer fluorescence lifetime(0.685 ms);Performance of two kinds of devices respectively fabricated by traditional encapsulation and directly film-forming encapsulation were contrastively studied,founding that the performance of later has a significantly improvement,and the brightness reached 12120 cd/m2.2.High color rendering white emitting polymeric phosphor P(St-co-GMAEu/Tb/Zn)that can match with 365 nm near UV chip was synthesized using Eu(TTA)2(Phen),Tb(p-BBA)3,Zn(BTZ)as the r(R)/g(G)/b(B)three primary color complex precursors and P(St-co-GMA)as macromolecular ligand on the base of perfect sensitization of co-polymer matrix on luminescence center Eu3+.The white light emission of the polymeric phosphor can be realized by tuning the ratios of the trichromatic complexes or selecting appropriate excitation wavelengths.The optimal CIE coordinate is(0.332,0.337)upon excitation wavelength at 365 nm when the ratio is R:G:B = 1:10:1.White LEDs fabricated by the directly film-forming encapsulation method exhibit red,green,blue characteristic emission.The luminance efficiency is 103 1m/W,CCT is 5308 K and CRI is as high as 95.2 when the driving current is 350 mA.And the CIE coordinate of LED device is(0.35,0.34),showing minor deviation from photoluminescence.Additionally,the TG analysis indicated the polymeric phosphor remains stable up to 272.6 ℃,which completely meets the requirements of fabrication and operation temperature(180℃)for LED.3.A new luminescent pattern ’UV chip + Yellow/blue integrated phosphor’ was presented and silicate phosphor-containing composite film applied in UV chip were fabricated on the base of the blue emitting behavior of co-polymer matrix.SEM micrographs indicate that the silicate phosphor particles are embedded in co-polymer matrix separate from each other with a certain spacing and without agglomeration;The mechanism model of coupling agent in organic and inorganic blends system was established and gave a clear explanation of the promoting effect on compatibility;More importantly,mutual enhancement in blue and yellow characteristic emission intensity of two ingredients is observed.By varying the weigh percentage of silicate phosphor,yellow-to-white photoluminescent color-tuning could be readily accomplished,and the optimal CIE coordinate is(0.354,0.322).White LEDs were fabricated using prepared silicate phosphor doped composite material,showing CCT of 5917 K,CRI of 84.6.Large area white lighting device came into being When a larger size composite film was simply assembled with COB.