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UV photoluminescence from nanocrystalline tin oxide synthesized by a one-step hydrothermal method
Materials Letters ∎ (∎∎∎∎) ∎∎∎–∎∎∎
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Materials Letters journal homepage: www.elsevier.com/locate/matlet
UV photoluminescence from nanocrystalline tin oxide synthesized by a one-step hydrothermal method K. Vijayarangamuthu a,b,n, Shyama Rath a,c,n a
Department of Physics and Astrophysics, University of Delhi, Delhi 110007, India Department of Environmental Engineering, Inha University, Incheon 402-751, Republic of Korea c Department of Physics, Chulalongkorn University, Bangkok 10330, Thailand b
art ic l e i nf o
a b s t r a c t
Article history: Received 22 April 2015 Received in revised form 18 May 2015 Accepted 19 May 2015
Highly crystalline SnO2 nanocrystals with good size and shape uniformity were synthesized by a hydrothermal process. The highlight of this study is the observation of a sharp UV photoluminescence (PL) at 3.42 eV and a simultaneous absence of the broad defect-related visible PL emission. The PL emission is understood in the context of crystallinity, size/surface effects and oxygen vacancies as supported by the Raman spectra. The favorable structural and optical properties suggest their scope for UV light-emitting Q2 applications. & 2015 Elsevier B.V. All rights reserved.
Keywords: Tin oxide Hydrothermal Photoluminescence UV emission Raman
1. Introduction The large direct bandgap ( 3.6 eV) and a high exciton binding energy (130 meV) of SnO2 are favorable for room-temperature UV applications. However, the dipole-forbidden nature of its direct bandgap alongwith a commonly observed broad and intense deeplevel-defect-related visible emission restrict and overwhelm the band-edge emission. A modification of the electronic band structure, for example, by nanostructuring, could render the forbidden transition optically active [1–9]. In this respect, the hydrothermal wet synthesis method enables an excellent control over the size, shape and crystallinity [10–12]. However, optical studies have been limited and the UV photoluminescence (PL) was either absent, weak or broad [5,13]. The objective of our work is to exploit the advantages of hydrothermal method and we demonstrate morphologically uniform nanostructures with a sharp UV PL and a reduced concentration of defects.
used as the starting precursors without any further purification. A typical synthesis consists of dissolving 2.5 g of SnCl4 5H2O and 1.25 g of NaOH in a mixture containing equal volume of distilled water and ethylenediamine to form a slurry-like white precipitated solution. After 10 min of stirring, the solution was transferred into a teflon-lined stainless steel autoclave, which was maintained at 150 °C for 24 h and cooled naturally to room temperature. The product was centrifuged, filtered out, rinsed with alcohol and deionized water several times to remove impurities. The final product was dried at 100 °C for 60 min. The high-resolution x-ray diffraction (XRD) patterns were recorded with a Bruker D8 Advance x-ray diffractometer with a Cu Kα source (λ ¼1.5418 Å). Transmission electron microscopy (TEM) images were taken with a TECHNAI G2 300 kV instrument. MicroRaman measurements were performed using an in-Via Renishaw micro-Raman system with a 514.5 nm excitation. Low laser powers were used to avoid sample heating effects. The PL spectra were measured with a Horiba Jobin Yvon Fluorolog fluorescence spectrometer using a xenon lamp as the excitation source.
2. Experimental section SnCl4 5H2O and NaOH purchased from Sigma-Aldrich were n
Corresponding authors at: Department of Physics and Astrophysics, University of Delhi, Delhi 110007, India. E-mail addresses: [email protected] (K. Vijayarangamuthu), [email protected] (S. Rath).
3. Result and discussion The high-resolution XRD pattern of the synthesized SnO2 nanocrystals is shown in Fig. 1a. All the diffraction peaks could be indexed to the tetragonal rutile structure of SnO2 (JCPDS: 770448). The positions from JCPDS are also shown in the same figure
http://dx.doi.org/10.1016/j.matlet.2015.05.090 0167-577X/& 2015 Elsevier B.V. All rights reserved.
Please cite this article as: Vijayarangamuthu K, Rath S. UV photoluminescence from nanocrystalline tin oxide synthesized by a one-step hydrothermal method. Mater Lett (2015), http://dx.doi.org/10.1016/j.matlet.2015.05.090i
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K. Vijayarangamuthu, S. Rath / Materials Letters ∎ (∎∎∎∎) ∎∎∎–∎∎∎
for comparison. The lattice constants a and c calculated from the peaks of the (101) and (211) planes were 4.743 and 3.204 Å respectively, and match well with reported values. The sharp and intense peaks indicate good crystallinity. The high intensity along the (101) phase implies a horizontal growth direction of the elongated tetragonal structure. The average crystallite size was calculated to be around 10 nm using the Debye–Scherrer formula. Fig. 2(a and b) shows typical TEM images of the as-synthesized SnO2 nanoparticles. Uniformly shaped elongated structures with widths of around 7 nm are observed. The high-resolution TEM image (Fig. 2c) revealed a d-spacing corresponding to the (101) and (110) lattice planes of tetragonal SnO2 crystal (JCPDS: 770448). The continuous ring pattern with intense white dots in the
Fig. 1. (a) XRD pattern of hydrothermal SnO2 nanocrystals. The vertical red lines correspond to JCPDS card no: 77-0448.
Fig. 3. (a) Raman spectrum of hydrothermal SnO2 nanocrystals. (b) And (c) deconvolution of the Raman spectrum between 275 cm 1 and 375 cm 1, and 535 cm 1 and 700 cm 1 respectively.
Fig. 2. (a), (b) TEM images. (c) HR-TEM image with lattices spacing, and (d) selected-area-electron-diffraction pattern of SnO2 nanocrystals.
Please cite this article as: Vijayarangamuthu K, Rath S. UV photoluminescence from nanocrystalline tin oxide synthesized by a one-step hydrothermal method. Mater Lett (2015), http://dx.doi.org/10.1016/j.matlet.2015.05.090i
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K. Vijayarangamuthu, S. Rath / Materials Letters ∎ (∎∎∎∎) ∎∎∎–∎∎∎
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Fig. 4. PL spectrum of SnO2 nano-crystalline powder: excited with (a) 300 nm. Inset: is the amplified spectra in the 450–800 nm range. (b) 280, 290, and 300 nm.
selected-area-electron-diffraction (SAED) pattern (Fig. 2d) indicates the highly crystalline nature. The lattice spacing between the fringes match with the lattice spacing values of the (101), (110), (211), and (112) planes observed in the XRD pattern. The microscopic structure is further investigated by Raman spectroscopy. SnO2, with six atoms in its unit cell, has 18 vibrational modes in the first Brillouin zone. The A1g, B1g, B2g and Eg are Raman active [14] while the Eu modes are IR active and Ramansilent. Additional modes due to size restriction, vacancies, surface defects have also been reported [15] and which can be correlated to the light-emitting properties. Fig. 3a illustrates the room temperature micro-Raman spectra of the as-synthesized SnO2 nanostructures and their peak assignments are tabulated in Table S1. The Raman modes at 628 (A1g), 771 (B2g), and 476 cm 1 (Eg) confirm the crystalline and tetragonal structure. The broad mode observed between 260 and 370 cm 1 can be deconvoluted into three modes at 286, 307 and 337 cm 1 Fig. 3b. The mode at 307 cm 1 is related to a surface defect in small-sized particles [16]. The modes at 250, 286 and 337 are the Eu modes activated due to the small particle size and a destruction of the k wavevector selection rule [17,18]. The deconvolution of the broad structure between 540 and 700 cm 1 (Fig. 3c) shows a S1 mode at 576 cm 1 correlated to the presence of in-plane oxygen vacancies (OVs) [15], a A1g mode at 628 cm 1, and a fourth Eu mode at 605 cm 1. An annealing leads to a disappearance of the size-related Raman modes (Fig S1) and a blue-shift in the peak position of A1g mode to 632 cm 1 due to increase in the particle size and transformation to bulk. Fig. 4a shows the room temperature PL emission of SnO2 nanocrystals excited with 300 nm. Two distinct UV emissions are observed: one at around 362 nm (3.42 eV) with a FWHM of 7.3 nm, which is considerably sharper than that reported in previous studies [3,13]. Its energy is about 0.58 eV lower than the bandgap obtained from UV measurements and about 0.38 eV lower than that estimated from quantum confinement models (Supplementary information S2). It is therefore energetically too far to be assigned to near-band edge effects or excitonic effects. This radiative transition is assigned to the donor–acceptor-pair (DAP) recombination [2,3,8] with the donor defect associated with an oxygen vacancy. Its position is independent of excitation wavelength as shown in Fig. 4b. The second PL emission occurs at 383 nm (3.23 eV). Its position and intensity on the other hand, vary monotonically with a change in the excitation wavelength. It shifts to 395 (3.13 eV) and 408 nm (3.03 eV) for excitation wavelengths of 280 and 290 nm respectively. The in-plane OV and surface defects, whose presence is supported by the Raman modes at 576 and 307 cm 1 are responsible for this emission and their role in the PL properties were shown by density functional theory
calculations [19]. The different excitation wavelength dependence of the two PL peaks indicates their different origin. Finally, along with UV emission, the near-complete absence of the defect-related visible emission is a notable feature indicating a significantly low defect concentration. Its extent, as seen in Fig. 4a, is restricted only to the 660 –780 nm spectral range rather than the much broader visible emission generally reported. Its intensity is insignificant as compared to the UV emission. This emission is due to a small quantity of lattice oxygen vacancies supported by electron paramagnetic resonance studies (Fig S3) and whose complete elimination is unlikely in metal-oxide thin films and nanostructures.
4. Conclusions Highly crystalline SnO2 nanostructures, with uniformity in size and shape, were synthesized by a simple hydrothermal method. A sharp UV PL is observed due to a combination of crystallinity and small sizes. The visible emission is of negligible intensity and limited to a narrow spectral range. The light emission properties are correlated to the structural aspects investigated by Raman spectroscopy. The favorable structural and PL properties indicate the efficacy of the synthesis process and the feasibility of nanocrystalline SnO2 for UV light emitting applications.
Acknowledgment This work was supported by grants from CARS Project 05/P264/09-10 of Defence Research Development Organization, Delhi University R&D Grant, and Nanomission project of Department of Science and Technology, India. KV acknowledges Council of Scientific and Industrial Research, India for a senior research fellowship.
Appendix A. Supplementary Information Supplementary data associated with this article can be found in the online version at http://dx.doi.org/10.1016/j.matlet.2015.05. 090.
References [1] Li Y, Yin W, Deng R, Chen R, Chen J, Yan Q, et al. Realizing a SnO2-based ultraviolet light-emitting diode via breaking the dipole-forbidden rule. NPG
Please cite this article as: Vijayarangamuthu K, Rath S. UV photoluminescence from nanocrystalline tin oxide synthesized by a one-step hydrothermal method. Mater Lett (2015), http://dx.doi.org/10.1016/j.matlet.2015.05.090i
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K. Vijayarangamuthu, S. Rath / Materials Letters ∎ (∎∎∎∎) ∎∎∎–∎∎∎
Asia Mater. 2012;4:e30. [2] Blattner G, Klingshirn C, Helbig R. Impurity transitions in the photoluminescence spectra of SnO2. Solid State Commun. 1980;33:341–4. [3] Chen R, Xing GZ, Gao J, Zhang Z, Wu T, Sun HD. Characteristics of ultraviolet photoluminescence from high quality tin oxide nanowires. Appl. Phys. Lett. 2009;95:061908. [4] Kumar V, Kumar V, Som S, Neethling JH, Lee M, Ntwaeaborwa OM, et al. The role of surface and deep-level defects on the emission of tin oxide quantum dots. Nanotechnology 2014;25:135701. [5] Yang HY, Yu SF, Cheng CW, Tsang SH, Liang HK, Fan HJ. Randomly packed n-SnO2 nanorods/p-SiC heterojunction light-emitting diodes. Appl. Phys. Lett. 2009;95:201104. [6] Pan SS, Yu SF, Zhang WF, Zhu H, Lu W, Jin LM. Low threshold amplified spontaneous emission from tin oxide quantum dots: a instantiation of dipole transition silence semiconductors. Nanoscale. 2013;5:11561–7. [7] Zhu H, Yang D, Yu G, Zhang H, Yao K. A simple hydrothermal route for synthesizing SnO2 quantum dots. Nanotechnology 2006;17:2386. [8] Kar A, Stroscio MA, Dutta M, Kumari J, Meyyappan M. Observation of ultraviolet emission and effect of surface states on the luminescence from tin oxide nanowires. Appl. Phys. Lett. 2009;94:101905. [9] Vijayarangamuthu K, Rath S. Modification of the structural and optical properties of tin oxide nanoparticles by Co doping and thermal annealing. Appl. Phys. A 2014;114:1181–8. [10] Yu C, Yu JC, Wang F, Wen H, Tang Y. Growth of single-crystalline SnO2 nanocubes via a hydrothermal route. CrystEngComm 2010;12:341–3. [11] He Y, Li Y, Yu J, Qian Y. Chemical control synthesis of nanocrystalline SnO2 by
hydrothermal reaction. Mater. Lett. 1999;40:23–6. [12] Lupan O, Chow L, Chai G, Heinrich H, Park S, Schulte A. Synthesis of onedimensional SnO2 nanorods via a hydrothermal technique. Physica E 2009;41:533–6. [13] Lee EJH, Ribeiro C, Giraldi TR, Longo E, Leite ER, Varela JA. Photoluminescence in quantum-confined SnO2 nanocrystals: evidence of free exciton decay. Appl. Phys. Lett. 2004;84:1745–7. [14] Parlinski K, Kawazoe Y. Ab initio study of phonons in the rutile structure of under pressure. Eur. Phys. J. B. 2000;13:679–83. [15] Liu LZ, Xu JQ, Wu XL, Li TH, Shen JC, Chu PK. Optical identification of oxygen vacancy types in SnO2 nanocrystals. Appl. Phys. Lett. 2013;102:031916. [16] Ocaña M, Serna CJ, García-Ramos JV, Matijević E. A vibrational study of uniform SnO2 powders of various morphologies. Solid State Ion. 1993;63–65:170– 7. [17] Vijayarangamuthu K, Rath S. Nanoparticle size, oxidation state, and sensing response of tin oxide nanopowders using Raman spectroscopy. J. Alloy. Compd. 2014;610:706–12. [18] Abello L, Bochu B, Gaskov A, Koudryavtseva S, Lucazeau G, Roumyantseva M. Structural characterization of nanocrystalline SnO2 by x-ray and Raman spectroscopy. J. Solid State Chem. 1998;135:78–85. [19] Sensato FcR, Custódio R, Calatayud M, Beltrán A, Andrés J, Sambrano JR, et al. Periodic study on the structural and electronic properties of bulk, oxidized and reduced SnO2 surfaces and the interaction with O2. Surf. Sci. 2002;511:408–20.
Please cite this article as: Vijayarangamuthu K, Rath S. UV photoluminescence from nanocrystalline tin oxide synthesized by a one-step hydrothermal method. Mater Lett (2015), http://dx.doi.org/10.1016/j.matlet.2015.05.090i
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Contents lists available at ScienceDirect
Materials Letters journal homepage: www.elsevier.com/locate/matlet
UV photoluminescence from nanocrystalline tin oxide synthesized by a one-step hydrothermal method K. Vijayarangamuthu a,b,n, Shyama Rath a,c,n a
Department of Physics and Astrophysics, University of Delhi, Delhi 110007, India Department of Environmental Engineering, Inha University, Incheon 402-751, Republic of Korea c Department of Physics, Chulalongkorn University, Bangkok 10330, Thailand b
art ic l e i nf o
a b s t r a c t
Article history: Received 22 April 2015 Received in revised form 18 May 2015 Accepted 19 May 2015
Highly crystalline SnO2 nanocrystals with good size and shape uniformity were synthesized by a hydrothermal process. The highlight of this study is the observation of a sharp UV photoluminescence (PL) at 3.42 eV and a simultaneous absence of the broad defect-related visible PL emission. The PL emission is understood in the context of crystallinity, size/surface effects and oxygen vacancies as supported by the Raman spectra. The favorable structural and optical properties suggest their scope for UV light-emitting Q2 applications. & 2015 Elsevier B.V. All rights reserved.
Keywords: Tin oxide Hydrothermal Photoluminescence UV emission Raman
1. Introduction The large direct bandgap ( 3.6 eV) and a high exciton binding energy (130 meV) of SnO2 are favorable for room-temperature UV applications. However, the dipole-forbidden nature of its direct bandgap alongwith a commonly observed broad and intense deeplevel-defect-related visible emission restrict and overwhelm the band-edge emission. A modification of the electronic band structure, for example, by nanostructuring, could render the forbidden transition optically active [1–9]. In this respect, the hydrothermal wet synthesis method enables an excellent control over the size, shape and crystallinity [10–12]. However, optical studies have been limited and the UV photoluminescence (PL) was either absent, weak or broad [5,13]. The objective of our work is to exploit the advantages of hydrothermal method and we demonstrate morphologically uniform nanostructures with a sharp UV PL and a reduced concentration of defects.
used as the starting precursors without any further purification. A typical synthesis consists of dissolving 2.5 g of SnCl4 5H2O and 1.25 g of NaOH in a mixture containing equal volume of distilled water and ethylenediamine to form a slurry-like white precipitated solution. After 10 min of stirring, the solution was transferred into a teflon-lined stainless steel autoclave, which was maintained at 150 °C for 24 h and cooled naturally to room temperature. The product was centrifuged, filtered out, rinsed with alcohol and deionized water several times to remove impurities. The final product was dried at 100 °C for 60 min. The high-resolution x-ray diffraction (XRD) patterns were recorded with a Bruker D8 Advance x-ray diffractometer with a Cu Kα source (λ ¼1.5418 Å). Transmission electron microscopy (TEM) images were taken with a TECHNAI G2 300 kV instrument. MicroRaman measurements were performed using an in-Via Renishaw micro-Raman system with a 514.5 nm excitation. Low laser powers were used to avoid sample heating effects. The PL spectra were measured with a Horiba Jobin Yvon Fluorolog fluorescence spectrometer using a xenon lamp as the excitation source.
2. Experimental section SnCl4 5H2O and NaOH purchased from Sigma-Aldrich were n
Corresponding authors at: Department of Physics and Astrophysics, University of Delhi, Delhi 110007, India. E-mail addresses: [email protected] (K. Vijayarangamuthu), [email protected] (S. Rath).
3. Result and discussion The high-resolution XRD pattern of the synthesized SnO2 nanocrystals is shown in Fig. 1a. All the diffraction peaks could be indexed to the tetragonal rutile structure of SnO2 (JCPDS: 770448). The positions from JCPDS are also shown in the same figure
http://dx.doi.org/10.1016/j.matlet.2015.05.090 0167-577X/& 2015 Elsevier B.V. All rights reserved.
Please cite this article as: Vijayarangamuthu K, Rath S. UV photoluminescence from nanocrystalline tin oxide synthesized by a one-step hydrothermal method. Mater Lett (2015), http://dx.doi.org/10.1016/j.matlet.2015.05.090i
67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99
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K. Vijayarangamuthu, S. Rath / Materials Letters ∎ (∎∎∎∎) ∎∎∎–∎∎∎
for comparison. The lattice constants a and c calculated from the peaks of the (101) and (211) planes were 4.743 and 3.204 Å respectively, and match well with reported values. The sharp and intense peaks indicate good crystallinity. The high intensity along the (101) phase implies a horizontal growth direction of the elongated tetragonal structure. The average crystallite size was calculated to be around 10 nm using the Debye–Scherrer formula. Fig. 2(a and b) shows typical TEM images of the as-synthesized SnO2 nanoparticles. Uniformly shaped elongated structures with widths of around 7 nm are observed. The high-resolution TEM image (Fig. 2c) revealed a d-spacing corresponding to the (101) and (110) lattice planes of tetragonal SnO2 crystal (JCPDS: 770448). The continuous ring pattern with intense white dots in the
Fig. 1. (a) XRD pattern of hydrothermal SnO2 nanocrystals. The vertical red lines correspond to JCPDS card no: 77-0448.
Fig. 3. (a) Raman spectrum of hydrothermal SnO2 nanocrystals. (b) And (c) deconvolution of the Raman spectrum between 275 cm 1 and 375 cm 1, and 535 cm 1 and 700 cm 1 respectively.
Fig. 2. (a), (b) TEM images. (c) HR-TEM image with lattices spacing, and (d) selected-area-electron-diffraction pattern of SnO2 nanocrystals.
Please cite this article as: Vijayarangamuthu K, Rath S. UV photoluminescence from nanocrystalline tin oxide synthesized by a one-step hydrothermal method. Mater Lett (2015), http://dx.doi.org/10.1016/j.matlet.2015.05.090i
67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132
K. Vijayarangamuthu, S. Rath / Materials Letters ∎ (∎∎∎∎) ∎∎∎–∎∎∎
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Fig. 4. PL spectrum of SnO2 nano-crystalline powder: excited with (a) 300 nm. Inset: is the amplified spectra in the 450–800 nm range. (b) 280, 290, and 300 nm.
selected-area-electron-diffraction (SAED) pattern (Fig. 2d) indicates the highly crystalline nature. The lattice spacing between the fringes match with the lattice spacing values of the (101), (110), (211), and (112) planes observed in the XRD pattern. The microscopic structure is further investigated by Raman spectroscopy. SnO2, with six atoms in its unit cell, has 18 vibrational modes in the first Brillouin zone. The A1g, B1g, B2g and Eg are Raman active [14] while the Eu modes are IR active and Ramansilent. Additional modes due to size restriction, vacancies, surface defects have also been reported [15] and which can be correlated to the light-emitting properties. Fig. 3a illustrates the room temperature micro-Raman spectra of the as-synthesized SnO2 nanostructures and their peak assignments are tabulated in Table S1. The Raman modes at 628 (A1g), 771 (B2g), and 476 cm 1 (Eg) confirm the crystalline and tetragonal structure. The broad mode observed between 260 and 370 cm 1 can be deconvoluted into three modes at 286, 307 and 337 cm 1 Fig. 3b. The mode at 307 cm 1 is related to a surface defect in small-sized particles [16]. The modes at 250, 286 and 337 are the Eu modes activated due to the small particle size and a destruction of the k wavevector selection rule [17,18]. The deconvolution of the broad structure between 540 and 700 cm 1 (Fig. 3c) shows a S1 mode at 576 cm 1 correlated to the presence of in-plane oxygen vacancies (OVs) [15], a A1g mode at 628 cm 1, and a fourth Eu mode at 605 cm 1. An annealing leads to a disappearance of the size-related Raman modes (Fig S1) and a blue-shift in the peak position of A1g mode to 632 cm 1 due to increase in the particle size and transformation to bulk. Fig. 4a shows the room temperature PL emission of SnO2 nanocrystals excited with 300 nm. Two distinct UV emissions are observed: one at around 362 nm (3.42 eV) with a FWHM of 7.3 nm, which is considerably sharper than that reported in previous studies [3,13]. Its energy is about 0.58 eV lower than the bandgap obtained from UV measurements and about 0.38 eV lower than that estimated from quantum confinement models (Supplementary information S2). It is therefore energetically too far to be assigned to near-band edge effects or excitonic effects. This radiative transition is assigned to the donor–acceptor-pair (DAP) recombination [2,3,8] with the donor defect associated with an oxygen vacancy. Its position is independent of excitation wavelength as shown in Fig. 4b. The second PL emission occurs at 383 nm (3.23 eV). Its position and intensity on the other hand, vary monotonically with a change in the excitation wavelength. It shifts to 395 (3.13 eV) and 408 nm (3.03 eV) for excitation wavelengths of 280 and 290 nm respectively. The in-plane OV and surface defects, whose presence is supported by the Raman modes at 576 and 307 cm 1 are responsible for this emission and their role in the PL properties were shown by density functional theory
calculations [19]. The different excitation wavelength dependence of the two PL peaks indicates their different origin. Finally, along with UV emission, the near-complete absence of the defect-related visible emission is a notable feature indicating a significantly low defect concentration. Its extent, as seen in Fig. 4a, is restricted only to the 660 –780 nm spectral range rather than the much broader visible emission generally reported. Its intensity is insignificant as compared to the UV emission. This emission is due to a small quantity of lattice oxygen vacancies supported by electron paramagnetic resonance studies (Fig S3) and whose complete elimination is unlikely in metal-oxide thin films and nanostructures.
4. Conclusions Highly crystalline SnO2 nanostructures, with uniformity in size and shape, were synthesized by a simple hydrothermal method. A sharp UV PL is observed due to a combination of crystallinity and small sizes. The visible emission is of negligible intensity and limited to a narrow spectral range. The light emission properties are correlated to the structural aspects investigated by Raman spectroscopy. The favorable structural and PL properties indicate the efficacy of the synthesis process and the feasibility of nanocrystalline SnO2 for UV light emitting applications.
Acknowledgment This work was supported by grants from CARS Project 05/P264/09-10 of Defence Research Development Organization, Delhi University R&D Grant, and Nanomission project of Department of Science and Technology, India. KV acknowledges Council of Scientific and Industrial Research, India for a senior research fellowship.
Appendix A. Supplementary Information Supplementary data associated with this article can be found in the online version at http://dx.doi.org/10.1016/j.matlet.2015.05. 090.
References [1] Li Y, Yin W, Deng R, Chen R, Chen J, Yan Q, et al. Realizing a SnO2-based ultraviolet light-emitting diode via breaking the dipole-forbidden rule. NPG
Please cite this article as: Vijayarangamuthu K, Rath S. UV photoluminescence from nanocrystalline tin oxide synthesized by a one-step hydrothermal method. Mater Lett (2015), http://dx.doi.org/10.1016/j.matlet.2015.05.090i
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K. Vijayarangamuthu, S. Rath / Materials Letters ∎ (∎∎∎∎) ∎∎∎–∎∎∎
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Please cite this article as: Vijayarangamuthu K, Rath S. UV photoluminescence from nanocrystalline tin oxide synthesized by a one-step hydrothermal method. Mater Lett (2015), http://dx.doi.org/10.1016/j.matlet.2015.05.090i
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