Numerical model for the prediction of interfacial effect of ZnO/TCO on the performance of dye-sensitized solar cells (original) (raw)
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Theoretical modeling of TiO< sub> 2/TCO interfacial effect on dye-sensitized solar cell performance
Solar Energy Materials and Solar Cells, 2006
A theoretical model based on an integration of both Schottky barrier model and electron diffusion differential model was developed to determine the TiO2/TCO interfacial effect on the current–voltage (J–V) characteristics of a dye-sensitized solar cell (DSSC). The thermionic-emission theory was appropriately applied to describe the electron transfer at the TiO2/TCO interface. A parametric analysis was conducted to study how the photoelectric outputs varied with multiple independent variables, such as Schottky barrier height (φbφb) and temperature. It was found that the variation of the maximum DSSC power output (Pmax) was insignificant when φbφb varied at a low value; however, an increase in φbφb exceeding a critical value caused an apparent decrease in the maximum DSSC power output. The theoretical results were quantitatively compared and agreed very well with published theoretical results. The experimental data from literature were found to agree well with the present theoretical results, qualitatively validating the present model. The theoretical model can be applied to facilitate selection of suitable TCO material in DSSC design to avoid the adverse TiO2/TCO interfacial effect.
Nanostructured ZnO electrodes for dye-sensitized solar cell applications
Journal of Photochemistry and Photobiology A: Chemistry, 2002
Dye-sensitized photoelectrochemical solar cells constitute a promising candidate in the search for cost-effective and environment-friendly solar cells. The most extensively studied, and to date the most efficient systems are based on titanium dioxide. In this paper, the possibilities to use nanostructured ZnO electrodes in photoelectrochemical solar cells are investigated. Various experimental techniques (e.g. infrared, photoelectron, femtosecond and nanosecond laser spectroscopies, laser flash induced photocurrent transient measurements, twoand three-electrode photoelectrochemical measurements) show that the thermodynamics, kinetics and charge transport properties are comparable for ZnO and TiO 2. The preparation techniques of ZnO provide more possibilities of varying the particle size and shape compared to TiO 2. However, the dye-sensitization process is more complex in case of ZnO and care needs to be taken to achieve an optimal performance of the solar cell.
Scientific Review Dye Sensitized Solar Cells Incorporated with Tio 2-ZnO Nanoparticles
2017
The escalated and savage consumption of conventional sources of energy are leading to forecasted energy and environmental crises [1]. Solar Energy emerged as feasible alternative to confront the major environmental problems that result from the uncontrolled use of fossil resource in energy generation because "More energy from sunlight strikes Earth in 1 hour than all of the energy consumed by humans in an entire year" [2]. In 1991, Professor Grätzel reported a new low cost chemical solar cell by the successful combination of nanostructured electrode and efficient charge injecting dye, known as Grätzel cell or dye-sensitized solar cell which falls under the third generation photovoltaic cells [3]. In dye sensitized solar cells (DSSCs), dye molecules adsorbed on the oxide play a role of ""antenna"" for photon capturing. For this reason, accompanying with the development of DSSCs, organic dyes have been intensively studied with a focus on increasing the extinction coefficient and extending the optical absorption spectrum [4-10]. However, a major problem confronting these cells is the low efficiency of conversion. In optimizing the device performance and stability of DSSC, several research efforts have been expended on manipulating the corresponding architecture involving inorganic and organic systems as well as various interfaces so as to enhance the cell performance [11-14]. In general, ZnO nanoparticles based DSSCs shows low photoelectrochemical performance as compared to commercial TiO 2 based DSSCs [15]. Some of the limiting factor for this is insufficient attachment of dyes with the nanoparticles, formation of aggregation between the nanoparticles up on film formation, low injection rate, low regeneration of electron, and formation of Zn 2+ /dye complex. The formation of Zn 2+ /dye complex can agglomerate which comes from dissolution of the nanostructured film to form a thick covering layer instead of a monolayer, and is therefore inactive for electron injection which also limit the cell performance. This study proposed simple design strategies for realizing how to improve photovoltaic properties of the cell by coating on top of a TiO 2 semiconductor a layer of ZnO with different thickness. The PV performance of the formed DSSCs were investigated systematically. The conversion efficiency was increased from 0.0030 % to 0.0064 % for DSSC with 2 SILAR cycles which produces the best performance.
The Journal of Physical Chemistry C, 2007
Nanocrystalline particles of ZnO and TiO 2 of approximately equal size (∼15 nm) were used to prepare mesoporous electrodes for dye-sensitized solar cells. Electron transport in the solar cells was studied using intensity-modulated photocurrent spectroscopy and revealed very similar results for ZnO and TiO 2 . Apparent activation energies for electron transport in nanostructured ZnO of e0.1 eV were calculated from the temperature dependence of transport times under short-circuit conditions. The lifetime of electrons in the nanostructured semiconductors was evaluated from open-circuit voltage decay and intensity-modulated photovoltage spectroscopy. Significantly longer lifetimes were obtained with ZnO. Despite the reduced recombination, ZnO-based solar cells performed worse than TiO 2 cells, which was attributed to a lower electron injection efficiency from excited dye molecules and/or a lower dye regeneration efficiency. The internal voltage in the nanostructured ZnO film under short-circuit conditions was about 0.23 V lower than the opencircuit potential at the same light intensity. Results may be explained using a multiple trapping model, but as electrons are usually only shallowly trapped in ZnO, an alternative view is presented. If there is significant doping of the ZnO, resulting band bending in the nanocrystals will form energy barriers for electron transport and recombination that can explain the observed properties.
A Comparative Study on Optoelectronic Properties of Dye-sensitized Solar Cells using TiO 2 -ZnO Photo anodes, 2024
In present study, dye-sensitized solar cells (DSSC) are fabricated using bare TiO 2, ZnO and TiO 2-ZnO nanocomposite via doctor's blade method with N719 sensitizer and platinum-free carbon deposited counter electrode. The ensued TiO 2-ZnO (1:1) composite films of photoanodes are characterized with UV-Vis Spectroscopy to investigate the band gaps of bare TiO 2 , ZnO and their composite, in the range of 3.21-3.31 eV. SEM studies are performed to analyze the surface morphology wherein the TiO 2-ZnO composite photoelectrode, displayed additional prominent porosities than the bare TiO 2 /ZnO. The photo conversion efficiency of the cells based on TiO 2 , ZnO and their composite were observed as 1.08%, 0.98%, and 1.49%, respectively, which is higher for composite due to low series resistance, high optical absorption, high recombination resistance and longer lifetime as evaluated by impedance analysis. This strategy of using TiO 2-ZnO nanocomposite photoanode could pave the way for performance improvement in a cost-effective manner for DSSCs.
ZnO Nanostructures for Dye-Sensitized Solar Cells
Advanced Materials, 2009
This Review focuses on recent developments in the use of ZnO nanostructures for dye-sensitized solar cell (DSC) applications. It is shown that carefully designed and fabricated nanostructured ZnO films are advantageous for use as a DSC photoelectrode as they offer larger surface areas than bulk film material, direct electron pathways, or effective light-scattering centers, and, when combined with TiO 2 , produce a core-shell structure that reduces the combination rate. The limitations of ZnO-based DSCs are also discussed and several possible methods are proposed so as to expand the knowledge of ZnO to TiO 2 , motivating further improvement in the power-conversion efficiency of DSCs.
Photochemical performance of ZnO nanostructures in dye sensitized solar cells
Solid State Sciences, 2015
In this work, the photoconversion efficiencies of ZnO having diverse microstructures and structural defects have been investigated. A conversion efficiency of 1.38% was achieved for the DSSCs fabricated with as prepared ZnO nanorods having minimum vacancy defects and a favourable one dimensional directional pathway for electron conduction. The DSSCs fabricated with ZnO nanoparticles exhibited relatively low conversion efficiency of 1.004% probably due to multiple trapping/detrapping phenomena within the grain boundaries and ZnO flowers though exhibited a high dye adsorption capability exhibited the lowest conversion efficiency of 0.59% due to a high concentration of structural defects. Based on the experimental evidences, we believe that the type of defects and their concentrations are more important than shape in controlling the overall performance of ZnO based DSSCs.
Int. J. Electrochem. Sci, 2012
Interfacial properties at the photoelectrode of dye-sensitized solar cell (DSSC) play a vital role in determining its efficiency. This research examined the role of annealing temperature on the photoelectrode interfaces properties, and to find the annealing temperature that provides the highest overall solar cell efficiency. The electrical characteristics of the DSSC using ZnO nanoparticles photoelectrode annealed at different temperatures were studied using electrochemical impedance spectroscopy (EIS), and the corresponding IV ...
Photovoltaic Characteristics of ZnO Nanotube Dye-Sensitized Solar Cells and TiO 2 Nanostructure
The electrical transport in nanotube is extremely sensitive to local electrostatic environment due to their small size, large surface to volume ratio and high mobility. Among them, Oxide Zinc and Titanium are friendly for environment and promised materials. Dye sensitized solar cell (DSSC) is the only solar cell that can offer both the flexibility and transparency but its conversion efficiency is affected by physical and morphological parameters, like thickness, series resistance (Rs), ideality factor (n), saturation current (Is), shunt resistance (Rsh) and photocurrent (Iph) during elaboration as well as their normal use. This paper presents a simulation of photovoltaic characteristics of ZnO nanotube dye-sensitised solar cells and TiO2 nanostructure, by extracting the solar cell parameters which influence directly on solar cell output: conversion efficiency, fill factor, the short circuit photocurrent densities Isc and open-circuit voltage Voc. Furthermore, we review the relationship between geometry and output parameters.