The optical behavior of multi-emission quantum dots based on Tb-doped ZnS developed via solvothermal route for bioimaging applications

Journal Pre-proof The optical behavior of multi-emission quantum dots based on Tb-doped ZnS developed via solvothermal route Salim M. El-Hamidy

PII:

S0030-4026(19)31766-8

DOI:

https://doi.org/10.1016/j.ijleo.2019.163868

Reference:

IJLEO 163868

To appear in:

Optik

Received Date:

12 September 2019

Accepted Date:

22 November 2019

Please cite this article as: El-Hamidy SM, The optical behavior of multi-emission quantum dots based on Tb-doped ZnS developed via solvothermal route, Optik (2019), doi: https://doi.org/10.1016/j.ijleo.2019.163868

This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2019 Published by Elsevier.

The optical behavior of multi-emission quantum dots based on Tbdoped ZnS developed via solvothermal route Salim M. El-Hamidya, b a

Biological Sciences Department, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia b

Pricess Dr Najla Bint Saud Al Saud center for Excellence Research in Biotechnology, King

ro

Corresponding author: [email protected]

of

Abdulaziz University, Jeddah, Saudi Arabia

-p

Abstract

Quantum dots (QDs), semiconducting nanocrystals with exceptional photophysical characteristics, have become one of the prevailing class of multifunctional

re

nanodevices and imaging probes. The engineering of QD probes became an essential step for successful clinical applications in real-life. In this work, a water soluble and highly

lP

luminescent semiconducting QDs are developed via solvothermal route. Terbium was used as a dopant to replace the Zn in the ZnS nanocrystals. Various concentrations of Tb, from 0 to 6 at.%, was doped into the ZnS. The influence of Tb dopant on the crystal

ur na

structure of the ZnS and diameter of the formed nanocrystals was investigated using Xray diffraction and transmission electron microscopy. The optical properties were studied using the UV-Vis spectrophotometer, which showed a red shift of the optical band gap. The luminescence properties showed that the doping of ZnS with 6at.% of Tb ions resulted in a remarkable enhancement of the luminescence intensity and the quantum

Jo

yield. This sample showed three distinctive light emissions (blue, green and red) when excited at 320 nm, 360 nm and 390 nm. The obtained results embarked that the developed QDs may be employed as efficient bio-imaging probe for practical clinical applications in real-life, which is confirmed in this article for the first time. ------------------------------------------------------------------------------Keywords: Qauntum dots; ZnS; Luminscence; Structure; Bioimaging

1

1. Introduction The development of structures and materials with dimensions range from 1 to 100 nm has a fabulous influence on the encroachment of an inclusive range of fields

of

comprising medicine, energy, photonics, and catalysis [1-5]. Consequently, attentiveness in nanotechnology has enlarged intensely during the last few years [6-9]. The excitation

ro

of semiconducting nanocrystals results in the emission of narrow and tunable fluorescent light [10, 11]. These nanostructures have been produced with different configurations

-p

shapes, and sizes, which gives rise to unique physical, electronic and optical properties

re

[12-16]. The quantum dots, QDs, are sort of semiconducting nanocrystals regularly consist of 100 to 1000 atoms of the elements of II-VI group [17-20] or elements of III-V

lP

group [21-25]. Among them, semiconductor ZnS QDs showed a rapid and significant progress in research from the fundamental sciences and technologies [26-30]. The doping

ur na

of semiconducting nanocrystals is an effective and vital strategy to improve the structure, morphology, optical, luminescence, photocatalytic, and magnetic characteristics [31-35], thereby encompassing their application potential to numerous fields [36–40]. Particularly, the doping of ZnS with rare earth elements modulates the optical band gap [41, 42],

Jo

thereby it considered as promising candidate for display and lighting compounds [43, 44], where it act as efficient luminescence centers [45, 46]. In this work, a water soluble and highly luminescent semiconducting QDs are developed via solvothermal route. Terbium was used as a dopant to replace the Zn in the ZnS nanocrystals. Various concentrations of Tb, from 0 to 6 at.%, was doped into the ZnS. The influence of Tb dopant on the

2

structural phase, morphological shape, optical and luminescence features of the ZnS QDs was investigated. The Tb ions showed a remarkable enhancement of the optical and luminescence characteristics of the ZnS QDs. The obtained results embarked that the developed QDs may be employed as efficient bio-imaging probe for practical clinical applications in real-life, which is confirmed in this article for the first time.

of

2. Experimental

ro

A solvothermal method was employed to prepare Terbium-doped ZnS QDs. An aqueous solution of zinc nitrate (100 mM) and the required amount of terbium nitrate (0,

-p

2, 4 and 6 at.%) dissolvedin 40 mL of ethanol and stirring for 15 min. Another solution made of sodium sulfide (100 mM) and polyvinylpyrrolidone (50 mM) in 10 mL of

re

ethanol add drop-wise over the Tb/Zn solution. This solution transfers to a Teflon

lP

autoclave and sealed and followed by the insertion in oven at 200°C for 2h. After the complete of reaction, the resulted powders were dried at 70°C for 12h.

ur na

The phase structures were determined using X-ray diffraction (Seifert-3003XRD). The morphologies and size are inspected using transmission electron microscopy (Tecnai-12-TEM). The optical properties were evaluated using a Cary-5000-UV–Vis

Jo

spectrophotometer. The luminescence is analyzed using Perkin-Elmer-L55-spectroscopy. 3. Results and discussion 3.1 XRD analysis The crystal structures of the Tb-doped ZnS QDs were analyzed using XRD and the diffraction patterns presented in Fig.1a. All diffractions of specimens are identified to

3

the cubic ZnS structure [47-50]. The inclusion of Tb dopant results in a shift of the (111) peak to low angles with the increase of Tb contents. This significant shift of the (111) peak is implying to the change of ZnS lattice parameters [51-53]. The lattice constant is determined using the relation [54-58]. 1 𝜆 (ℎ2 + ℎ𝑘 + 𝑘 2 )2 ] 2 𝑠𝑖𝑛𝜃

(1)

of

𝑎= [

Fig 1b reveals that the inclusion of Tb dopant results in an increase of ZnS lattice

ro

constant. The increasing of the lattice constant means an increase of the crystallites size

-p

will be happened [61, 62]. The average crystallite size of the Tb-doped ZnS is evaluated according to the Debye–Scherrer formula [63-65]. The estimated mean crystallite size

re

increases because of the increasing of amount Tb ions included in the ZnS as depicted in

3.2 TEM analysis

lP

Fig. 1b.

ur na

Figure 2 displays the TEM images of Tb-doped ZnS QDs. These images reveal the spherical and monodisperse of the as-prepared Tb-doped ZnS QDs. There is no any sort of aggregations or agglomerations for the prepared nanoparticles. Nevertheless, the mean diameters are increased with increased Tb-dopant contents from 2 nm to 5.7 nm.

Jo

Furthermore, the Tb dopant causes an increase of the d-space parameter, which estimated from the fringes separation distances of the HRTEM images presented inset of Fig. 2. Therefore, the increase of sizes and lattice parameter are in agreement with that obtained from the XRD.

4

3.3 Optical studies Figure 3a shows the absorption spectra of the undoped and Tb-doped ZnS QDs. The shoulder band appeared confirms the size quantum confinement effect [66-70]. Moreover, the absorption spectra tend to shift toward long wavelength due to the increase

of

of Tb content. This shift means the decreasing of the band gap occurs [71-75]. To

ro

confirm that the optical band gap is calculated for all samples using Tauc’s relation [7678] (𝛼ℎ𝜈)2 = 𝐴 (ℎ𝜈 − 𝐸𝑔 )

-p

(2)

re

Figure 3b indicates the decreasing of ZnS band gap from 3.46 eV to 3.25 eV upon the

lP

increase of Tb contents. 3.4 Luminescence characteristics

ur na

Figure 4 displays the photoluminescence, PL, spectrum of un-doped and Tbdoped ZnS QDs. The un-doped ZnS QDs spectrum shows a very broad spectral curve with very low PL intensity. As the amount of Tb doped ZnS QDs increases the width of the PL peaks decreases and became sharp and the PL increases rapidly. On the other

Jo

hand, these spectral peaks shifted to the longer wavelength, which may argue to the monodispersion and very small size of the prepared nanocrystals [79-81]. An increase of the PL intensity was reached to five times compare with the undoped ZnS QDs as shown in Fig. 5a. The quantum yield is estimated due to the relation [82-85] ƾ𝑦 = ƾ𝑠

ƻ ǥ𝑠 Ȥ2 ƻ𝑠 ǥ Ȥ2𝑠

(3)

5

where ƻ and

ǥ are the area under the luminescent and absorptions peaks,

respectively. Ȥ is the refractive index. Figure 5b shows that the quantum yield is improved from 23% to 82% upon the increasing of Tb contents, thereby the Tb acts like active centers in the phase structure of ZnS QDs [86-90]. These unique features of the developed QDs may enable them to be served for bio-imaging probe for practical clinical

of

applications in real-life. To confirm that, the 6 at% Tb-doped ZnS QDs was used as an imaging probe for labeling the caveolin-1 protein in the lung cancer as shown in Fig. 6b.

ro

A high contrast was observed while the details of the cells are clearly observed after the developed QDs bind with these cells in comparison with the image stained with organic

-p

dye (Fig.6a). The mechanism of charge transfer due to the multi-emission colors

re

appeared due to the binding of the developed QDs with the cells is presented in Fig. 7a. The excitation of the Tb-doped ZnS QDs with wavelength of 380 nm gives rise to the

lP

transfering of electrons to the ZnS conduction bands [91-93]. These electrons transfer to the levels of the Tb ions. The Tb ions exhibit three emission peaks at 442, 490 and 531

ur na

nm, which ascribed to electronic transitions from 5D4→7F4, 5D4 →7F5 and 5D4 →7F6, respectively [94-97] as shown in Fig. 7b. 4. Conclusions

A nanocrystalline Tb-doped ZnS QDs have been developed using solvothermal

Jo

route. All samples exhibited zinc blende phase structure. Both of the lattice constants and crystallite sizes are increased upon the increase of Tb content. The TEM revealed the monodispersion of the produced nanocrystals. The absorption spectra showed a shift toward long wavelength and thereby a decrease of the optical band gap. The luminescence spectra get narrow and sharp emission peaks with high intensities

6

exceeding five times than undoped ZnS QDs. The developed QDs were employed as a bio-imaging probe for practical clinical applications in real-life. The 6 at% Tb-doped ZnS QDs exhibited an efficient imaging probe for labeling of caveolin-1 protein in the lung cancer. A high contrast was observed while the details of the cells are clearly observed after the developed QDs bind with these cells. The Tb ions exhibit three emission peaks at 442, 490 and 531 nm when binds with these cells, which ascribed to electronic

of

transitions from 5D4→7F4, 5D4 →7F5 and 5D4 →7F6, respectively. These remarkable

ro

properties suggest that the doping of ZnS QDs with Tb ions may be used as a promising candidate for luminescent and bio-imaging probe applications.

-p

References

re

[1] H.A. Al-Khanbashi, W. Shirbeeny, A.A. Al-Ghamdi, et al., Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 118 (2014) 800-805

lP

[2] A.M. Al-Amri, S.J. Yaghmour, W.E. Mahmoud, J. Cryst. Growth 334(1) (2011) 7679

[3] K. Ali, W.E. Mahmoud, Synthetic Metals 175 (2013) 52-55

ur na

[4] W.E. Mahmoud, S.J. Yaghmour, J. Luminescence 132(9) (2012) 2447-2451 [5] W.E. Mahmoud, A.M. Al-Amri, S.J. Yaghmour, Optical Materials 34(7) (2012) 10821086

[6] W.E. Mahmoud, A.A. Al-Ghamdi, F.A. Al-Agel, et al., J. Alloys Compounds 640 (2015) 122-127

Jo

[7] W.E. Mahmoud, Solar Energy Materials and Solar Cells 152 (2016) 65-72 [8] F.A. Al-Agel, W.E. Mahmoud, Sens. Actuators, B: Chem. 183 (2013) 441-445 [9] W.E. Mahmoud, A.A. Al-Ghamdi, M.W. Kadi, Radiation Physics and Chemistry 81(6) (2012) 693-696 [10] A. Fahami, F.S. Al-Hazmi, A.A. Al-Ghamdi, W.E. Mahmoud, G.W. Beall, J. Alloys Compounds 683 (2016) 100-107

7

[11] N.V. Kuchkina, E.Y. Yuzik-Klimova, S.A. Sorokina, et al., Macromolecules 46(15) (2013) 5890-5898 [12] W.E. Mahmoud, F.S. Al-Hazmi, A.A. Al-Ghamdi, et al., Superlattices and Microstructures 96 (2016) 174-178 [13] W.E. Mahmoud, Sensors and Actuators, B: Chemical 164(1) (2012) 76-81 [14] R. Easterday, C. Leonard, O. Sanchez-Felix, et al., ACS Appl. Mater. Interf. 6(23) (2014) 21652-21660

of

[15] W.E. Mahmoud, Materials Letters 177 (2016) 42-45 [16] W.E. Mahmoud, F.S. Al-Hazmi, A.A. Al-Ghamdi, et al., Synthetic Metals 217 (2016) 152-155

ro

[17] S.H. Gage, B.D. Stein, L.Z. Nikoshvili, et al., Langmuir 29(1) (2013) 466-473

[18] W.E. Mahmoud, A.A. Al-Ghamdi, F.A. Al-Agel, et al., Materials Research Bulletin

-p

72(8352) (2015) 154-159

[19] F.S. Al-Hazmi, G.W. Beall, A.A. Al-Ghamdi, et al., J. Molecular Structure 1118

re

(2016) 275-278

[20] F.A. Al-Agel, E. Al-Arfaj, A.A. Al-Ghamdi, et al., Ceramics International 41(1)

lP

(2015) 1115-1119

[21] F.S. Al-Hazmi, W.E. Mahmoud, J. Europ. Ceram. Society 34(12) (2014) 3047-3050 [22] E.Yu. Yuzik-Klimova, N.V. Kuchkina, S.A. Sorokina, et al., RSC Adv. 4(44) (2014)

ur na

23271-23280

[23] W.E. Mahmoud, A.A. Al-Ghamdi, F.A. Al-Agel, et al., Ceramics International 41(7) (2015) 9101-9106

[24] F.A. Al-Agel, E. Al-Arfaj, A.A. Al-Ghamdi, et al., J. Magn. Magn. Mater. 360 (2014) 73-79

Jo

[25] H.S. Al-Ghamdi, W.E. Mahmoud, Materials Letters 105 (2013) 62-64 [26] W.E. Mahmoud, F. Al-Hazmi, F. Al-Noaiser, Superlattices and Microstructures 68 (2014) 1-5

[27] W.E. Mahmoud, A.A. Al-Ghamdi, R.K. Gupta, et al., Superlattices and Microstructures 63 (2013) 162-167 [28] W.E. Mahmoud, Y.C. Chang, A.A. Al-Ghamdi, et al., Organic Electronics: physics, materials, applications 14(11) (2013) 2762-2769 8

[29] K.L. Mathews, A.M. Budgin, S. Beeram, et al., J. Mater. Chem. A 1(4) (2013) 11081116 [30] W.E. Mahmoud, Sensors and Actuators, B: Chemical 238 (2017) 1001-1007 [31] S.J. Yaghmour, W.E. Mahmoud, Materials Letters 109 (2013) 55-57 [32] W. Shirbeeny, M. Hafez, W.E. Mahmoud, Polym. Composites 34(4) (2013) 587-591 [33] S. Rafique, S.M. Abdullah, W.E. Mahmoud, et al., RSC Advances 6(55) (2016) 50043-50052 Colloids and Surfaces A:

Physicochemical and Engineering Aspects 485 (2015) 91-95

of

[34] F.S. Al-Hazmi, A.A. Al-Ghamdi, G.W. Beall, et al.,

[35] W.E. Mahmoud, W. Shirbeeny, A.A. Al-Ghamdi, S. Al-Heniti, J. Appl. Polym.

ro

Science 125(1) (2012) 339-343

[36] W.E. Mahmoud, F.S. Al-Hazmi, G.H. Al-Harbi, Chem. Engineering J. 281 (2015)

-p

192-198

[37] F.S. Al-Hazmi, G.H. Al-Harbi, G.W. Beall, et al., Superlattices and Microstructures

re

86 (2015) 270-274

[38] W.E. Mahmoud, A.M. Al-Sanoosi, Superlattices and Microstructures 51(4) (2012)

lP

506-511

[39] M.H.I. El Eraki, A.M.Y. El Lawindy, H.H. Hassan, et al., J. Appl. Poly. Science 103(5) (2007) 2837-2842

1605

ur na

[40] W.E. Mahmoud, A.A. Al-Ghamdi, J. Appl. Polym. Science 118(3) (2010) 1598-

[41] W.E. Mahmoud, F.A. Al-Agel, J. Phys. Chem. Solids 72(7) (2011) 904-907 [42] S.A. Al-Ghamdi, S.H. Al-Heniti, W.E. Mahmoud, Ceramics International 39(5) (2013) 5025-5030

Jo

[43] W.E. Mahmoud, T. Al-Harbi, Materials Letters 65(12) (2011) 1986-1988 [44] M. Hafez, F. Al-Marzouki, W.E. Mahmoud, Materials Letters 65(12) (2011) 18681870

[45] W.E. Mahmoud, T. Al-Harbi, J. Crystal Growth 327(1) (2011) 52-56 [46] M.H. El Eraki, A.M.Y. El Lawindy, H.H. Hassan, et al., Polym. Degrad. Stability 91(7) (2006) 1417-1423 [47] W.E. Mahmoud, A.A. Al-Ghamdi, Polym. Adv. Tech. 22(6) (2011) 877-881 9

[48] R. Al-Tuwirqi, A.A. Al-Ghamdi, N.A. Aal, et al., Superlattices and Microstructures 49(4) (2011) 416-421 [49] W.E. Mahmoud, A.A. Al-Ghamdi, Optics and Laser Technology 42(7) (2010) 11341138 [50] W.E. Mahmoud, J. Crystal Growth 312(21) (2010) 3075-3079 [51] W.E. Mahmoud, A.A. Al-Ghamdi, F. El-Tantawy, S. Al-Heniti, J. Alloys Compounds 485(1-2) (2009) 59-63

of

[52] W.E. Mahmoud, A.A. Al-Ghamdi, Polym. Composites 32(7) (2011) 1143-1147 [53] A.M.Y. El Lawindy, K.M. Abd El-Kade, W.E. Mahmoud, H.H. Hassan, Polym. International 51(7) (2002) 601-606

ro

[54] W.E. Mahmoud, A.A. Al-Ghamdi, S. Al-Heniti, S. Al-Ameer, J. Alloys Compounds 491(1-2) (2010) 742-746

-p

[55] W.E. Mahmoud, S.H. Al-Heniti, Mater. Research Bulletin 46(9) (2011) 1366-1371

Compounds 486(1-2) (2009) 9-13

re

[56] A.A. Al-Ghamdi, W.E. Mahmoud, S.J. Yaghmour, F.M. Al-Marzouki, J. Alloys

[57] W.E. Mahmoud, Europ. Polym. J. 47(8) (2011) 1534-1540

2440

lP

[58] Y.A. Kabachii, A.S. Golub, S.Y. Kochev, et al., Chem. Mater. 25(12) (2013) 2434-

[59] A.A. Al-Ghamdi, F. El-Tantawy, N. Abdel Aal, et al., Polym. Degrad. Stability

ur na

94(6) (2009) 980-986

[60] W.E. Mahmoud, A.A. Al-Ghamdi, Polym. International 59(9) (2010) 1282-1288 [61] W.E. Mahmoud, A.A. Al-Ghamdi, F. Al-Marzouki, S. Al-Ameer, J. Appl. Polym. Science 122(5) (2011) 3023-3029

[62] Y.C. Chang, W.E. Mahmoud, Comp. Phys. Communications 196 (2015) 92-112

Jo

[63] W.E. Mahmoud, A.A. Al-Ghamdi, Polym. International 61(1) (2012) 51-54 [64] F.S. Al-Hazmi, G.H. Al-Harbi, G.W. Beall, et al., Synthetic Metals 200 (2015) 5457

[65] W.E. Mahmoud, F.A. Al-Agel, E.A. Al-Arfaj, Materials Letters 96 (2013) 146-148 [66] W.E. Mahmoud, Y.C. Chang, A.A. Al-Ghamdi, F. Al-Marzouki, L.M. Bronstein, Superlattices and Microstructures 56 (2013) 86-91

10

[67] W.E. Mahmoud, S.J. Yaghmour, A.M. Al-Amri, J. Luminescence 134 (2013) 429431 [68] W.E. Mahmoud, Y.C. Chang, A.A. Al-Ghamdi, F. Al-Marzouki, L.M. Bronstein, Polym.Composites 34(2) (2013) 299-304 [69] F.A. Al-Agel, W.E. Mahmoud, J. Appl. Crystallography 45(5) (2012) 921-925 [70] F. Al-Hazmi, T. Al-Harbi, W.E. Mahmoud, Materials Letters 86 (2012) 28-30 [71] W.E. Mahmoud, A. Faidah, J. Europ. Ceramic Society 32(13) (2012) 3537-3541

of

[72] T. Al-Harbi, F. Al-Hazmi, W.E. Mahmoud, Superlattices and Microstructures 52(4) (2012) 643-647

[73] W.E. Mahmoud, S.J. Yaghmour, Optical Materials 35(3) (2013) 652-656

ro

[74] F.A. Al-Agel, W.E. Mahmoud, Materials Letters 82 (2012) 82-84

[75] W.E. Mahmoud, H.M. El-Mallah, J. Phys. D: Appl. Phys. 42(3) (2009) 035502

-p

(5pp).

[76] M. Wirey, M. Hunt, T. Blensdorf, et al., Macromol. Chem. Phys. 217(6) (2016) 794-

re

803

[77] W.E. Mahmoud, M. Hafez, N.A. El-Aal, F. El-Tantawy, Polym. International 57(1)

lP

(2008) 35-38

[78] W.E. Mahmoud, A.M.Y. El-Lawindy, M.H. El Eraki, H.H. Hassan, Sensors and Actuators, A: Physical 136(1) (2007) 229-233

ur na

[79] W.E. Mahmoud, S.A. Mansour, M. Hafez, M.A. Salam, Polym. Degrad. Stability 92(11) (2007) 2011-2015

[80] W.E. Mahmoud, M.H.I. El-Eraki, A.M.Y. El-Lawindy, H.H. Hassan, J. Physics D: Applied Physics 39(11) (2006) 2427-2432 [81] W.E. Mahmoud, T. Al-Harbi, Superlattices and Microstructures 50(1) (2011) 21-25

Jo

[82] W.E. Mahmoud, M.H.I. El-Eraki, A.M.Y. El-Lawindy, H.H. Hassan, J. Physics D: Applied Physics 39(3) (2006) 541-546 [83] F.R. Al-Solamy, A.A. Al-Ghamdi, W.E. Mahmoud, Polym. Adv. Tech. 23(3) (2012) 478-482 [84] W.E. Mahmoud, E.H. El-Mossalamy, H.M. Arafa, J. Appl. Polym. Science 121(1) (2011) 502-507

11

[85] W.E. Mahmoud, A.A. Al-Ghamdi, F.R. Al-Solamy,

Polym. Adv. Tech. 23(2)

(2012) 161-165 [86] W.E. Mahmoud, J. Appl. Polym. Science 123(5) (2012) 2667-2675 [87] W.E. Mahmoud, A.A. Al-Ghamdi, F. Al-Agel, Polym. Adv. Tech. 22(12) (2011) 2055-2061 [88] W.E. Mahmoud, F. Al-Marzouki, S. Al-Ameer, F. Al-Hazmi, J. Applied Crystallography 45(2) (2012) 182-185

of

[89] W. Shirbeeny, W.E. Mahmoud, Sens. Actuators, B: Chemical 191 (2014) 102-107 [90] P.M. Price, W.E. Mahmoud, A.A. Al-Ghamdi, L.M. Bronstein, Front. Chem. 6 (2018) 619

ro

[91] W.E. Mahmoud, Polym. Adv. Tech. 22(12) (2011) 2550-2555

-p

[92] W.E. Mahmoud, J. Physics D: Applied Physics 42(15) (2009) 155502

[93] T. Blensdorf, A. Joenathan, M. Hunt, et al., J. Mater. Chem. A 5(7) (2017) 3493-

re

3502

[94] H.A. Al-Khanbashi, W. Shirbeeny, A.A. Al-Ghamdi, et al., Ceramics International 40(1 PART B) (2014) 1927-1932

7984-7994

lP

[95] A. Alshahrie, S. Joudakzis, A.A. Al-Ghamdi, et al., Ceram. Intern. 45(6) (2019)

ur na

[96] H.S. Al-Ghamdi, W.E. Mahmoud, J. Luminescence 145 (2014) 880-883 [97] R. Easterday, O. Sanchez-Felix, Y. Losovyj, et al., Catalys. Sci. Techn. 5(3) (2015) 1902-1910

Jo

Figure captions

Figure 1: (a) The XRD diffraction and (b) The variation of crystallite size and lattice constant against Tb ions for Tb-doped ZnS nanocrystals. Figure 2: The TEM images of the Tb-doped ZnS QDs at (a) 0 at%, (b) 2 at%, (c) 4 at% and (d) 6 at% . Figure 3: (a) The absorption spectra of the Tb-doped ZnS QDs and (b) Tauc’s plot Figure 4: The luminescence spectra of the Tb-doped ZnS QDs. 12

Figure 5: The variation of (a) Pl intensity and (b) quantum yield with Tb ions. Figure 6: Labeling of caveolin-1 protein in the lung cancer with (a) organic dyes and (b) QD probes. Figure 7: (a) The charge transfer mechanism and (b) The PL emission regime for Tbdoped ZnS QDs.

(311)

5

0.552 0.55 0.548 0.546

-p

(220)

b

0.554

3 2

0.544

a

0.542

1

R

0.54

re

4

0.538

30

35

40

45 2q

50

55

60

lP

25

Jo

ur na

Figure 1

13

0

0

2

4

Tb-content (at.%)

6

Crystallite size (nm)

Zn₀.₉₄Tb₀.₀₆S

6

0.556

of

Zn₀.₉₆Tb₀.₀₄S

0.558

ro

Zn₀.₉₈Tb₀.₀₂S

Intensity (a.u.)

(111)

ZnS

Lattice constnat (nm)

a

a

d=0.55 nm

c

d=0.58 nm

d

re

Figure 2

-p

ro

of

d=0.57 nm

b

d=0.56nm

300

Zn₀.₉₆Tb₀.₀₄S

10

ur na 320 340 360 380 Wavelength (nm)

400

(ahn)2 (eV.Cm-1)2

Zn₀.₉₈Tb₀.₀₂S

12

Zn₀.₉₄Tb₀.₀₆S

Jo

Absortion (a.u.)

a

14

lP

ZnS

ZnS

b

Zn₀.₉₈Tb₀.₀₂S Zn₀.₉₆Tb₀.₀₄S Zn₀.₉₄Tb₀.₀₆S

8 6 4 2 0 3.2

3.4

3.6 hn (eV)

Figure 3

14

3.8

8000

ZnS

7000

Zn₀.₉₈Tb₀.₀₂S Zn₀.₉₆Tb₀.₀₄S

5000

Zn₀.₉₄Tb₀.₀₆S

PL intensity

6000 4000 3000 2000 1000

200 250 300 350 400 450 500 l (nm)

-p

ro

Figure 4

of

0

90 80

Qauntum yield (%)

6000 4000 2000

ur na

0

0

b

re

a

8000

lP

Luminescence intensity (a.u.)

10000

2

4

70 60 50 40 30 20 10

6

0 0

Tb-content (at.%)

2

4

Tb-content (at.%)

Jo

Figure 5

15

6

a

ro

of

b

PL intensity

lP

b

400

Figure 7

Jo

ur na

a

re

-p

Figure 6

16

5D →7F 4 5

5D →7F 4 4

450

5D →7F 4

500

l (nm)

550