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Experimental observation of spatially resolved photo-luminescence intensity distribution in dual mode upconverting nanorod bundles

View Article: PubMed Central - PubMed

ABSTRACT

A novel method for demonstration of photoluminescence intensity distribution in upconverting nanorod bundles using confocal microscopy is reported. Herein, a strategy for the synthesis of highly luminescent dual mode upconverting/downshift Y1.94O3:Ho3+0.02/Yb3+0.04 nanorod bundles by a facile hydrothermal route has been introduced. These luminescent nanorod bundles exhibit strong green emission at 549 nm upon excitations at 449 nm and 980 nm with quantum efficiencies of ~6.3% and ~1.1%, respectively. The TEM/HRTEM results confirm that these bundles are composed of several individual nanorods with diameter of ~100 nm and length in the range of 1–3 μm. Furthermore, two dimensional spatially resolved photoluminescence intensity distribution study has been carried out using confocal photoluminescence microscope throughout the nanorod bundles. This study provides a new direction for the potential use of such emerging dual mode nanorod bundles as photon sources for next generation flat panel optical display devices, bio-medical applications, luminescent security ink and enhanced energy harvesting in photovoltaic applications.

No MeSH data available.


(a) PL mapping of slanted positioned Y1.94O3:Ho3+0.02/Yb3+0.04 nanorod bundle. (b) PL mapping along the length of slant positioned Y1.94O3:Ho3+0.02/Yb3+0.04 nanorod bundle, inset shows the intensity distribution from position A to B. (c) PL mapping along the diameter of slant positioned Y1.94O3:Ho3+0.02/Yb3+0.04 nanorod bundle, inset shows the intensity distribution from position A to B. (d) PL mapping vertically positioned Y1.94O3:Ho3+0.02/Yb3+0.04 nanorod bundle. (e) PL mapping along the length of vertically positioned Y1.94O3:Ho3+0.02/Yb3+0.04 nanorod bundle, inset shows the intensity distribution from position A to B. (f) PL mapping along the diameter of vertically positioned Y1.94O3:Ho3+0.02/Yb3+0.04 nanorod bundle, inset shows the intensity distribution from position A to B.
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f4: (a) PL mapping of slanted positioned Y1.94O3:Ho3+0.02/Yb3+0.04 nanorod bundle. (b) PL mapping along the length of slant positioned Y1.94O3:Ho3+0.02/Yb3+0.04 nanorod bundle, inset shows the intensity distribution from position A to B. (c) PL mapping along the diameter of slant positioned Y1.94O3:Ho3+0.02/Yb3+0.04 nanorod bundle, inset shows the intensity distribution from position A to B. (d) PL mapping vertically positioned Y1.94O3:Ho3+0.02/Yb3+0.04 nanorod bundle. (e) PL mapping along the length of vertically positioned Y1.94O3:Ho3+0.02/Yb3+0.04 nanorod bundle, inset shows the intensity distribution from position A to B. (f) PL mapping along the diameter of vertically positioned Y1.94O3:Ho3+0.02/Yb3+0.04 nanorod bundle, inset shows the intensity distribution from position A to B.

Mentions: The 2D spatially resolved PL mapping was performed to explore the PL intensity distribution in nanorod bundles. The use of confocal microscope for PL imaging allowed mapping the spatial variation in the PL intensity of nanorod bundles using an excitation wavelength of 980 nm. The schematic diagram and theoretical concept of confocal microscope is shown in Figure S11 (see Supplementary Information). Figure 2a represents the fluorescent image of nanorod bundles at 980 nm excitation wavelength and Figure S12 (see Supplementary Information) represents the corresponding optical image of nanorod bundles. The fluorescent image clearly demonstrates strong green emission throughout the bunch of Y1.94O3:Ho3+0.02/Yb3+0.04 nanorod bundles at different places. Further, PL mapping was performed at the same location from where the fluorescent image was taken (Fig. 2b) to explore the 2D spatial distribution of PL intensity on the surface of Y1.94O3:Ho3+0.02/Yb3+0.04 nanorod bundles. It is evident from Fig. 2b that the PL intensity distribution is not uniform. This is due to the fact that the topological surface of nanorod bundles are not uniform due to random selection of area and bunch of bundles being located at different heights. Furthermore, to explore a logistic behind observed non-uniform 2D PL intensity distribution of the surface of nanorod bundles, two different nanorod bundles with different profile heights are randomly selected. The PL mapping was performed and shown in Fig. 2c. The PL mapping result reveals that the intensity distribution is almost similar in two different nanorod bundles with different profile heights except the difference in PL intensity as shown in the insets of Fig. 2c (from A to B). In order to probe the precise 2D PL intensity distribution of the surface of isolated nanorod bundles another area of the sample where nanorod bundles are located individually either in horizontal or vertical position are selected. Figure 3a exhibits the optical image of isolated horizontal positioned single nanorod bundle. The inset of Fig. 3a represents fluorescent image of nanorod bundle showing strong green emission throughout the bundle (using excitation wavelength of 980 nm). Figure 3b exhibits the PL mapping image of isolated horizontal positioned single nanorod bundle. Figure 3c shows the PL intensity distribution along the length of nanorod bundle from one end to other end of the nanorod bundle, respectively (from A to B). The result reveals that the distribution is almost uniform (variation in PL intensity is ~0.1% in same order of magnitude) from position A to B in both the cases except the two broad peaks originating from the both edges of the bundle as shown in Fig. 3c. Usually, the PL intensity distribution appears uniform with naked eye in many cases but after investigation, did not show as expected, which can impact the optical display significantly and such issues can also be resolved through present probing method. Even <0.1% difference in same order of PL intensity can be also examine through this technique. Such observations are highly important in many cases such as flat penal display devices and optoelectronic devices. Similarly, the PL intensity distribution along the diameter of isolated bundles at three different selected positions; left, middle and right sides (marked from A to B) of isolated nanorod bundle are also investigated and result is shown in Fig. 3d–f. The result reveals the exact variation in PL intensity distributions at different places along the diameter of nanorod bundle. Furthermore, we also performed PL mapping of slanted and vertically positioned nanorod bundles and results are shown in Fig. 4a–f. The exact variations in PL intensity distribution have been shown in insets of Fig. 4a–f. However, the observed small variations in PL intensity distribution in nanorod bundles having different orientations are due to non-ideal alignment of nanorod in bundle shape. Hence, above PL mapping results justify its utility as a powerful tool to investigate the PL intensity distribution in luminescent materials.


Experimental observation of spatially resolved photo-luminescence intensity distribution in dual mode upconverting nanorod bundles
(a) PL mapping of slanted positioned Y1.94O3:Ho3+0.02/Yb3+0.04 nanorod bundle. (b) PL mapping along the length of slant positioned Y1.94O3:Ho3+0.02/Yb3+0.04 nanorod bundle, inset shows the intensity distribution from position A to B. (c) PL mapping along the diameter of slant positioned Y1.94O3:Ho3+0.02/Yb3+0.04 nanorod bundle, inset shows the intensity distribution from position A to B. (d) PL mapping vertically positioned Y1.94O3:Ho3+0.02/Yb3+0.04 nanorod bundle. (e) PL mapping along the length of vertically positioned Y1.94O3:Ho3+0.02/Yb3+0.04 nanorod bundle, inset shows the intensity distribution from position A to B. (f) PL mapping along the diameter of vertically positioned Y1.94O3:Ho3+0.02/Yb3+0.04 nanorod bundle, inset shows the intensity distribution from position A to B.
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f4: (a) PL mapping of slanted positioned Y1.94O3:Ho3+0.02/Yb3+0.04 nanorod bundle. (b) PL mapping along the length of slant positioned Y1.94O3:Ho3+0.02/Yb3+0.04 nanorod bundle, inset shows the intensity distribution from position A to B. (c) PL mapping along the diameter of slant positioned Y1.94O3:Ho3+0.02/Yb3+0.04 nanorod bundle, inset shows the intensity distribution from position A to B. (d) PL mapping vertically positioned Y1.94O3:Ho3+0.02/Yb3+0.04 nanorod bundle. (e) PL mapping along the length of vertically positioned Y1.94O3:Ho3+0.02/Yb3+0.04 nanorod bundle, inset shows the intensity distribution from position A to B. (f) PL mapping along the diameter of vertically positioned Y1.94O3:Ho3+0.02/Yb3+0.04 nanorod bundle, inset shows the intensity distribution from position A to B.
Mentions: The 2D spatially resolved PL mapping was performed to explore the PL intensity distribution in nanorod bundles. The use of confocal microscope for PL imaging allowed mapping the spatial variation in the PL intensity of nanorod bundles using an excitation wavelength of 980 nm. The schematic diagram and theoretical concept of confocal microscope is shown in Figure S11 (see Supplementary Information). Figure 2a represents the fluorescent image of nanorod bundles at 980 nm excitation wavelength and Figure S12 (see Supplementary Information) represents the corresponding optical image of nanorod bundles. The fluorescent image clearly demonstrates strong green emission throughout the bunch of Y1.94O3:Ho3+0.02/Yb3+0.04 nanorod bundles at different places. Further, PL mapping was performed at the same location from where the fluorescent image was taken (Fig. 2b) to explore the 2D spatial distribution of PL intensity on the surface of Y1.94O3:Ho3+0.02/Yb3+0.04 nanorod bundles. It is evident from Fig. 2b that the PL intensity distribution is not uniform. This is due to the fact that the topological surface of nanorod bundles are not uniform due to random selection of area and bunch of bundles being located at different heights. Furthermore, to explore a logistic behind observed non-uniform 2D PL intensity distribution of the surface of nanorod bundles, two different nanorod bundles with different profile heights are randomly selected. The PL mapping was performed and shown in Fig. 2c. The PL mapping result reveals that the intensity distribution is almost similar in two different nanorod bundles with different profile heights except the difference in PL intensity as shown in the insets of Fig. 2c (from A to B). In order to probe the precise 2D PL intensity distribution of the surface of isolated nanorod bundles another area of the sample where nanorod bundles are located individually either in horizontal or vertical position are selected. Figure 3a exhibits the optical image of isolated horizontal positioned single nanorod bundle. The inset of Fig. 3a represents fluorescent image of nanorod bundle showing strong green emission throughout the bundle (using excitation wavelength of 980 nm). Figure 3b exhibits the PL mapping image of isolated horizontal positioned single nanorod bundle. Figure 3c shows the PL intensity distribution along the length of nanorod bundle from one end to other end of the nanorod bundle, respectively (from A to B). The result reveals that the distribution is almost uniform (variation in PL intensity is ~0.1% in same order of magnitude) from position A to B in both the cases except the two broad peaks originating from the both edges of the bundle as shown in Fig. 3c. Usually, the PL intensity distribution appears uniform with naked eye in many cases but after investigation, did not show as expected, which can impact the optical display significantly and such issues can also be resolved through present probing method. Even <0.1% difference in same order of PL intensity can be also examine through this technique. Such observations are highly important in many cases such as flat penal display devices and optoelectronic devices. Similarly, the PL intensity distribution along the diameter of isolated bundles at three different selected positions; left, middle and right sides (marked from A to B) of isolated nanorod bundle are also investigated and result is shown in Fig. 3d–f. The result reveals the exact variation in PL intensity distributions at different places along the diameter of nanorod bundle. Furthermore, we also performed PL mapping of slanted and vertically positioned nanorod bundles and results are shown in Fig. 4a–f. The exact variations in PL intensity distribution have been shown in insets of Fig. 4a–f. However, the observed small variations in PL intensity distribution in nanorod bundles having different orientations are due to non-ideal alignment of nanorod in bundle shape. Hence, above PL mapping results justify its utility as a powerful tool to investigate the PL intensity distribution in luminescent materials.

View Article: PubMed Central - PubMed

ABSTRACT

A novel method for demonstration of photoluminescence intensity distribution in upconverting nanorod bundles using confocal microscopy is reported. Herein, a strategy for the synthesis of highly luminescent dual mode upconverting/downshift Y1.94O3:Ho3+0.02/Yb3+0.04 nanorod bundles by a facile hydrothermal route has been introduced. These luminescent nanorod bundles exhibit strong green emission at 549&thinsp;nm upon excitations at 449&thinsp;nm and 980&thinsp;nm with quantum efficiencies of ~6.3% and ~1.1%, respectively. The TEM/HRTEM results confirm that these bundles are composed of several individual nanorods with diameter of ~100&thinsp;nm and length in the range of 1&ndash;3&thinsp;&mu;m. Furthermore, two dimensional spatially resolved photoluminescence intensity distribution study has been carried out using confocal photoluminescence microscope throughout the nanorod bundles. This study provides a new direction for the potential use of such emerging dual mode nanorod bundles as photon sources for next generation flat panel optical display devices, bio-medical applications, luminescent security ink and enhanced energy harvesting in photovoltaic applications.

No MeSH data available.