Supporting Information

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Supporting Information

Multisite-Occupancy-Driven Intense Narrow-Band Blue Emission from Sr5SiO4Cl6:Eu2+ Phosphor with Excellent Stability and Color

Performance

Somrita Duttaa_{, Sudipta Som}b,_{*, Mohan Lal Meena}b_{, Rajneesh Chaurasiya}c

and Teng-Ming Chena,_*

a_{Phosphors Research Laboratory, Department of Applied Chemistry,}

National Chiao Tung University, 1001 University Road, Hsinchu 30010, Taiwan.

b_{Department of Chemical Engineering, National Taiwan University, No. 1,}

Section 4, Roosevelt Road, Taipei 10617, Taiwan

C_{Department of Physics & Center for Solar Energy, Indian Institute of}

Technology Jodhpur, 342037, India * E-mail: [email protected]

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Fig. S1 Illustration of the crystal structure of Sr5SiO4Cl6 drawn via VESTA

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Fig. S2 Variation of lattice parameters and volume of Sr5-xEuxSiO4Cl6

phosphors with the increase in Eu2+_{concentration from x= 0 to x= 0.2.}

0

1

2

3

4

5

9.07 9.08 9.09 14.03 14.04 14.05 14.06 11.10 11.12 11.14 1377 1380 1383

b (

Å

)

a (

Å

)

Eu

2+

concentration (mol%)

c (

Å

)

V (

Å

3

)

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Fig. S3 TG- DSC curve of SSC:2 mol% Eu2+_{phosphors from room}

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Fig. S4 Electron band structure of SSC: 2 mol% Eu2+_{estimated via DFT}

for the substitution of Eu2+_{in place of (a) Sr(I), and (b) Sr(II) sites.}

-1 0 1 2 3 4 5 6     Ene rgy ( eV ) Eg () = 4.8 eV  EF -1 0 1 2 3 4 5 6     Energy (eV ) Eg () = 4.8 eV  EF

(a)

(b)

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Fig. S5 (a) Decay lifetime of Eu2+_{substituted at Sr(II) site of Sr}

5-xEuxSiO4Cl6 (x= 0.025, 0.1 and 0.2) phosphors. Decay lifetime of Eu2+

substituted at various sites of (b) Sr5-xEuxSiO4Cl6 (x= 0.025), (c) Sr 5-xEuxSiO4Cl6 (x= 0.1), and (d) Sr5-xEuxSiO4Cl6 (x= 0.2) phosphors.

200 400 600 800 1000 10 100 Decay time (ns) In tensity (a.u. ) Sr5-xEuxSiO4Cl6 x= 0.025 x= 0.1 x= 0.2

Eu2+_{substituted at Sr(II) site}

emi= 406 nm;exc= 360 nm 0 5000 10000 15000 20000 0.01 0.1 1 Sr(I) Sr(II) Sr(III) N o rm alized Intensity Decay time (ns) Sr5-xEuxSiO4Cl6 (x= 0.025) (a) (b) (c) (d) 0 5000 10000 15000 20000 0.01 0.1 1 Sr5-xEuxSiO4Cl6 (x= 0.1) Sr(I) Sr(II) Sr(III) Norm ali ze d In te n s it y Decay time (ns) 0 5000 10000 15000 20000 0.01 0.1 1 Decay time (ns) Sr5-xEuxSiO4Cl6 (x= 0.2) N o rm alize d In tens ity Sr(I) Sr(II) Sr(III)

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Fig. S6 Thermoluminescence pattern and deconvolution of TL glow curve-indicating existence of deep traps promoting thermal stability of the present phosphors

50

100

150

200

250

300

350

400

In

tensity

(a.u.

)

Temperature (°C)

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Fig. S7 Variation of (a) FWHM of the temperature-dependent PL emission for Sr4.9Eu0.1SiO4Cl6 phosphors ranging from 298 K to 523 K, and (b)

Stokes’ shift with the increase in Eu2+_{concentration in SSC: 2 mol% Eu2+}

phosphors. 300 350 400 450 500 550 20 25 30 35 40 45 50

FW

H

M

(

nm

)

Temperature (K)

(a)

(b)

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 3400 3600 3800 4000 4200 4400 4600 4800

Eu

2+

concentration (mol%)

S

to

ke'

s

sh

if

t

(c

m

-1

)

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Fig. S8 Variation of temperature-dependent integral PL emission intensity of Sr4.9Eu0.1SiO4Cl6 phosphors with rise in temperature ranging from 298

K to 523 K (blue curve) and corresponding reverse curve during cooling procedure in temperature range from 523 K to 298 K (red curve).

300

350

400

450

500

550

0.86

0.88

0.90

0.92

0.94

0.96

0.98

1.00 N

o

rm

alize

d

Inte

ns

ity

(a.u.)

Temperature (K)

Heating process Cooling process

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Fig. S9 Configuration coordinate diagram to clarify thermal stability and corresponding activation energy.

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Table S1. Rietveld refinement data of Sr5SiO4Cl6 host using PDXL

software

Refined Formula Sr5SiO4Cl6

Space group C 2/c (15) Lattice parameters a (Å) 9.077 b (Å) 14.049 c (Å) 11.127  =  90°  103.46° V (Å3₎ _1379.985 Rp 4.64 % Rwp 6.72 %

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Table S2. Atomic coordinates, isotropic displacements, bond lengths, and

occupancies of Sr5SiO4Cl6 by using PDXL software

Atom x y z Biso Occ.

Sr1 0.1536 0.0781 0.1333 0.007501 1 Sr2 0.5545 0.1273 0.9796 0.008298 1 Sr3 0 0.7986 0.25 0.008796 1 Si 0 0.4228 0.75 0.005398 1 O1 0.3783 0.1432 0.2838 0.007601 1 O2 0.4212 0.0198 0.1326 0.007601 1 Cl1 0.25 0.25 0 0.009199 1 Cl2 0 0.2415 0.25 0.009199 1 Cl3 0.369 0.3506 0.4506 0.009802 1 Cl4 0.3252 0.4708 0.1337 0.010199 1

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Table S3 Bond lengths of Sr5SiO4Cl6 phosphors obtained from the

refinement by using PDXL software

Site Bonds Bond lengths (Å)

Site Bonds Bond lengths (Å) Sr-I Sr-Cl 2.966 Sr-II Sr-Cl 2.963 Sr-III Sr-Cl 2.857 Sr-Cl 3.060 Sr-Cl 3.095 Sr-Cl 2.857 Sr-Cl 3.066 Sr-Cl 3.266 Sr-Cl 3.015 Sr-Cl 3.099 Sr-Cl 3.310 Sr-Cl 3.015 Sr-Cl 3.121 Sr-O 2.658 Sr-Cl 3.227 Sr-Cl 3.323 Sr-O 2.570 Sr-Cl 3.227 Sr-Cl 3.341 Sr-O 2.757 Sr-O 2.514 Sr-O 2.492 Sr-O 2.514 Sr-O 2.565

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Table S4 The atom% of each element in SSC:2% Eu2+_{phosphors via}

SEM-EDS analysis. No. Sr (%) Si (%) Eu (%) Si/(Sr+Eu) 1 9.85 2.12 0.33 1/4.801887 2 9.15 1.98 0.30 1/4.772727 3 9.62 2.05 0.31 1/4.843902 4 8.83 1.83 0.29 1/4.983607 5 9.71 2.08 0.32 1/4.822115 Average 9.432 2.012 0.31 1/4.841948

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Table S5 Badar charge analysis*

*Valance electron Eu (10), Sr (10), Cl (7), O (6) and Si (4)

Configurations Sr Si O Cl Eu

Pristine Phosphors 8.4 0.1 7.7 7.8 ---

Eu2+_{substituted in Sr(I) site} _{8.4 0.1} _7.7 _7.8 _8.48

Eu2+_{substituted in Sr(II) site} _{8.4 0.1} _7.7 _7.8 _8.45

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Table S6 Comparison of latest reported Eu2+_{doped blue-emitting}

phosphors with the present phosphor.

Phosphor λexc (nm) λemi (nm) IQY (%) Reference Sr5(PO4)3Cl:Eu2+ 395 444 84.32 1 Sr3MgSi2O8:Eu2+ 380 455 78.30 2 KMg4(PO4)3:Eu2+ 365 450 50.44 3 BAM:Eu2+ ₃₆₅ ₄₆₂ ₉₂ _{4, 5} SSC: Eu2+ ₃₆₅ ₄₅₀ _91.4 _{Present work}

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Table S7 Optical Properties of the fabricated LEDs Forward Bias Current

I (mA) CIE x CIE y CCT (K) CRI (Ra) 100 0.394 0.394 3526 94 200 0.395 0.395 3522 93 250 0.396 0.396 3523 92 300 0.393 0.402 3525 93 350 0.392 0.403 3527 94 400 0.417 0.425 3524 92 450 0.409 0.406 3528 91 References

1. J. Zheng, Q. Cheng, S. Wu, Z. Guo, Y. Zhuang, Y. Lu, Y. Li, C. Chen, J. Mater. Chem. C, 2015, 3, 11219

2. H. J. Song, D. K. Yim, H.-S. Roh, I. S. Cho, S.-J. Kim, Y.-H. Jin, H.-W. Shim, D.-W. Kim and K. S. Hong, J. Mater. Chem. C, 2013, 1, 500.

3. J. Chen, Y. Liu, L. Mei, H. Liu, M. Fang and Z. Huang, Sci. Rep., 2015, 5, 9673.

4. Denault, K. A.; Brgoch, J.; Kloß, S. D.; Gaultois, M. W.; Siewenie, J.; Page, K.; Seshadri, R. ACS Appl. Mater. Interfaces 2015, 7, 7264−7272