K.S. Sreelatha

The VALUE @ Amrita Virtual Labs Project: Using Web Technology to Provide Virtual Laboratory Access to Students

In response to the Indian Ministry of Human Resource Development (MHRD) National Mission on Education through Information and Communication Technology (NME-ICT) Initiative, the Virtual and Accessible Laboratories Universalizing Education (VALUE @ Amrita) Virtual Labs Project was initiated to provide laboratory-learning experiences to college and university students across India who may not have access to adequate laboratory facilities or equipment. These virtual laboratories require only a broadband Internet connection and standard web browser. Amrita Vishwa Vidyapeetham University (Amrita University) is part of a consortium of twelve institutions building over two hundred virtual labs covering nine key disciplines in science and engineering. This National Mission project hopes to reach out to Indias millions of engineering and science students at both undergraduate and postgraduate levels. The Virtual Labs Project is providing virtual laboratory experiments that directly support the All India Council for Technical Education (AICTE) and the University Grants Commission (UGC) model curricula for engineering and sciences undergraduate and postgraduate programs.

Dye Sensitized Solar Cell using Natural Dyes as Chromophores - Review

The molecular dye is an essential component of the Dye sensitized solar cell (DSSC), and improvements in efficiency over the last 15 years have been achieved by tailoring the optoelectronic properties of the dye. The most successful dyes are based on ruthenium bipyridyl compounds, which are characterized by a large absorption coefficient in the visible part of the solar spectrum, good adsorption properties, excellent stability, and efficient electron injection. However, ruthenium-based compounds are relatively expensive, and organic dyes with similar characteristics and even higher absorption coefficients have recently been reported; solar cells with efficiencies of up to 9% have been reported. Organic dyes with a higher absorption coefficient could translate into thinner nanostructured metal oxide films, which would be advantageous for charge transport both in the metal oxide and in the permeating phase, allowing for the use of higher viscosity materials such as ionic liquids, solid electrolytes or hole conductors. Organic dyes used in the DSSC often bear a resemblance to dyes found in plants, fruits, and other natural products, and several dye-sensitized solar cells with natural dyes have been reported. This paper gives an over-view of the recent works in DSSC using the natural dyes as chromophores.

Enhanced photovoltaic performance of the dye sensitized solar cell using natural dyes with surface modification of the photoanode

The efficiency of the best Dye sensitized solar cell is primarily depends on the good light harvesting property of the photo anode. Present study uses Lawsone (2 hydroxy [1, -naphthoquinone), the natural dye and compare the performance of photo anode in bare TiO2 and with nanoporous CaCO3 coated TiO2. As compared to bare TiO2, the surface area of nanoporous CaCO3-coated TiO2 increases, consequently, a better amount of dye adsorption occurs. The coating of CaCO3 increases the impedance at TiO2/dye/electrolyte interface and affect lifetime of the photoelectrons. Due to this reasons the short circuit current Jsc, open-circuit voltage (Voc), and fill factor (FF) increases. Thereby, the energy conversion efficiency of the solar cell is improved.

Organic Bulk Heterojunction Solar Cell Based on Rosebengal: ncTiO2 and Parameter Extraction by Simulation

In bulk heterojunction solar cells, the donor and acceptor materials are intimately blended throughout the bulk, so that the excitons generated will reach the interface within their lifetime. In this work, Rosebengal (RB) is used as the donor material and nanocrystalline Titanium dioxide (nc TiO2) as the acceptor material. Devices with device structure ITO/RB:TiO2/Ag are prepared and their optical and electrical properties are compared at different temperatures. Optical absorption spectroscopic analysis shows that the absorption of Rose bengal ranges from 650-800 nm corresponding to a band gap of 1.98 eV. Cyclic voltametric analysis, and photo voltaic properties are analysed. Using simulation, the dark current parameters such as ideality factor (n), mobility (µ) potential barrier (φb) and carrier concentration are extracted and tabulated.

Device stability study of dye sensitized solar cells incorporated with MWCNTs

Dye-sensitized solar cells (DSSC) or Gratzel cells have attracted extensive academic and commercial interest during the last 20 years due to their potential for low cost solar energy conversion. Dye-sensitized solar cell works on the principle similar to photosynthesis. The major parts of dye-sensitized solar cells are working electrode or photo electrode, dye, electrolyte and counter electrode. Each key components have its own importance for the conversion visible light into electricity. This work highlights studies on stability of device fabricated with different counter electrodes. The photovoltaic parameters of the prepared DSSCs were compared and tabulated. It is found that the DSSC with functionalized MWCNTs as counter electrode shows the best efficiency.