Supporting Information

Commercial approach for fabrication of bulk and nano phosphors converted

into highly-efficient white LEDs

Jaya Dwivedia,b, Pawan Kumara,b, Arun Kumara,b , Sudamac,b, V.N. Singhd,b, Bhanu Pratap Singh e,b, S.K. Dhawanf,b, V. Shankera,b and Bipin Kumar Guptaa,b,*

a Luminescent Materials and Devices Group, Materials Physics and Engineering Division bCSIR - National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi, India

cOptical Radiation Standards, Apex Level Standards & Industrial Metrologyd Electron and Ion Microscopy Section, Sophisticated Analytical Instruments Division

ePhysics and Engineering of Carbon, Materials Physics and Engineering DivisionfPolymeric and Soft Materials, Materials Physics and Engineering Division

Scheme 1: Flow chart of Synthesis of Y2.85Al 5O12Ce3+0.15 (bulk and nano) phosphors.

Electronic Supplementary Material (ESI) for RSC Advances.This journal is © The Royal Society of Chemistry 2014

Fig. S1 : Chemical structural formula of epoxy resins and curing agent (triethylene tetra

amine).The most common and important class of epoxy resins is formed from reacting

epichlorohydrin with bisphenol A to form diglycidyl ethers of bisphenol A. The simplest resin of

this class is formed from reacting two moles of epichlorohydrin with one mole of bisphenol A to

form the bisphenol A diglycidyl ether (commonly abbreviated to DGEBA or BADGE). DGEBA

resins are transparent colourless-to-pale-yellow liquids at room temperature, with viscosity

typically in the range of 5-15 Pa.s at 25°C. Industrial grades normally contain some distribution

of molecular weight, since pure DGEBA shows a strong tendency to form a crystalline solid

upon storage at ambient temperature.

Protocol for Fabrication of white LEDs

The fabrication protocol is described in following steps:

Step I: Initially, YAG: Ce powder (bulk 500 mg and nano 10 mg ) were dispersed in Epoxy solution in 100:12.5 ratio by volume

Step II: Above mixture is mixed properly to make it homogeneous and then, dispensed in empty space available on commercial purchase blue LED strips till it is filled properly.

Step III: Dry it at room temperature for few hrs.

Step IV: Finally, for the testing purpose, we connected the phosphor coated blue LED strips with 12 volt DC power supply which is required for electroluminescence of commercial blue LED.

All steps for Fabrication of white LEDs are summarized in following schematic diagram

Scheme 2: Flow chart for fabrication of white LEDs to explore feasibility of synthesized bulk and nano phosphors in display strips.

Moving from left to right, the first Figure shows commercially purchased blue LED strip. The

second Figure shows an isolated blue LED in off condition. A hemispherical groove in blue LED

can be clearly seen in this Figure The third Figure shows the same blue LED after filling the

empty groove with bulk YAG:Ce. Fourth Figure shows a blue LED filled with nano YAG:Ce.

The fifth Figure shows a glowing phosphor converted blue LED strip emitting white light. We

focused on second approach for dispensing epoxy resin with phosphor in InGaN blue LEDs.

Figure S2 : Color temperature and CIE color coordinates measurement set-up (Colorimeter,

C1210, serial no. 1296104) (facility at NPL, New Delhi, India).

Fig. S3 : Luminance measurement L1000 measurement set-up (facility at NPL, New Delhi,

India).

Fig. S4:. X-ray diffraction patterns of Y(3- x)Al 5O12:Ce3+x (x = 0.03- 0.3).

Table TS1:

Least squares refined unit cell parameters and cell volume for variants of Y3-xAl5O12:Cex

nanophosphor in the range x = 0.03–0.30.

The lattice parameters were calculated from the observed d values through a least square fitting

method using computer program based ‘unit cell refinement software’. It can be noticed that the

cell parameters and cell volume are increasing as the concentration of Ce increses up to x=0.15

and decreasing there after. Such characteristic has been previously obsrerved for other rare-earth

oxides sytem in our earlier publication.30

Y3-xAl5O12:Cex (x=0.03 to 0.3) Lattice parameter a=b=c(Å)

Cell Volume (Å)3

JCPDS Standard Card No. 33-0040 12.00890

Y2.97Al5O12Ce0.033+ 12.01980.0027 1736.5677

Y2.94Al5O12Ce0.063+ 12.02030.0011 1736.7844

Y2.91Al5O12Ce0.093+ 12.02090.0034 1737.0445

Y2.88Al5O12Ce0.123+ 12.02110.0013 1737.1312

Y2.85Al5O12Ce0.153+ 12.02180.0017 1737.4347

Y2.82Al5O12Ce0.183+ 12.02060.0028 1736.9144

Y2.79Al5O12Ce0.213+ 12.02010.0022 1736.6977

Y2.76Al5O12Ce0.243+ 12.01930.0015 1736.3510

Y2.73Al5O12Ce0.273+ 12.01820.0031 1735.8743

Y2.70Al5O12Ce0.303+ 12.01750.0025 1735.5710

Fig. S5 : Represents Raman spectra of YAG:Ce bulk phosphor.

Fig. S6 : Represents Raman spectra of YAG:Ce nano phosphor.

Fig. S7 : Represents FTIR of YAG:Ce bulk phosphor.

Fig. S8 : Represents FTIR of YAG:Ce nano phosphor.

Fig. S9 : Represents elemental analysis by XPS survey scan.

Fig. S10: PL emission spectra at 468 nm excitation wavelength for optimizing the concentration of Y2.85Al 5O12Ce3+

0.15 bulk phosphors at 1400ºC for 4hrs.

Fig. S11: PL emission Intensity (468 nm excitation wavelength) at various temperatures for optimization of growth for Y2.85Al 5O12Ce3+

0.15 bulk phosphors for 4hrs .

Fig. S12: XRD patterns of YAG:Ce prepared by auto-combustion-solid-state reaction at 1500

degree centigrade for 4 hours at optimum concentration of 5 mol %. This XRD pattern clearly

depicts the formation of other secondary phases at 1500 degree centigrade. The YAP and YAM

phases were index by JCPDS Card. No. 33-0041and 34-0368 respectively.

Fig. S13 : Photo bleaching spectra of Y2.85Al 5O12Ce3+0.15 bulk phosphors.

Fig. S14: Photo bleaching spectra of Y2.85Al 5O12Ce3+0.15 nano phosphors .

Fig. S15: Optimization of instrument before PL measurements of LED strips at 12 volt DC.