Research Article
Energy Transfer Kinetics and Luminescence in Nd3+/Yb3+Co-Doped Lead-Borate Glasses at 800 nm Excitation
Renuka Bairagi,
Ghizal Firdous Ansari*
,
Mohd Yaseen Lone,
Sandeep Kumar Sharma
Issue:
Volume 10, Issue 1, June 2024
Pages:
1-6
Received:
24 April 2024
Accepted:
16 May 2024
Published:
30 May 2024
Abstract: Nd3+ and Nd3+/Yb3+ ion-doped lead-borate glasses were created. For the thermal studies of sample such as glass transition temperature, crystallization temperature and, melting temperature Tm, differential scanning calorimetry (DSC) is done. The X-ray diffraction is used to justify the glassy nature of the samples. UV-VIS-IR of the prepared samples is carried for the studies of absorption bands available in Nd3+ and Nd3+/Yb3+ ion-doped lead-borate glasses. For the studies of fluorescence spectra and energy transfer mechanism the samples were excited at 800nm and spectra is recorded. The Nd3+ glasses exhibited strong NIR emission at 1mol% concentration at 903, 1068, and 1348 nm upon pumping at 800 nm. These transitions were labelled as 4F3/2→4I9/2, 4F3/2→4I11/2, and 4F3/2→4I13/2. Interpretation is given to the effects of multiphonon, cross-relaxation, and OH- group on Nd3+ emission that causes photoluminescence quenching above 1.0mol% Nd3+. Through the co-doping of Nd3+ ion (1mol%) and Yb3+ ion (1mol%) concentrations, the sensitising impact of Nd3+ emission on Yb3+ luminescence is examined. The significant spectrum of Yb3+ absorption and Nd3+ emission, photoluminescence characteristics, has supported the likelihood of energy-transfer (ET) between these ions. The findings show that the Neodymium ion (4F3/2)→ytterbium ion (4F5/2) energy-transfer process is of a non-radiative type controlled by phonon-assisted electric dipole-dipole interaction.
Abstract: Nd3+ and Nd3+/Yb3+ ion-doped lead-borate glasses were created. For the thermal studies of sample such as glass transition temperature, crystallization temperature and, melting temperature Tm, differential scanning calorimetry (DSC) is done. The X-ray diffraction is used to justify the glassy nature of the samples. UV-VIS-IR of the prepared samples ...
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Research Article
Influence of Graphene on Sheet Resistivity and Urbach Enery of Nano TiO2 for DSSC Electrode
Geoffrey Gitonga Riungu*,
Simon Waweru Mugo,
James Mbiyu Ngaruyia,
Leonard Gitu
Issue:
Volume 10, Issue 1, June 2024
Pages:
7-12
Received:
15 June 2024
Accepted:
1 July 2024
Published:
23 July 2024
Abstract: Importance of renewable energy cannot be over emphasized. Titanium IV oxide (TiO2) is the most suitable semiconductor for dye sensitized solar cell (DSSC) due to its chemical stability, non toxicity and excellent optoelectronic properties. In this research TiO2 is coated on graphene to enhance its charge transport aiming to reduce recombination which is a main set back in DSSCs. undestanding graphene- TiO2 contact is therefore essential for DSSC application. TiO2 thin films were deposited on single layer graphene (SLG) as well as on flourine tin oxide (FTO) using doctor blading technique. The films were annealed at rates of 2°C /min and 1°C/min up to a temperature of 450°C followed by sintering at this temperature for 30 minutes. Four point probe SRM-232 was used to measure sheet resistance of the samples. The film thickness were obtained from transmittance using pointwise unconstrained minimization approximation (PUMA). UV –VIS spectrophotometer was employed to measure transmittance. Resistivity of TiO2 on both FTO and Graphene were of order 10-4 Ωcm. However, TiO2 annealed on graphene matrix exhibited a slightly lower resistivity 5.6 x10-4 Ωcm as compared to 6.0x10-4 Ωcm on FTO. Optical transmittance on visible region was lower for TiO2 on FTO than on SLG, 71.48% and 80.11% respectively. Urbach energy (Eu) for weak absorption region decreased with annealing rate. Urbach energies for 1°C/min TiO2 on FTO and SLG were 361 meV and 261meV respectively. This was used to account for decrease of disoders of films due to annealing. A striking relation between sheet resistivity and urbach was reported suggesting SLG as a suitable candidate for photoanode of a DSSC.
Abstract: Importance of renewable energy cannot be over emphasized. Titanium IV oxide (TiO2) is the most suitable semiconductor for dye sensitized solar cell (DSSC) due to its chemical stability, non toxicity and excellent optoelectronic properties. In this research TiO2 is coated on graphene to enhance its charge transport aiming to reduce recombination whi...
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