Detection of Luminescence Centers in Cu-doped Cd0.3Zn0.7S Quantum Dots by Synchronous Luminescence Spectroscopy
Main Article Content
Abstract
The identification of luminescence centers in Cu-doped ternary CdZnS quantum dots (QDs) remains challenging because the broad visible emission generally arises from multiple overlapping radiative transitions, making peak assignment highly dependent on indirect evidence. In this work, the luminescence mechanism of Cu-doped Cd0.3Zn0.7S QDs synthesized by a colloidal method was systematically investigated by combining X-ray diffraction (XRD), UV-Vis absorption, photoluminescence (PL), and synchronous luminescence (SL) spectroscopy. XRD showed a zinc-blende CdZnS alloy structure with no detectable secondary crystalline phase, while the first excitonic absorption yielded an optical band gap of 3.172 eV. The PL spectrum exhibits a narrow band-edge emission at 403 nm together with an intense broad visible emission centered at 554 nm. Unlike conventional PL, SL spectroscopy resolves the broad emission into three spectroscopically distinct bands centered at approximately 445, 488 and 503 nm, providing additional spectroscopic constraints for identifying the corresponding radiative transitions. Based on the complementary structural and spectroscopic evidence obtained in this work together with previously reported first-principles defect calculations and Cu-related luminescence mechanisms in ZnS-based materials, a semi-quantitative, evidence-integrated energy-level model is proposed to consistently interpret the observed emissions in terms of Cu-related acceptor states and intrinsic donor/acceptor defect states within the CdZnS alloy lattice. The present approach demonstrates that integrating SL with conventional structural and optical characterization provides a more reliable approach for identifying the dominant radiative recombination pathways in Cu-doped semiconductor QDs than assignment based solely on emission wavelengths.
Keywords:
Cu-doped CdZnS quantum dots; synchronous luminescence spectroscopy; luminescence centers; defect-related emission; radiative recombination.
References
[1] I. Yadav, Dh. S. Ahlawat, Effect of Dopant Concentration on Structural and Optical Properties of Cd0.7Zn0.3S semiconducting nanocrystals, Mater. Sci. Eng. B, Vol. 252, 2020, pp. 114450(9), https://doi.org/10.1016/j.mseb.2019.114450.
[2] C. Li, P. Wu, Cu‐doped Quantum Dots: A New Class of Near‐Infrared Emitting Fluorophores for Bioanalysis and Bioimaging, Luminescence, Vol. 34, 2019, pp. 782-789, https://doi.org/10.1002/bio.3679.
[3] M. Kaur, A. Sharma, O. Erdem, A. Kumar, H.V. Demir, M. Sharma, Understanding the Suitable Alloying Conditions for Highly Efficient Cu- and Mn-doped Zn1-xCdxS/ZnS Core-Shell Quantum Dots, Opt. Mater.,
Vol. 145, 2023, pp. 114471, https://doi.org/10.1016/j.optmat.2023.114471.
[4] P. Wu, X. P. Yan, Doped Quantum Dots for Chemo/Biosensing and Bioimaging, Chem. Soc. Rev., Vol. 42, 2013, pp. 5489-5521, https://doi.org/10.1039/C3CS60017C.
[5] M. Liu, N. Yazdani, M. Yarema, M. Jansen, V. Wood, E. H. Sargent, Colloidal Quantum Dot Electronics, Nat. Electron., Vol. 4, 2021, pp. 548-558, https://doi.org/10.1038/s41928-021-00632-7.
[6] N. Pradhan, X. Peng, Efficient and Color-tunable Mn-doped ZnSe Nanocrystal Emitters: Control of Optical Performance Via Greener Synthetic Chemistry, J. Am. Chem. Soc., Vol. 129, 2007, pp. 3339-3347, https://doi.org/10.1021/ja068360v.
[7] X. Yuan, J. Hua, R. Zeng, D. Zhu, W. Ji, P. Jing, X. Meng, J. Zhao, H. Li, Efficient white Light-emitting Diodes Based on Cu-doped ZnInS/ZnS Core/Shell Quantum Dots, Nanotechnology, Vol. 25, 2014, pp. 435202, https://doi.org/10.1088/0957-4484/25/43/435202.
[8] D. Y. Jo, D. Kim, J. H. Kim, H. Chae, H. J. Seo, Y. R. Do, H. Yang, Tunable white fluorescent Copper Gallium Sulfide Quantum Dots Enabled by Mn Doping, ACS Appl. Mater. Interfaces, Vol. 8, 2016, pp. 12291-12297, https://doi.org/10.1021/acsami.6b01763.
[9] A. J. Nozik, M. C. Beard, J. M. Luther, M. Law, R. J. Ellingson, J. C. Johnson, Semiconductor Quantum Dots and Quantum dot Arrays and Applications of Multiple Exciton Generation to Third-generation Photovoltaic Solar Cells, Chem. Rev., Vol. 110, 2010, pp. 6873-6890, https://doi.org/10.1021/cr900289f.
[10] Z. Yang, C. Y. Chen, P. Roy, H. T. Chang, Quantum Dot-sensitized Solar Cells Incorporating Nanomaterials, Chem. Commun., Vol. 47, 2011, pp. 9561-9571, https://doi.org/10.1039/C1CC11317H.
[11] T. S. Kanchana, T. Sivakumar, P. Venkateswara, Enhanced Photocatalytic Properties of ZnS/CdS/ZnCdS catalysts under visible light irradiation, J. Mol. Struct., Vol. 1265, 2022, pp. 133375, https://doi.org/10.1016/j.molstruc.2022.133375.
[12] C. M. Tyrakowski, P. T. Snee, A Primer on the Synthesis, Water-Solubilization, and Functionalization of Quantum Dots, Their Use As Biological Sensing Agents, and Present Status, Phys. Chem. Chem. Phys., Vol. 16, 2014, pp. 837-855, https://doi.org/10.1039/C3CP53502A.
[13] J. Zhu, S. Mei, W. Yang, G. Zhang, Q. Chen, W. Zhang, R. Guo, Tunable emission of Cu (Mn)-doped ZnInS quantum dots via dopant interaction, J. Colloid Interface Sci., Vol. 506, 2017, pp. 27-35, https://doi.org/10.1016/j.jcis.2017.06.043.
[14] Kr. Pradeep, R. Viswanatha, Mechanism of Mn emission: Energy Transfer vs Charge Transfer Dynamics in Mn-Doped Quantum Dots, APL Mater., Vol. 8, 2020, pp. 020901, https://doi.org/10.1063/1.5140888.
[15] H. Nishimura, K. Enomoto, Y. J. Pu, D. Kim, Hydrothermal Synthesis of Water-soluble Mn-and Cu-doped CdSe Quantum Dots with Multi-shell Structures and their Photoluminescence Properties, RSC Adv., Vol. 12, 2022,
pp. 6255-6264, https://doi.org/10.1039/D1RA08491G.
[16] S. Cao, C. Li, L. Wang, M. Shang, G. Wei, J. Zheng, W. Yang, Long-lived and Well Resolved Mn2+ ion Emissions in CuInS-ZnS Quantum Dots, Sci. Rep., Vol. 4, 2014, pp. 7510, https://doi.org/10.1038/srep07510.
[17] W. Zhang, X. Zhou, X. Zhong, One-pot Non-Injection Synthesis of Cu-doped ZnxCd1-xS Nanocrystals, Inorg. Chem., Vol. 51, 2012, pp. 3579-3587, https://doi.org/10.1021/ic2024023.
[18] R. Zeng, R. Shen, Y. Zhao, X. Li, Aqueous Synthesis of Cu-doped ZnCdS/ZnS Core/Shell Nanocrystals with a New and Highly Reactive Sulfur Source, Nanotechnology, Vol. 25, 2014, pp. 135602(9), https://doi.org/10.1088/0957-4484/25/13/135602.
[19] N. Pradhan, D. D. Sarma, Advances in Light-Emitting Doped Semiconductor Nanocrystals, J. Phys. Chem. Lett., Vol. 2, 2011, pp. 2818-2826, https://doi.org/10.1021/jz201132s.
[20] A. K. Chawla, S. Singhal, S. Nagar, H. O. Gupta, R. Chandra, Study of Composition Dependent Structural, Optical, and Magnetic Properties of Cu-doped Zn1-xCdxS Nanoparticles, J. Appl. Phys., Vol. 108, 2010,
pp. 123519(7), https://doi.org/10.1063/1.3524516.
[21] M. A. Osman, A. G. A. Elrahim, Excitation Wavelength Dependent Photoluminescence Emission Behavior, UV Induced Photoluminescence Enhancement and Optical Gap Tuning of Zn0.45Cd0.55S Nanoparticles for Optoelectronic Applications, Opt. Mater., Vol. 77, 2018, pp. 1-12, https://doi.org/10.1016/j.optmat.2018.01.011.
[22] Phi Van Thang, Ho Van Tuyen, Vu Xuan Quang, Nguyen Thi Thuy Lieu, Nguyen Trong Thanh, Nguyen Xuan Nghia, Detection of Luminescence Centers in Colloidal Cd0.3Zn0.7S Nanocrystals by Synchronous Luminescence Spectroscopy, Commun. Phys., Vol. 30, 2020, pp. 181-187, https://doi.org/10.15625/0868-3166/30/2/13819.
[23] D. S. Ahlawat, I. Yadav, Optical, Morphological and Thermal Investigation of Cu Doped Ternary Semiconducting (Cd1-xZnxS:Cu) Nanomaterials, Opt. Mater., Vol. 119, 2021, pp. 111377, https://doi.org/10.1016/j.optmat.2021.111377.
[24] P. K. Narayanan, P. Soni, R. S. Srinivasa, S. S. Talwar, S. S. Major, Strong and Tunable Blue Luminescence from Cd1 xZnxS Alloy Nanocrystallites Grown in Langmuir-Blodgett Multilayers, J. Phys. Chem. C, Vol. 117, 2013, pp. 4314-4325, https://doi.org/10.1021/jp312546a.
[25] A. A. Eiroa, G. D. Armas, J. M. Estela, V. Cerda, Critical Approach to Synchronous Spectrofluorimetry, Trends Anal. Chem., Vol. 29, 2010, pp. 885-901, https://doi.org/10.1016/j.trac.2010.04.010.
[26] A. Samokhvalov, Analysis of Various Solid Samples by Synchronous Fluorescence Spectroscopy and Related Methods: A review, Talanta, Vol. 216, 2020, pp. 120944, https://doi.org/10.1016/j.talanta.2020.120944.
[27] V. D. Tuan, Multicomponent Analysis by Synchronous Luminescence Spectrometry, Anal. Chem., Vol. 50, 1978, pp. 396-401, https://doi.org/10.1021/ac50025a010.
[28] D. Patra, T. H. Ghaddar, Application of Synchronous Fluorescence Scan Spectroscopy for Size Dependent Simultaneous Analysis of CdTe Nanocrystals and their Mixtures, Talanta, Vol. 77, 2009, pp. 1549-1554, https://doi.org/10.1016/j.talanta.2008.09.007.
[29] S. Taylor, A. Samokhvalov, Water as Probe Molecule For Midgap States in Nanocrystalline Strontium Titanate by Conventional and Synchronous Luminescence Spectroscopy under Ambient Conditions, Spectrochimica Acta Part A: Mol. Biomol. Spectrosc., Vol. 174, 2017, pp. 54-61, https://doi.org/10.1016/j.saa.2016.11.011.
[30] A. Alzahrani, A. Samokhvalov, Porous Calcium Titanate and Sorption and Desorption of Water under Ambient Conditions: A Study by Conventional and Synchronous Luminescence Spectroscopy, J. Porous Mater., Vol. 24, 2017, pp. 1145-1154, https://doi.org/10.1007/s10934-016-0354-1.
[31] A. Samokhvalov, Trap Emission By Nanocrystalline Anatase in Visible Range Studied by Conventional and Synchronous Luminescence Spectroscopy: Adsorption and Desorption of Water Vapor, J. Lumin., Vol. 192, 2017, pp. 388-396, https://doi.org/10.1016/j.jlumin.2017.07.009.
[32] A. Samokhvalov, Visible Emission in Nanocrystalline Rutile: Free Exciton and Water as Probes for Midgap States in Adsorption/Desorption Using Conventional and Synchronous Luminescence Spectroscopy, J. Phys. Chem. C, Vol. 121, 2017, pp. 21985-21994, https://doi.org/10.1021/acs.jpcc.7b02540.
[33] W. Q. Peng, G. W. Cong, S. C. Qu, Z. G. Wang, Synthesis and Photoluminescence of ZnS:Cu Nanoparticles, Opt. Mater., Vol. 29, 2006, pp. 313-317, https://doi.org/10.1016/j.optmat.2005.10.003.
[34] K. Hoang, C. Latouche, S. Jobic, Defect Energy Levels and Persistent Luminescence in Cu-doped ZnS, Comput. Mater. Sci., Vol. 163, 2019, pp. 63-67, https://doi.org/10.1016/j.commatsci.2019.03.016.
[35] J. C. Wu, J. Zheng, P. Wu, R. Xu, Study of Native Defects and Transition-Metal (Mn, Fe, Co, and Ni) Doping in a Zinc-Blende CdS Photocatalyst by DFT and Hybrid DFT Calculations, J. Phys. Chem. C, Vol. 115, 2011,
pp. 5675-5682, https://doi.org/10.1021/jp109567c.
[36] Y. Chen, L. Huang, S. Li, D. Pan, Aqueous Synthesis of Glutathione-capped Cu+ and Ag+-doped ZnxCd1-xS Quantum Dots with Full Color Emission, J. Mater. Chem. C, Vol. 1, 2013, pp. 751-756, https://doi.org/10.1039/c2tc00107a.
[37] S. C. Erwin, L. Zu, M. I. Haftel, A. L. Efros, T. A. Kennedy, D. J. Norris, Doping Semiconductor Nanocrystals, Nature, Vol. 436, 2005, pp. 91-94, https://doi.org/10.1038/nature03832.
[38] M. A. Iqbal, M. Malik, A. Zahid, Md. R. Islam, I. D. A. Ramirez, M. A. Bahrani, Unveiling Concentration Effects on the Structural and Optoelectronic Characteristics of Zn1-xCdxS (x = 0, 0.25, 0.50, 0.75, 1) Cubic Semiconductors: A Theoretical Study, RSC Adv., Vol. 12, 2022, pp. 22783-22791, https://doi.org/10.1039/d2ra03850a.
[39] S. J. Kwon, H. M. Jeong, K. Jung, D. H. Ko, H. Ko, I. K. Han, G. T. Kim, J. G. Park, Structural Origin of the Band Gap Anomaly of Quaternary Alloy CdxZn1-xSySe1-y Nanowires, Nanobelts, and Nanosheets in the Visible Spectrum, ACS Nano, Vol. 9, 2015, pp. 5486-5499, https://doi.org/10.1021/acsnano.5b01472.
[40] H. Alehdaghi, M. Marandi, M. Molaei, A. Irajizad, N. Taghavinia, Facile Synthesis of Gradient Alloyed ZnxCd1-xS Nanocrystals Using a Microwave-Assisted Method, J. Alloys Compd., Vol. 586, 2014, pp. 380-384, https://doi.org/10.1016/j.jallcom.2013.09.190.
[41] X. Zhong, Y. Feng, W. Knoll, M. Han, Alloyed ZnxCd1-xS Nanocrystals with Highly Narrow Luminescence Spectral Width, J. Am. Chem. Soc., Vol. 125, 2003, pp. 13559-13563, https://doi.org/10.1021/ja036683a.
[42] Z. Chen, Q. Tian, Y. Song, J. Yang, J. Hu, One-pot Synthesis of ZnxCd1-xS Nanocrystals with Tunable Optical Properties from Molecular Precursors, J. Alloys Compd., Vol. 506, 2010, pp. 804-810, https://doi.org/10.1016/j.jallcom.2010.07.075.
[43] J. Kim, J. Lee, H. S. Jang, D. Y. Jeon, H. Yang, Widely Tunable Emissions of Colloidal Zn x Cd1-x Se Alloy Quantum Dots Using a Constant Zn/Cd Precursor Ratio, J. Nanosci. Nanotechnol., Vol. 11, 2011, pp. 725-729, https://doi.org/10.1166/jnn.2011.3193.
[44] L. Wang, Y. Jiang, C. Wang, W. Wang, B. Cao, M. Niu, Y. Qian, Composition-controllable Synthesis and Optical Properties of Non-Integral Stoichiometry Compound ZnxCd1-xS nanorods, J. Alloys Compd., Vol. 454, 2008, pp. 255-260, https://doi.org/10.1016/j.jallcom.2006.12.046.
[45] K. Tomihira, D. Kim, M. Nakayama, Optical Properties of ZnS-CdS Alloy Quantum Dots Prepared by a Colloidal Method, J. Lumin., Vol. 112, 2005, pp. 131-135, https://doi.org/10.1016/j.jlumin.2004.09.011.
[46] J. Manam, V. Chatterjee, S. Das, A. Choubey, S. K. Sharma, Preparation, Characterization and Study of Optical Properties of ZnS Nanophosphor, J. Lumin., Vol. 130, 2010, pp. 292-297, https://doi.org/10.1016/j.jlumin.2009.09.005.
[47] X. Xu, Y. Zhao, E. J. Sie, Y. Lu, B. Liu, S. A. Ekahana, X. Ju, Q. Jiang, J. Wang, H. Sun, T. C. Sum, C. H. A. Huan, Y. P. Feng, Q. Xiong, Dynamics of Bound Exciton Complexes in CdS Nanobelts, ACS Nano, Vol. 5, 2011, pp. 3660-3669, https://doi.org/10.1021/nn2008832.
[2] C. Li, P. Wu, Cu‐doped Quantum Dots: A New Class of Near‐Infrared Emitting Fluorophores for Bioanalysis and Bioimaging, Luminescence, Vol. 34, 2019, pp. 782-789, https://doi.org/10.1002/bio.3679.
[3] M. Kaur, A. Sharma, O. Erdem, A. Kumar, H.V. Demir, M. Sharma, Understanding the Suitable Alloying Conditions for Highly Efficient Cu- and Mn-doped Zn1-xCdxS/ZnS Core-Shell Quantum Dots, Opt. Mater.,
Vol. 145, 2023, pp. 114471, https://doi.org/10.1016/j.optmat.2023.114471.
[4] P. Wu, X. P. Yan, Doped Quantum Dots for Chemo/Biosensing and Bioimaging, Chem. Soc. Rev., Vol. 42, 2013, pp. 5489-5521, https://doi.org/10.1039/C3CS60017C.
[5] M. Liu, N. Yazdani, M. Yarema, M. Jansen, V. Wood, E. H. Sargent, Colloidal Quantum Dot Electronics, Nat. Electron., Vol. 4, 2021, pp. 548-558, https://doi.org/10.1038/s41928-021-00632-7.
[6] N. Pradhan, X. Peng, Efficient and Color-tunable Mn-doped ZnSe Nanocrystal Emitters: Control of Optical Performance Via Greener Synthetic Chemistry, J. Am. Chem. Soc., Vol. 129, 2007, pp. 3339-3347, https://doi.org/10.1021/ja068360v.
[7] X. Yuan, J. Hua, R. Zeng, D. Zhu, W. Ji, P. Jing, X. Meng, J. Zhao, H. Li, Efficient white Light-emitting Diodes Based on Cu-doped ZnInS/ZnS Core/Shell Quantum Dots, Nanotechnology, Vol. 25, 2014, pp. 435202, https://doi.org/10.1088/0957-4484/25/43/435202.
[8] D. Y. Jo, D. Kim, J. H. Kim, H. Chae, H. J. Seo, Y. R. Do, H. Yang, Tunable white fluorescent Copper Gallium Sulfide Quantum Dots Enabled by Mn Doping, ACS Appl. Mater. Interfaces, Vol. 8, 2016, pp. 12291-12297, https://doi.org/10.1021/acsami.6b01763.
[9] A. J. Nozik, M. C. Beard, J. M. Luther, M. Law, R. J. Ellingson, J. C. Johnson, Semiconductor Quantum Dots and Quantum dot Arrays and Applications of Multiple Exciton Generation to Third-generation Photovoltaic Solar Cells, Chem. Rev., Vol. 110, 2010, pp. 6873-6890, https://doi.org/10.1021/cr900289f.
[10] Z. Yang, C. Y. Chen, P. Roy, H. T. Chang, Quantum Dot-sensitized Solar Cells Incorporating Nanomaterials, Chem. Commun., Vol. 47, 2011, pp. 9561-9571, https://doi.org/10.1039/C1CC11317H.
[11] T. S. Kanchana, T. Sivakumar, P. Venkateswara, Enhanced Photocatalytic Properties of ZnS/CdS/ZnCdS catalysts under visible light irradiation, J. Mol. Struct., Vol. 1265, 2022, pp. 133375, https://doi.org/10.1016/j.molstruc.2022.133375.
[12] C. M. Tyrakowski, P. T. Snee, A Primer on the Synthesis, Water-Solubilization, and Functionalization of Quantum Dots, Their Use As Biological Sensing Agents, and Present Status, Phys. Chem. Chem. Phys., Vol. 16, 2014, pp. 837-855, https://doi.org/10.1039/C3CP53502A.
[13] J. Zhu, S. Mei, W. Yang, G. Zhang, Q. Chen, W. Zhang, R. Guo, Tunable emission of Cu (Mn)-doped ZnInS quantum dots via dopant interaction, J. Colloid Interface Sci., Vol. 506, 2017, pp. 27-35, https://doi.org/10.1016/j.jcis.2017.06.043.
[14] Kr. Pradeep, R. Viswanatha, Mechanism of Mn emission: Energy Transfer vs Charge Transfer Dynamics in Mn-Doped Quantum Dots, APL Mater., Vol. 8, 2020, pp. 020901, https://doi.org/10.1063/1.5140888.
[15] H. Nishimura, K. Enomoto, Y. J. Pu, D. Kim, Hydrothermal Synthesis of Water-soluble Mn-and Cu-doped CdSe Quantum Dots with Multi-shell Structures and their Photoluminescence Properties, RSC Adv., Vol. 12, 2022,
pp. 6255-6264, https://doi.org/10.1039/D1RA08491G.
[16] S. Cao, C. Li, L. Wang, M. Shang, G. Wei, J. Zheng, W. Yang, Long-lived and Well Resolved Mn2+ ion Emissions in CuInS-ZnS Quantum Dots, Sci. Rep., Vol. 4, 2014, pp. 7510, https://doi.org/10.1038/srep07510.
[17] W. Zhang, X. Zhou, X. Zhong, One-pot Non-Injection Synthesis of Cu-doped ZnxCd1-xS Nanocrystals, Inorg. Chem., Vol. 51, 2012, pp. 3579-3587, https://doi.org/10.1021/ic2024023.
[18] R. Zeng, R. Shen, Y. Zhao, X. Li, Aqueous Synthesis of Cu-doped ZnCdS/ZnS Core/Shell Nanocrystals with a New and Highly Reactive Sulfur Source, Nanotechnology, Vol. 25, 2014, pp. 135602(9), https://doi.org/10.1088/0957-4484/25/13/135602.
[19] N. Pradhan, D. D. Sarma, Advances in Light-Emitting Doped Semiconductor Nanocrystals, J. Phys. Chem. Lett., Vol. 2, 2011, pp. 2818-2826, https://doi.org/10.1021/jz201132s.
[20] A. K. Chawla, S. Singhal, S. Nagar, H. O. Gupta, R. Chandra, Study of Composition Dependent Structural, Optical, and Magnetic Properties of Cu-doped Zn1-xCdxS Nanoparticles, J. Appl. Phys., Vol. 108, 2010,
pp. 123519(7), https://doi.org/10.1063/1.3524516.
[21] M. A. Osman, A. G. A. Elrahim, Excitation Wavelength Dependent Photoluminescence Emission Behavior, UV Induced Photoluminescence Enhancement and Optical Gap Tuning of Zn0.45Cd0.55S Nanoparticles for Optoelectronic Applications, Opt. Mater., Vol. 77, 2018, pp. 1-12, https://doi.org/10.1016/j.optmat.2018.01.011.
[22] Phi Van Thang, Ho Van Tuyen, Vu Xuan Quang, Nguyen Thi Thuy Lieu, Nguyen Trong Thanh, Nguyen Xuan Nghia, Detection of Luminescence Centers in Colloidal Cd0.3Zn0.7S Nanocrystals by Synchronous Luminescence Spectroscopy, Commun. Phys., Vol. 30, 2020, pp. 181-187, https://doi.org/10.15625/0868-3166/30/2/13819.
[23] D. S. Ahlawat, I. Yadav, Optical, Morphological and Thermal Investigation of Cu Doped Ternary Semiconducting (Cd1-xZnxS:Cu) Nanomaterials, Opt. Mater., Vol. 119, 2021, pp. 111377, https://doi.org/10.1016/j.optmat.2021.111377.
[24] P. K. Narayanan, P. Soni, R. S. Srinivasa, S. S. Talwar, S. S. Major, Strong and Tunable Blue Luminescence from Cd1 xZnxS Alloy Nanocrystallites Grown in Langmuir-Blodgett Multilayers, J. Phys. Chem. C, Vol. 117, 2013, pp. 4314-4325, https://doi.org/10.1021/jp312546a.
[25] A. A. Eiroa, G. D. Armas, J. M. Estela, V. Cerda, Critical Approach to Synchronous Spectrofluorimetry, Trends Anal. Chem., Vol. 29, 2010, pp. 885-901, https://doi.org/10.1016/j.trac.2010.04.010.
[26] A. Samokhvalov, Analysis of Various Solid Samples by Synchronous Fluorescence Spectroscopy and Related Methods: A review, Talanta, Vol. 216, 2020, pp. 120944, https://doi.org/10.1016/j.talanta.2020.120944.
[27] V. D. Tuan, Multicomponent Analysis by Synchronous Luminescence Spectrometry, Anal. Chem., Vol. 50, 1978, pp. 396-401, https://doi.org/10.1021/ac50025a010.
[28] D. Patra, T. H. Ghaddar, Application of Synchronous Fluorescence Scan Spectroscopy for Size Dependent Simultaneous Analysis of CdTe Nanocrystals and their Mixtures, Talanta, Vol. 77, 2009, pp. 1549-1554, https://doi.org/10.1016/j.talanta.2008.09.007.
[29] S. Taylor, A. Samokhvalov, Water as Probe Molecule For Midgap States in Nanocrystalline Strontium Titanate by Conventional and Synchronous Luminescence Spectroscopy under Ambient Conditions, Spectrochimica Acta Part A: Mol. Biomol. Spectrosc., Vol. 174, 2017, pp. 54-61, https://doi.org/10.1016/j.saa.2016.11.011.
[30] A. Alzahrani, A. Samokhvalov, Porous Calcium Titanate and Sorption and Desorption of Water under Ambient Conditions: A Study by Conventional and Synchronous Luminescence Spectroscopy, J. Porous Mater., Vol. 24, 2017, pp. 1145-1154, https://doi.org/10.1007/s10934-016-0354-1.
[31] A. Samokhvalov, Trap Emission By Nanocrystalline Anatase in Visible Range Studied by Conventional and Synchronous Luminescence Spectroscopy: Adsorption and Desorption of Water Vapor, J. Lumin., Vol. 192, 2017, pp. 388-396, https://doi.org/10.1016/j.jlumin.2017.07.009.
[32] A. Samokhvalov, Visible Emission in Nanocrystalline Rutile: Free Exciton and Water as Probes for Midgap States in Adsorption/Desorption Using Conventional and Synchronous Luminescence Spectroscopy, J. Phys. Chem. C, Vol. 121, 2017, pp. 21985-21994, https://doi.org/10.1021/acs.jpcc.7b02540.
[33] W. Q. Peng, G. W. Cong, S. C. Qu, Z. G. Wang, Synthesis and Photoluminescence of ZnS:Cu Nanoparticles, Opt. Mater., Vol. 29, 2006, pp. 313-317, https://doi.org/10.1016/j.optmat.2005.10.003.
[34] K. Hoang, C. Latouche, S. Jobic, Defect Energy Levels and Persistent Luminescence in Cu-doped ZnS, Comput. Mater. Sci., Vol. 163, 2019, pp. 63-67, https://doi.org/10.1016/j.commatsci.2019.03.016.
[35] J. C. Wu, J. Zheng, P. Wu, R. Xu, Study of Native Defects and Transition-Metal (Mn, Fe, Co, and Ni) Doping in a Zinc-Blende CdS Photocatalyst by DFT and Hybrid DFT Calculations, J. Phys. Chem. C, Vol. 115, 2011,
pp. 5675-5682, https://doi.org/10.1021/jp109567c.
[36] Y. Chen, L. Huang, S. Li, D. Pan, Aqueous Synthesis of Glutathione-capped Cu+ and Ag+-doped ZnxCd1-xS Quantum Dots with Full Color Emission, J. Mater. Chem. C, Vol. 1, 2013, pp. 751-756, https://doi.org/10.1039/c2tc00107a.
[37] S. C. Erwin, L. Zu, M. I. Haftel, A. L. Efros, T. A. Kennedy, D. J. Norris, Doping Semiconductor Nanocrystals, Nature, Vol. 436, 2005, pp. 91-94, https://doi.org/10.1038/nature03832.
[38] M. A. Iqbal, M. Malik, A. Zahid, Md. R. Islam, I. D. A. Ramirez, M. A. Bahrani, Unveiling Concentration Effects on the Structural and Optoelectronic Characteristics of Zn1-xCdxS (x = 0, 0.25, 0.50, 0.75, 1) Cubic Semiconductors: A Theoretical Study, RSC Adv., Vol. 12, 2022, pp. 22783-22791, https://doi.org/10.1039/d2ra03850a.
[39] S. J. Kwon, H. M. Jeong, K. Jung, D. H. Ko, H. Ko, I. K. Han, G. T. Kim, J. G. Park, Structural Origin of the Band Gap Anomaly of Quaternary Alloy CdxZn1-xSySe1-y Nanowires, Nanobelts, and Nanosheets in the Visible Spectrum, ACS Nano, Vol. 9, 2015, pp. 5486-5499, https://doi.org/10.1021/acsnano.5b01472.
[40] H. Alehdaghi, M. Marandi, M. Molaei, A. Irajizad, N. Taghavinia, Facile Synthesis of Gradient Alloyed ZnxCd1-xS Nanocrystals Using a Microwave-Assisted Method, J. Alloys Compd., Vol. 586, 2014, pp. 380-384, https://doi.org/10.1016/j.jallcom.2013.09.190.
[41] X. Zhong, Y. Feng, W. Knoll, M. Han, Alloyed ZnxCd1-xS Nanocrystals with Highly Narrow Luminescence Spectral Width, J. Am. Chem. Soc., Vol. 125, 2003, pp. 13559-13563, https://doi.org/10.1021/ja036683a.
[42] Z. Chen, Q. Tian, Y. Song, J. Yang, J. Hu, One-pot Synthesis of ZnxCd1-xS Nanocrystals with Tunable Optical Properties from Molecular Precursors, J. Alloys Compd., Vol. 506, 2010, pp. 804-810, https://doi.org/10.1016/j.jallcom.2010.07.075.
[43] J. Kim, J. Lee, H. S. Jang, D. Y. Jeon, H. Yang, Widely Tunable Emissions of Colloidal Zn x Cd1-x Se Alloy Quantum Dots Using a Constant Zn/Cd Precursor Ratio, J. Nanosci. Nanotechnol., Vol. 11, 2011, pp. 725-729, https://doi.org/10.1166/jnn.2011.3193.
[44] L. Wang, Y. Jiang, C. Wang, W. Wang, B. Cao, M. Niu, Y. Qian, Composition-controllable Synthesis and Optical Properties of Non-Integral Stoichiometry Compound ZnxCd1-xS nanorods, J. Alloys Compd., Vol. 454, 2008, pp. 255-260, https://doi.org/10.1016/j.jallcom.2006.12.046.
[45] K. Tomihira, D. Kim, M. Nakayama, Optical Properties of ZnS-CdS Alloy Quantum Dots Prepared by a Colloidal Method, J. Lumin., Vol. 112, 2005, pp. 131-135, https://doi.org/10.1016/j.jlumin.2004.09.011.
[46] J. Manam, V. Chatterjee, S. Das, A. Choubey, S. K. Sharma, Preparation, Characterization and Study of Optical Properties of ZnS Nanophosphor, J. Lumin., Vol. 130, 2010, pp. 292-297, https://doi.org/10.1016/j.jlumin.2009.09.005.
[47] X. Xu, Y. Zhao, E. J. Sie, Y. Lu, B. Liu, S. A. Ekahana, X. Ju, Q. Jiang, J. Wang, H. Sun, T. C. Sum, C. H. A. Huan, Y. P. Feng, Q. Xiong, Dynamics of Bound Exciton Complexes in CdS Nanobelts, ACS Nano, Vol. 5, 2011, pp. 3660-3669, https://doi.org/10.1021/nn2008832.