C.O. Sreekala

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.

Studies on polymer based counter electrodes for DSSC application

Dye-sensitized solar cell provides a precisely and economically reliable alternate concept of present day energy crisis. DSSC have emerged as the next generation of photovoltaic devices, offering several advantages, including moderate light to conversion efficiency, low cost, flexible and easy fabrication. DSSC have many components that have to be optimized, are a mesoporous titania layer adsorbed with dye molecule, electrolyte and a counter electrode. In this work we focused on making polymer based counter electrodes for DSSC application. We made counter electrodes with PEDOT:PSS incorporated with MWCNTs and compared with the standard platinum counter electrode. The optical transmittance of the counter electrodes is studied to examine their possibility for use as transparent counter electrodes for DSSC application.

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.

Photovoltaic studies of PbSe quantum dot based solar cells

The PbSe quantum dots are synthesized by organometallic synthesis method. The current-voltage (J-V) characteristics of TiO2/PbSe quantum dot (QD) solar cells from a Schottky junction that forms at the back metal electrode opposing the desirable diode formed between the TiO2 and PbSe QD layers. We study the J-V curves of the FTO/TiO2/PbSe/Au device under dark and illuminated condition. The FESEM image of the device cross section is taken and analyzed. We also study the band structure of the device.

Heterojunction TiO 2 /PbS quantum dot solar cells

PbS Quantum dots are promising materials for photovoltaic applications due to their absorption in the NIR region. In this work monodisperse lead sulfide quantum dots are synthesized using colloidal procedures using oleic acid and oleylamine as the stabilizing agents and 1-octadecene as the non-coordinating solvent. Heterojunction solar cell with FTO/TiO2/PbS/Au structure is fabricated and characterized. The current-voltage characteristics shows the roll-over effect that refers to the saturation of photocurrent in forward bias and crossover effect which occurs when the light and dark J-V curves intersect.

Synthesis and characterization of Lead Selenide quantum dots for photovoltaic application

Lead Selenide (PbSe) quantum dots (QDs) with absorption in the NIR region are synthesized in a non-coordinating solvent, octadecene by organometallic synthesis procedure. The high resolution transmission electron microscopy (HRTEM) analysis demonstrated spherical shape and monodispered nature of PbSe Quantum dots. Absorption spectrum demonstrates that the QDs show absorbance in the near infrared (NIR) region. The synthesized QDs give a good dispersion in n-hexane.

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.

Photovoltaic parameters of DSSCs using natural dyes with TiO 2 nanopowder and nanofiber as photoanodes: A comparative study

Dye-sensitized solar cells (DSCs) are currently attracting academic and commercial interest as regenerative low-cost alternatives to conventional solar cell devices. Researchers are focusing to facilitate for producing a low cost, eco-friendly and more efficient dye sensitized solar cells. Natural dye sensitized solar cells are a promising class of photovoltaic cells with the capacity of generating green energy at low production cost since no expensive equipment is required in their fabrication. In the present work we discuss the effect of Photoanodes sensitized with natural dyes Lawsone and Alizarin. We compared the efficiency of the devices fabricated with TiO2 nanofibers and nanopowder as photoanodes using these natural dyes. It is found that when we used nano fibers instead of nano powder as photo anode the dye adsorption on the TiO2 surface increases. This helps to harvest more photons and increases photocurrent density. As a result there is a significant increase in short circuit current density and conversion efficiency.

Escalating the performance of perovskite solar cell via electrospun TiO 2 nanofibers

A Perovskite solar cell is a type of solar cell which includes a perovskite structured compound, most commonly a hybrid organic-inorganic lead or tin halide based material, as the light harvesting active layer. In this work solar cell based on titanium dioxide (TiO2) thin film, sensitized with methyl ammonium lead iodide (CH3NH3PbI3) perovskite are prepared. Thin films were grown on fluorine doped tin oxide (FTO) glass plate. TiO2 is working as the anode and a noble metal will work as the cathode. A perovskite is more efficient than a dye in sensitizing a solar cell. It will act both as hole transporting material and sensitizer. It is found that the efficiency of solar cell devices using these materials shows considerable change in Voc and Jsc by the use of TiO2 nanofibers as the anode material.