Limits...
Biologically inspired band-edge laser action from semiconductor with dipole-forbidden band-gap transition.

Wang CS, Liau CS, Sun TM, Chen YC, Lin TY, Chen YF - Sci Rep (2015)

Bottom Line: In addition, a stunning laser action is further discovered in the albumen/SnO2 NWs composite system.More importantly, the giant oscillator strength of shallow defect states, which is served orders of magnitude larger than that of the free exciton, plays a decisive role.Our approach therefore shows that bio-materials exhibit a great potential in applications for novel light emitters, which may open up a new avenue for the development of bio-inspired optoelectronic devices.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, National Taiwan University, Taipei 106, Taiwan.

ABSTRACT
A new approach is proposed to light up band-edge stimulated emission arising from a semiconductor with dipole-forbidden band-gap transition. To illustrate our working principle, here we demonstrate the feasibility on the composite of SnO2 nanowires (NWs) and chicken albumen. SnO2 NWs, which merely emit visible defect emission, are observed to generate a strong ultraviolet fluorescence centered at 387 nm assisted by chicken albumen at room temperature. In addition, a stunning laser action is further discovered in the albumen/SnO2 NWs composite system. The underlying mechanism is interpreted in terms of the fluorescence resonance energy transfer (FRET) from the chicken albumen protein to SnO2 NWs. More importantly, the giant oscillator strength of shallow defect states, which is served orders of magnitude larger than that of the free exciton, plays a decisive role. Our approach therefore shows that bio-materials exhibit a great potential in applications for novel light emitters, which may open up a new avenue for the development of bio-inspired optoelectronic devices.

No MeSH data available.


(a) Scanning electron microscope (SEM) image of the as-grown pristine SnO2 nanowires (NWs). The inset shows a closer SEM image. (b) Photoluminescence of SnO2 NWs. (c) X-ray diffraction pattern of SnO2 NWs. (d) Raman scattering spectrum of SnO2 NWs.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4355669&req=5

f1: (a) Scanning electron microscope (SEM) image of the as-grown pristine SnO2 nanowires (NWs). The inset shows a closer SEM image. (b) Photoluminescence of SnO2 NWs. (c) X-ray diffraction pattern of SnO2 NWs. (d) Raman scattering spectrum of SnO2 NWs.

Mentions: Figure 1(a) shows the top view SEM image of the as-synthesized SnO2 NWs. It is observed that the nanowires are randomly assembled and closely packed. An inset of Fig. 1(a) reveals a closer view on SnO2 NWs. The average length is of about 10 μm, while the diameter is ranging between 70 nm and 150 nm. The XRD pattern of the as-prepared SnO2 NWs is shown in Fig. 1(c). It can be seen that all peaks are perfectly indexed to the tetragonal rutile SnO2. As additional evidence, a Raman scattering spectrum is shown in Fig. 1(d), in which the three peaks at 475, 630, 768 cm−1 correspond to the Eg, A1g, and B2g vibration modes, respectively. All these informations further confirm the existence of the as-grown SnO NWs. For the optical properties, a PL spectrum is first characterized as shown in Fig. 1(b). We can clearly see that only a broad orange emission peak located at 625 nm (2.0 eV) is observed, and no ultraviolet fluorescence can be detected. The detected visible light arising from SnO2 is generally believed to stem from the deep-trapped state, which is related to the oxygen vacancies (Ov) or tin interstitials (Sni)14. Figure 2 presents the PL spectra for both of the pristine SnO2 NWs and chicken albumen. The UV emission arising from albumen is centered at around 340 nm, and the FWHM is much narrower compared with that of the bare SnO2 NWs. It is found that the optical property for albumen is quite stable even under the UV laser pumping. At the beginning, the albumen was spin-coated on a cleaned glass substrate for the PL measurement. The first sample was then stored and preserved in a Petri dish at room temperature. More than our expectation, the PL can still be detected and shown to be stable even after 6 months. Based on these characteristics, albumen from chicken egg reveals one of its advantages as an excellent UV-emitting biomolecule. The inset of Fig. 2 illustrates the separation of egg white (albumen) and egg yolk. In addition to the fluorescence properties, the transmittance spectra of albumen with different spin-coating speed were also shown in Fig. 3. The film thicknesses are about 800 nm (1000 rpm) and 400 nm (5000 rpm), respectively. Both the albumen samples with different thickness show similar transmission properties which indicate good transparency from ultraviolet to visible range. The inset of Fig. 3 shows the topological AFM of the albumen surface, and the root mean square (RMS) roughness is 0.34 nm.


Biologically inspired band-edge laser action from semiconductor with dipole-forbidden band-gap transition.

Wang CS, Liau CS, Sun TM, Chen YC, Lin TY, Chen YF - Sci Rep (2015)

(a) Scanning electron microscope (SEM) image of the as-grown pristine SnO2 nanowires (NWs). The inset shows a closer SEM image. (b) Photoluminescence of SnO2 NWs. (c) X-ray diffraction pattern of SnO2 NWs. (d) Raman scattering spectrum of SnO2 NWs.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4355669&req=5

f1: (a) Scanning electron microscope (SEM) image of the as-grown pristine SnO2 nanowires (NWs). The inset shows a closer SEM image. (b) Photoluminescence of SnO2 NWs. (c) X-ray diffraction pattern of SnO2 NWs. (d) Raman scattering spectrum of SnO2 NWs.
Mentions: Figure 1(a) shows the top view SEM image of the as-synthesized SnO2 NWs. It is observed that the nanowires are randomly assembled and closely packed. An inset of Fig. 1(a) reveals a closer view on SnO2 NWs. The average length is of about 10 μm, while the diameter is ranging between 70 nm and 150 nm. The XRD pattern of the as-prepared SnO2 NWs is shown in Fig. 1(c). It can be seen that all peaks are perfectly indexed to the tetragonal rutile SnO2. As additional evidence, a Raman scattering spectrum is shown in Fig. 1(d), in which the three peaks at 475, 630, 768 cm−1 correspond to the Eg, A1g, and B2g vibration modes, respectively. All these informations further confirm the existence of the as-grown SnO NWs. For the optical properties, a PL spectrum is first characterized as shown in Fig. 1(b). We can clearly see that only a broad orange emission peak located at 625 nm (2.0 eV) is observed, and no ultraviolet fluorescence can be detected. The detected visible light arising from SnO2 is generally believed to stem from the deep-trapped state, which is related to the oxygen vacancies (Ov) or tin interstitials (Sni)14. Figure 2 presents the PL spectra for both of the pristine SnO2 NWs and chicken albumen. The UV emission arising from albumen is centered at around 340 nm, and the FWHM is much narrower compared with that of the bare SnO2 NWs. It is found that the optical property for albumen is quite stable even under the UV laser pumping. At the beginning, the albumen was spin-coated on a cleaned glass substrate for the PL measurement. The first sample was then stored and preserved in a Petri dish at room temperature. More than our expectation, the PL can still be detected and shown to be stable even after 6 months. Based on these characteristics, albumen from chicken egg reveals one of its advantages as an excellent UV-emitting biomolecule. The inset of Fig. 2 illustrates the separation of egg white (albumen) and egg yolk. In addition to the fluorescence properties, the transmittance spectra of albumen with different spin-coating speed were also shown in Fig. 3. The film thicknesses are about 800 nm (1000 rpm) and 400 nm (5000 rpm), respectively. Both the albumen samples with different thickness show similar transmission properties which indicate good transparency from ultraviolet to visible range. The inset of Fig. 3 shows the topological AFM of the albumen surface, and the root mean square (RMS) roughness is 0.34 nm.

Bottom Line: In addition, a stunning laser action is further discovered in the albumen/SnO2 NWs composite system.More importantly, the giant oscillator strength of shallow defect states, which is served orders of magnitude larger than that of the free exciton, plays a decisive role.Our approach therefore shows that bio-materials exhibit a great potential in applications for novel light emitters, which may open up a new avenue for the development of bio-inspired optoelectronic devices.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, National Taiwan University, Taipei 106, Taiwan.

ABSTRACT
A new approach is proposed to light up band-edge stimulated emission arising from a semiconductor with dipole-forbidden band-gap transition. To illustrate our working principle, here we demonstrate the feasibility on the composite of SnO2 nanowires (NWs) and chicken albumen. SnO2 NWs, which merely emit visible defect emission, are observed to generate a strong ultraviolet fluorescence centered at 387 nm assisted by chicken albumen at room temperature. In addition, a stunning laser action is further discovered in the albumen/SnO2 NWs composite system. The underlying mechanism is interpreted in terms of the fluorescence resonance energy transfer (FRET) from the chicken albumen protein to SnO2 NWs. More importantly, the giant oscillator strength of shallow defect states, which is served orders of magnitude larger than that of the free exciton, plays a decisive role. Our approach therefore shows that bio-materials exhibit a great potential in applications for novel light emitters, which may open up a new avenue for the development of bio-inspired optoelectronic devices.

No MeSH data available.