Research Article Material Selection for Dye Sensitized ...downloads.hindawi.com/journals/jre/2014/506216.pdf · Research Article Material Selection for Dye Sensitized Solar Cells

Research ArticleMaterial Selection for Dye Sensitized Solar Cells Using MultipleAttribute Decision Making Approach

Sarita Baghel Ranjana Jha and Nikhil Jindal

School of Applied Sciences Netaji Subhas Institute of Technology Dwarka New Delhi 110078 India

Correspondence should be addressed to Sarita Baghel nsitsaritagmailcom

Received 8 August 2014 Revised 22 November 2014 Accepted 24 November 2014 Published 9 December 2014

Academic Editor Jing Shi

Copyright copy 2014 Sarita Baghel et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Dye sensitized solar cells (DSCs) provide a potential alternative to conventional p-n junction photovoltaic devices Thesemiconductor thin film plays a crucial role in the working of DSC This paper aims at formulating a process for the selectionof optimum semiconductor material for nanostructured thin film using multiple attribute decision making (MADM) approachVarious possible available semiconducting materials and their properties like band gap cost mobility rate of electron injectionand static dielectric constant are considered and MADM technique is applied to select the best suited material It was found thatout of all possible candidates titanium dioxide (TiO

2) is the best semiconductor material for application in DSC It was observed

that the proposed results are in good agreement with the experimental findings

1 Introduction

Rapid depletion of conventional resources is a major sourceof concern for the world today If not taken seriously soonthere shall be an inevitable energy crisis situation To preventsuch circumstances researchers today are forced to explorealternate energy sources Among available renewable energysources solar energy is the most promising and readilyavailable alternative Solar cells play a significant role inharnessing solar energy but due to numerous reasons wehave still not been able to effectively use the power of sunConventional silicon (Si) solar cells generally require complexvacuum processing and fairly high temperature conditionswhich makes them an expensive energy source [1ndash3] More-over their application is hampered by the lack of mechanicalflexibility Dye sensitized solar cells (DSCs) are attractive dueto their simple and low cost fabrication technique DSCs aredifferent from almost all other types of solar cells in theirfunctioning

DSCs are composed of a sensitizing dye adsorbed ona wide band nanostructured semiconductor film a redoxelectrolyte and a counter electrode consisting of a catalystFuture applications of DSCs depend upon the developmentand selection of suitable materials for their components so asto give the best performance

Among various components of DSC the nanocrystallineporous film electrode is most important as overall energyconversion of the cell is hugely affected by its morphologicaland electronic properties There are many materials thatare being used in the DSC while many more are beinginvestigated However each of these materials has certainmerits and limitations

Choosing the material of desired properties from largenumber of available materials is a tedious task A clearunderstanding of the functional needs of every componentand analysis of various important factors are required fordeveloping a comprehensive engineering design Consider-ing all the attributes at the same time in material selectionis a difficult job hence a systematic approach to materialselection process is required to screen and select the optimummaterial for device application

Recently Jenks and Gilmore [4] discussed design criteriaand numerical simulation for identifying optimal materialfor Quantum Dot Solar Cells Paul et al [5] and Sebitosi etal [6] outline material selection strategies for increasing theefficiency of heterojunction organic solar cell and enhancingperformance of small scale solar energy storage systems

Multiple criteria decision making (MCDM) methods arefrequently used to find solution of uncertainty problemsThese methods are classified into multiobjective decision

Hindawi Publishing CorporationJournal of Renewable EnergyVolume 2014 Article ID 506216 7 pageshttpdxdoiorg1011552014506216

2 Journal of Renewable Energy

Working electrode

Glasssubstrate

Glasssubstrate TCO

e

ee

CB

VBSemiconductor

film

LUMO

HOMODye

Electrolyte

Load

Pt

Counterelectrode

CB conduction bandVB valence bandPt Platinume electron

LUMO lowest unoccupied molecular orbitalHOMO highest occupied molecular orbitalTCO transparent conductive glass

Figure 1 A schematic description of dye sensitized solar cellworking

making (MODM) and multiple attribute decision making(MADM) techniques In MODM an alternative is optimizedon the basis of prioritized objectives while in MADMtechnique the selection of the best alternative is made fromthe available alternatives based on their prioritized attributes

Varieties of methods are developed based upon MADMapproach such as technique for order preference by simi-larity to ideal solution (TOPSIS) [7ndash9] VlseKriterijumskaOptimizacija I Kompromisno Resenje (VIKOR) [10ndash13]Elimination Et Choix Traduisant la REalite (ELECTRE) [14ndash16] Preference Ranking Organization Method for Enrich-ment Evaluation (PROMETHEE) [17] complex proportionalassessment (COPRAS) [18 19] and COPRAS-G [20] graphtheory and matrix approach [21] preference selection index(PSI) method [22] and linear assignment method [23]

These types of methods have earlier been reported in thefield of thin film solar cells (to find the best suited materialfor the active layer) polymer fuel cells and other solar energymaterials [24 25] For DSCs we for the first time report theapplication and findings of a material selection techniqueThis paper discusses a strategy for selecting a suitablematerialfor semiconductor film for DSC using MADM approach(TOPSIS) in order to enhance the device performance Thecore performance parameters for a semiconductor materialin DSC are band gap cost electron injection rate mobilityand static dielectric constant

2 Dye Sensitized Solar Cell Design

A DSC is basically a photoelectrochemical device in whicha dye sensitized nanostructured semiconducting film depos-ited on a transparent conductive glass (TCO) substrate formsa working electrode or photoelectrode Another platinumcoated glass substrate serves as counter electrode The inter-mediate space between these two electrodes is filled with aliquid or solid electrolyte (Figure 1)

The working electrode receives incident light which isabsorbed by the dye molecules adsorbed on the metaloxide semiconductor film The dye molecule gets excitedtransferring electron fromhighest occupiedmolecular orbital(HOMO) to lowest unoccupied molecular orbital (LUMO)The photogenerated electrons thenmove from dye moleculesto the semiconductor and then to the TCO The electronsare then collected by the counter electrode In a completecycle the oxidized dyemolecules are reduced by receiving theelectrons from the electrolyte at the same time electrolytegets regenerated by the electrons injected from the counterelectrode

There are certain parameters which define the perfor-mance of a solar cell Incident photon to current conversionefficiency (IPCE) is themost important factor which dependson light harvesting efficiency (LHE) of sensitizing dyemolecules charge injection efficiency at dye-semiconductorinterface and charge transport efficiency in nanostructuredfilm LHE is ratio of the incoming photons to that of absorbedphotons It depends on the amount of dye absorbed Chargeinjection efficiency is determined by many factors mainlyacceptor density in semiconductor and potential differencebetween conduction band of semiconductor and LUMO ofdyemolecule whereas charge transport efficiency depends onthe electron diffusion length To extract the photogeneratedelectrons the electrons should reach the TCO faster than therecombination process Thus charge recombination at thedevice interface strongly influences the IPCE [26]

According to a unidirectional electron transporting prin-ciple of DSC there exist four important interfaces in thisdeviceThose are the interfaces of FTOsemiconductor semi-conductordye dyeelectrolyte and the electrolytecounterelectrode [27] The properties of the semiconductor play adecisive role in the charge carrier kinetics at the interface andhence in the device performance [28]

3 Materials and Properties forPhotovoltaic Application

Ananostructured thin film of wide band gap semiconductingmaterial is used as an electron collecting material Thereare abundant semiconducting materials available but stillnot all of them are suitable for photovoltaic applicationsThere are certain constraints which need to be addressed inorder to choose best suited material to achieve commercialinterests Ideal semiconducting material for DSC applicationmust possess the following properties

(i) wide band gap(ii) high electron injection rate(iii) low cost(iv) high carrier concentration(v) low static dielectric constant(vi) high electron mobility

There are many candidate materials that are available forthe application in DSCs but only few possess the desired

Journal of Renewable Energy 3

properties as mentioned above Materials which are generallyused in the photoelectrode of DSC are titanium oxide (TiO

2)

zinc oxide (ZnO) tin oxide (SnO2) and indium (III) oxide

(In2O3) [29ndash32]These all are wide band gap semiconductors

having low cost and are easily available ZnO and SnO2par-

ticularly have fairly highmobilities which lead to fast electronconduction process The importance of metal oxide film isevident by the fact that the selection of materials for othercomponents of the cell is based upon their compatibilitieswith it The dye is selected based on its relative band edgepositions in sync with that of semiconductor used So whilechoosing the candidate materials for thin film it is importantto analyze their capability of working in tandem with thecommercially available set of dyesThe electron injection ratein the film largely depends upon this compatibility Also thecarrier concentration in the candidates should be high forbetter efficiencies

Thus there is a need to carefully select the material forthe fabrication of thin film as it plays a significant role inincreasing the active surface area as well as enhancing photonabsorption

So based on all the factors already mentioned before thefollowing materials were considered suitable candidates forthe preparation of mesoporous layer on FTO

(1) zinc oxide (ZnO)(2) titanium oxide (TiO

2)

(3) tin oxide (SnO2)

(4) indium (III) oxide (In2O3)

The major parameters that were considered for theiranalysis are electron injection time cost bulk mobility bandgap and effective mass static dielectric constant

4 Selection of Material

TOPSIS method has received lot of attention in the field ofmaterial selection Shanian and Savadogo [33] used TOPSISfor selecting the material for bipolar plates for polymerelectrolyte fuel cell Rao and Davim [34] introduced adecision making model based on both TOPSIS and analytichierarchy process (AHP) Chauhan and Vaish [35] alsoemployed TOPSIS and VIKOR to evaluate and asses theproperties of magnetic materials Chatterjee et al [18] usedVIKOR and ELECTRE methods to find the relative rankingof candidate materials by simultaneously considering theirrespective properties

Although ELECTREmethods generate good output theystill have certain drawbacks As the number of alternativesincreases the computational procedure becomes more com-plex and elaborate Also ELECTRE methods only providerank of each material but do not give any numerical value

The advantage of AHP over othermethods is its flexibilityand intuitiveness It supports group decision making bydetermining the geometric mean of the individual pairwisecomparisons But it has the disadvantage that the problemhasto be decomposed into a number of subsystems for pairwisecomparisons which is not always feasible

The VIKOR and TOPSIS method use different aggrega-tion functions and normalization process VIKOR methoduses linear normalization whereas TOPSIS method uses vec-tor normalization Finding the optimal point in the VIKOR isbased on the measure of closeness to positive ideal solutionTherefore it is more suitable in the circumstances in whichthe risk of the decisions is less important to the decisionmaker and maximum profit is the priority

TOPSIS is a good choice for material selection as it isa relatively more systematic process It is useful for bothqualitative and quantitative data It gives the output with anumerical value that provides the better understanding ofdifferences and similarities among the alternatives

TOPSIS method is employed to find the best alternativein the present work It was first proposed byHwang and Yoonin 1981 [36]

The methodology comprises calculating the Euclideandistance of the given alternative from the positive and thenegative ideal solution respectively The concept is that thebest possible alternative will be the one which is closest to thepositive ideal solution and the farthest from the negative idealsolution

The TOPSIS method consists of the following steps

Step 1 (construction of the normalized decision matrix) TheEuclidean length of a vector the element 119903

119894119895of the normalized

decision matrix 119877 is evaluated using the following transfor-mation

119903119894119895=

119883119894119895

radicsum119898

119894=1(119883119894119895)2

119895 = 1 2 119899 119894 = 1 2 119898 (1)

where 119903119894119895is the normalized preference measure of the 119894th

alternative ldquo119898rdquo is the number of alternatives and ldquo119899rdquo is thenumber of criteria

Step 2 (construction of the weighted normalized decisionmatrix) Multiply the columns of the normalized decisionmatrix with the set of weights 119882 = (119908

1 1199082 1199083 119908

119899) to

obtain weighted normalized decision matrix

119881 = 119877119882 = (

1199081sdot 11990311

1199082sdot 11990312

119908119899sdot 1199031119899

1199081sdot 11990321

1199082sdot 11990322

119908119899sdot 1199032119899

1199081sdot 1199031198981

1199082sdot 1199031198982

119908119899sdot 119903119898119899

) (2)

Step 3 (determination of the ideal and negative ideal solu-tions) The ideal solution and negative ideal solution valuesets are determined respectively as follows

119881+

1 119881+

2 119881

+

119899

= (Max119894

119881119894119895| 119869 isin 119870) (Min

119894

119881119894119895| 119869 isin 119870

1015840) | 119894 = 1 2 119898

119881minus

1 119881minus

2 119881

minus

119899

= (Min119894

119881119894119895| 119869 isin 119870) (Max

119894

119881119894119895| 119869 isin 119870

1015840) | 119894 = 1 2 119898

(3)


Table 1 Various properties of different possible semiconducting materials

Properties ZnO TiO2 SnO2 ln2O3 References

(1) Band gap (eV) 337 32 38 375 [40 41](2) Cost (Rs5 g) 3000 800 5000 7000 Slowast

(3) Electron injection time (times10minus12 s) 150 01 10 10 [39 40](4) Mobility (cm2 vminus1 sminus1) 200 1 250 160 [41ndash44](5) Effective mass (119898

119890

lowast) 03 70 03 03 [45 47](6) Dielectric constant (K) 80 173 250 89 [48]lowastSigma-Aldrich Co

where

119870 = 119895 = 1 2 3 119899 and

119895 is associated with benefit criteria

1198701015840= 119895 = 1 2 3 119899 and

119895 is associated with cost criteria

(4)

Step 4 (measurement of separation distances from idealand negative ideal solutions) Euclidean distances for eachalternative are respectively calculated as

119878+

119894=

119899

sum

119895=1

(119881119894119895minus 119881+

119895)

2

12

119894 = 1 2 119898

119878minus

119894=

119899

sum

119895=1

(119881119894119895minus 119881minus

119895)

2

12

119894 = 1 2 119898

(5)

Step 5 (calculation of the relative closeness to the ideasolution) The relative closeness to the ideal solution can bedefined as

119862119894=

119878minus

119894

119878+

119894+ 119878minus

119894

119894 = 1 2 119898 0 le 119862119894le 1 (6)

The higher the closeness means the better the rank

Step 6 (ranking of the preference order) The preferenceorder is ranked on the basis of the order of119862

119894 Hence the best

alternative is the one which is nearer to the ideal solution andfarther from the negative ideal solution

5 Results and Discussion

The properties of nanostructured film have significant influ-ence on the whole performance of DSC

Values of various properties of available materials havebeen enlisted in Table 1

The metal oxide semiconductors are being extensivelyused for solar energy conversion Nowotny [37] analysedfunctional properties of variousmetal oxides semiconductorsincluding TiO

2which are required for the fabrication of

high performance photosensitive devices Scaife [38] showedthat the photovoltaic performance of a solar cell depended

remarkably on the semiconductor material used They stud-ied the effect of mesoporous oxide semiconductor thin filmsproperties on solar cells

The transport of the injected electrons through nanos-tructured network is the most important process affectingthe device performance Near infrared absorption studiesconducted on nanocrystalline thin films made of differentmaterials but dyedwith sameRu-complex dye reveal differentinjection times [39] It has been observed that the transportkinetics is a function of electron density in the film whichis generally explained by trapping and detrapping rate in thestates in the band gap

Aroutiounian et al [40] investigated the properties ofdifferent metal oxide semiconductors such as band gap andmobility for photoelectrochemical conversion of solar energyIf the electron mobility in their bulk single crystal phasesis high then it is possible to achieve higher overall electronmobility in the respective nanostructured films which maythen reduce charge recombination loss at the electrolyteinterface which is composed of oxidized redox species henceenhancing device performance [41ndash44] A wide band gapsemiconductor with good carrier mobility is the secondessential requirements for the photoelectrode

The goal of any emerging solar cell technology is toachieve commercialisation and compete with other tech-nologies in photovoltaic market The cost of silicon pho-tovoltaic module has reduced from US$4Wminus1 in 2008 toonly US$125Wminus1 in 2011 with module efficiencies from 15to 20 On the other hand CdTe based thin film moduleshave achieved efficiencies of 14 at costs of US$050Wminus1 Inthe future solar cell market DSCs need to increase powerconversion efficiency with low cost fabrication proceduresand good stability Lowmodule cost ofDSCs can project themas attractive alternate energy source Therefore cost is thirdimportant factor influencing its commercial prospects

In addition to this the effective mass of conductionband electrons is another important parameter which definesthe electronic structure of conduction band of metal oxidesemiconductor film The available density of states is directlyrelated to the effective mass Higher density of states facil-itates faster electron injection [45ndash47] Electronic densityof states has more influence on the device performanceand bulk dielectric constant plays only a secondary role[48]

Considering all the above factors and conditions weightpriorities for respective parameter are evaluated


Using (1) we have the followingThe normalized matrix 119877 is

119877 = (

04761 03280 09955 05587 00427 00460

04520 00874 00006 00027 09969 09959

05368 05467 00663 06984 00427 00575

05298 07654 00663 04470 00498 00512

)

(7)

The weighted matrix119882 is

119882 = [5 4 6 3 2 1] (8)

The weighted normalized matrix 119881 is

119881 = (

23805 13120 59730 16761 00854 00460

22600 03496 00036 00081 19938 09959

26840 21868 03978 20952 00854 00575

26490 30616 03978 13410 00996 00512

)

(9)

The following values of separation variables were calculatedfrom the above matrix

119878+

1= 63616 119878

minus

1= 25999

119878+

2= 23317 119878

minus

2= 33687

119878+

3= 26781 119878

minus

3= 19872

119878+

4= 34158 119878

minus

4= 16910

(10)

The relative closeness to the ideal solution hence can be foundusing (6) The ranks are assigned based on their ldquoCrdquo valuesand are given by in Table 2 The larger the value of closenessthe better the rank

So from the ranks obtained we can conclude that out ofthe selected materials titanium dioxide (TiO

2) was found to

be the best suitable material for the photoelectrode of DSCfollowed by tin dioxide indium (III) oxide and zinc oxide

The evaluation of solar cell performance depends oncertain key parameters energy conversion efficiency andfill factor It has been reported that TiO

2based DSCs have

achieved 115 power conversion efficiency [49ndash52] whichis much higher than that of its other competitors SnO

2and

ZnO [53ndash56]Still conventional nanoparticulate SnO

2-DSCs have com-

paratively small conversion efficiencies of around 1-2 due tolow value of open circuit voltage (Voc) and fast recombina-tion process [57 58]

But the band gap of SnO2is much larger (119864

119892= 38 eV)

to be able to utilize the far ultraviolet portion of the lightspectrum SnO

2shall be the bestmaterial to be usedwith dyes

that absorb long wavelength sunlight Still a lot of research isin progress to develop such dyes [59ndash62]

Also it has higher electronic mobility and long termstability as compared to both single crystal TiO

2and ZnO

[63ndash66]To increase conversion efficiency various types of coating

materials on to SnO2surface such asAl

2O3MgOTiO

2 NiO

Y2O3 and ZnO have been investigated for the interfacial

Table 2 Solution of study based on TOPSIS method

Serialnumber Materials Solutions ldquo119862rdquo value Rank

1 Zinc oxide (ZnO) 1198621

02900 42 Titanium oxide (TiO2) 119862

205909 1

3 Tin oxide (SnO2) 1198623

04259 24 Indium (III) oxide (ln

2O3) 119862

403168 3

potential barrier [64ndash66] For instance a carefully controlledMgOSnO

2core-shell particle electrode achieved a high

efficiency of 72 by retarding the recombination process[65] These factors together make it a potential candidatefor application in DSC It has proved to be the second bestmaterial after TiO

2

Currently for ZnO-based DSCs efficiencies of up toabout 4ndash6 are being reported [63ndash66]

It is worth noting that photoelectrode properties forTiO2based DSCs are now approaching optimum theoretical

values while those for SnO2 In2O3 or ZnO still offer room

for improvement of several orders of magnitudeIt can be observed that the proposed result is in com-

pliance with the experimental findings hence justifying thevalidity of proposed study

6 Conclusions

Strategic evaluation of the properties of available semicon-ductor materials for DSCs was conducted by employing theMADM approach using Technique for Order Preference bySimilarity to Ideal Solution (TOPSIS) It was observed thattitanium dioxide (TiO

2) was the best suitedmaterial followed

by tin dioxide indium (III) oxide and zinc oxide Theseresults are also in agreement with experimental findingswhich supports the use of TiO

2in DSC in order to get high

performance device

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgment

Authors are grateful to Netaji Subhas Institute of TechnologyUniversity of Delhi for facilitating this work

References

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[2] M K Siddiki J Li D Galipeau and Q Qiao ldquoA review ofpolymer multijunction solar cellsrdquo Energy amp EnvironmentalScience vol 3 no 7 pp 867ndash883 2010

[3] T Xu and Q Qiao ldquoConjugated polymer-inorganic semicon-ductor hybrid solar cellsrdquo Energy amp Environmental Science vol4 no 8 pp 2700ndash2720 2011


[4] S Jenks and R Gilmore ldquoMaterial selection for the quantumdot intermediate band solar cellrdquo in Quantum Dot Solar Cellsvol 15 of Lecture Notes in Nanoscale Science and Technology pp135ndash166 Springer New York NY USA 2014

[5] H Paul C David and B P Rand ldquoStrategies for increasing theefficiency of heterojunction organic solar cells material selec-tion and device architecturerdquo Accounts of Chemical Researchvol 42 no 11 pp 1740ndash1747 2009

[6] A B Sebitosi ldquoPhase change material selection for small scalesolar energy storage systemrdquo Rwanda Journal C MathematicalSciences Engineering and Technology vol 23 2011

[7] C L Hwang and K Yoon Multiple Attribute Decision MakingMethods andApplication Survey vol 186 of LectureNotes in Eco-nomics and Mathematical Systems Springer Berlin Germany1981

[8] P Sen and J B Yang Multiple Criteria Decision Support inEngineering Design Springer New York NY USA 1998

[9] A S Milani A Shanian R Madoliat and J A Nemes ldquoTheeffect of normalization norms in multiple attribute decisionmaking models a case study in gear material selectionrdquo Struc-tural and Multidisciplinary Optimization vol 29 no 4 pp 312ndash318 2005

[10] T C Wang J L Liang and C Y Ho ldquoMulti-criteria decisionanalysis by using fuzzy VIKORrdquo in Proceedings of the Interna-tional Conference on Service Systems and Service Managementpp 25ndash27 2006

[11] S Opricovic and G-H Tzeng ldquoExtended VIKOR method incomparison with outranking methodsrdquo European Journal ofOperational Research vol 178 no 2 pp 514ndash529 2007

[12] S Datta and S Mahapatra ldquoComparative study on applicationof utility concept and VIKOR method for vendor selectionrdquoin Proceedings of the AIMS International Conference on Value-Based Management 2010

[13] J R San Cristobal ldquoMulti-criteria decision-making in theselection of a renewable energy project in spain the Vikormethodrdquo Renewable Energy vol 36 no 2 pp 498ndash502 2011

[14] R V Rao ldquoA decision making methodology for materialselection using an improved compromise ranking methodrdquoMaterials and Design vol 29 no 10 pp 1949ndash1954 2008

[15] A Shanian and O Savadogo ldquoAmaterial selection model basedon the concept ofmultiple attribute decisionmakingrdquoMaterialsand Design vol 27 no 4 pp 329ndash337 2006

[16] A Shanian and O Savadogo ldquoA non-compensatory compro-mised solution for material selection of bipolar plates for poly-mer electrolyte membrane fuel cell (PEMFC) using ELECTREIVrdquo Electrochimica Acta vol 51 no 25 pp 5307ndash5315 2006

[17] P Chatterjee and S Chakraborty ldquoMaterial selection usingpreferential ranking methodsrdquo Materials amp Design vol 35 pp384ndash393 2012

[18] P Chatterjee V M Athawale and S Chakraborty ldquoSelection ofmaterials using compromise ranking and outrankingmethodsrdquoMaterials and Design vol 30 no 10 pp 4043ndash4053 2009

[19] P Chatterjee V M Athawale and S Chakraborty ldquoMaterialsselection using complex proportional assessment and evalua-tion of mixed data methodsrdquoMaterials and Design vol 32 no2 pp 851ndash860 2011

[20] S R Maity P Chatterjee and S Chakraborty ldquoCutting toolmaterial selection using grey complex proportional assessmentmethodrdquoMaterials amp Design vol 36 pp 372ndash378 2012

[21] R V Rao ldquoA material selection model using graph theory andmatrix approachrdquoMaterials Science and Engineering A vol 431pp 48ndash55 2006

[22] K Maniya and M G Bhatt ldquoA selection of material using anovel type decision-makingmethod preference selection indexmethodrdquo Materials and Design vol 31 no 4 pp 1785ndash17892010

[23] A JahanM Y Ismail F Mustapha and SM Sapuan ldquoMaterialselection based on ordinal datardquo Materials and Design vol 31no 7 pp 3180ndash3187 2010

[24] N Gupta ldquoMaterial selection for thin-film solar cells usingmultiple attribute decision making approachrdquo Materials ampDesign vol 32 no 3 pp 1667ndash1671 2011

[25] A Jahan M Y Ismail S M Sapuan and F Mustapha ldquoMate-rial screening and choosing methodsmdasha reviewrdquo Materials ampDesign vol 31 no 2 pp 696ndash705 2010

[26] F Pichot and B A Gregg ldquoThe photovoltage -determiningmechanism in dye-sensitized solar cellsrdquoThe Journal of PhysicalChemistry B vol 104 no 1 pp 6ndash10 2000

[27] S Yanagida T Kitamura and Y Wada ldquoControl of chargetransfer and interface structures in nano-structured dye-sensitized solar cellrdquo in Nanotechnology and Nano-InterfaceControlled Electronic Devices pp 83ndash104 Elsevier AmsterdamThe Netherlands 2003

[28] M Nanu J Schoonman and A Goossens ldquoSolar-energy con-version in TiO

2CuInS

2nanocompositesrdquoAdvanced Functional

Materials vol 15 no 1 pp 95ndash100 2005[29] R Katoh A Furube T Yoshihara et al ldquoEfficiencies of electron

injection from excited n3 dye into nanocrystalline semiconduc-tor (ZrO

2 TiO

2 ZnO Nb

2O5 SnO

2 In2O3) filmsrdquo Journal of

Physical Chemistry B vol 108 no 15 pp 4818ndash4822 2004[30] J B Asbury E Hao Y Wang H N Ghosh and T Lian ldquoUltra-

fast electron transfer dynamics from molecular adsorbates tosemiconductor nanocrystalline thin filmsrdquo Journal of PhysicalChemistry B vol 105 no 20 pp 4545ndash4557 2001

[31] R W Fessenden and P V Kamat ldquoRate constants for chargeinjection from excited sensitizer into SnO

2 ZnO and TiO

2

semiconductor nanocrystallitesrdquoThe Journal of Physical Chem-istry vol 99 no 34 pp 12902ndash12906 1995

[32] Y Fukai Y Kondo SMori and E Suzuki ldquoHighly efficient dye-sensitized SnO

2solar cells having sufficient electron diffusion

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[33] A Shanian and O Savadogo ldquoTOPSIS multiple-criteria deci-sion support analysis for material selection of metallic bipolarplates for polymer electrolyte fuel cellrdquo Journal of Power Sourcesvol 159 no 2 pp 1095ndash1104 2006

[34] RV Rao and J PDavim ldquoAdecision-making frameworkmodelfor material selection using a combined multiple attributedecision-making methodrdquo International Journal of AdvancedManufacturing Technology vol 35 no 7-8 pp 751ndash760 2008

[35] A Chauhan and R Vaish ldquoMagnetic material selection usingmultiple attribute decision making approachrdquo Materials andDesign vol 36 pp 1ndash5 2012

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[38] D E Scaife ldquoOxide semiconductors in photoelectrochemicalconversion of solar energyrdquo Solar Energy vol 25 no 1 pp 41ndash54 1980


[39] A Furube M Murai S Watanabe K Hara R Katoh andM Tachiya ldquoNear-IR transient absorption study on ultra-fast electron-injection dynamics from a Ru-complex dye intonanocrystalline In

2O3thin films comparison with SnO

2 ZnO

and TiO2filmsrdquo Journal of Photochemistry and Photobiology A

Chemistry vol 182 no 3 pp 273ndash279 2006[40] V M Aroutiounian V M Arakelyan and G E Shahnazaryan

ldquoInvestigations of the metal-oxide semiconductors promisingfor photoelectrochemical conversion of solar energyrdquo SolarEnergy Materials and Solar Cells vol 89 no 2-3 pp 153ndash1632005

[41] D C Look D C Reynolds J R Sizelove et al ldquoElectricalproperties of bulk ZnOrdquo Solid State Communications vol 105no 6 pp 399ndash401 1998

[42] Z M Jarzebski and J P Marton ldquoPhysical properties of SnO2

materials II Electrical propertiesrdquo Journal of the Electrochem-istry Society vol 123 pp 299Cndash310C 1976

[43] D Jousse C Constantino and I Chambouleyron ldquoHighlyconductive and transparent amorphous tin oxiderdquo Journal ofApplied Physics vol 54 no 1 pp 431ndash434 1983

[44] E Shanthi V Dutta A Banerjee and K L Chopra ldquoElectricaland optical properties of undoped and antimony-doped tinoxide filmsrdquo Journal of Applied Physics vol 51 no 12 pp 6243ndash6251 1980

[45] X Ai N A Andersen J Guo and T Lian ldquoElectron injectiondynamics of Ru polypyridyl complexes on SnO

2nanocrystalline

thin filmsrdquoThe Journal of Physical Chemistry B vol 109 no 15pp 7088ndash7094 2005

[46] B Enright and D Fitzmaurice ldquoSpectroscopic determinationof electron and hole effective masses in a nanocrystallinesemiconductor filmrdquo Journal of Physical Chemistry vol 100 no3 pp 1027ndash1035 1996

[47] J Robertson ldquoElectronic structure of SnO2 GeO

2 PbO

2 TeO

2

and MgF2rdquo Journal of Physics C Solid State Physics vol 12 no

22 pp 4767ndash4776 1979[48] P Tiwana P Docampo M B Johnston H J Snaith and L M

Herz ldquoElectronmobility and injection dynamics inmesoporousZnO SnO

2 and TiO

2films used in dye-sensitized solar cellsrdquo

ACS Nano vol 5 no 6 pp 5158ndash5166 2011[49] M K Nazeeruddin F de Angelis S Fantacci et al ldquoCom-

bined experimental and DFT-TDDFT computational study ofphotoelectrochemical cell ruthenium sensitizersrdquo Journal of theAmerican Chemical Society vol 127 no 48 pp 16835ndash168472005

[50] F Gao Y Wang D Shi et al ldquoEnhance the optical absorp-tivity of nanocrystalline TiO

2film with high molar extinction

coefficient ruthenium sensitizers for high performance dye-sensitized solar cellsrdquo Journal of the American Chemical Societyvol 130 no 32 pp 10720ndash10728 2008

[51] C-Y Chen M Wang J-Y Li et al ldquoHighly efficient light-harvesting ruthenium sensitizer for thin-film dye-sensitizedsolar cellsrdquo ACS Nano vol 3 no 10 pp 3103ndash3109 2009

[52] Y Chiba A Islam Y Watanabe R Komiya N Koide and LHan ldquoDye-sensitized solar cells with conversion efficiency of111rdquo Japanese Journal of Applied Physics Part 2 Letters vol45 no 24ndash28 pp L638ndashL640 2006

[53] Q Zhang C S Dandeneau X Zhou and C Cao ldquoZnO nanos-tructures for dye-sensitized solar cellsrdquoAdvancedMaterials vol21 no 41 pp 4087ndash4108 2009

[54] K Keis E Magnusson H Lindstrom S-E Lindquist and AHagfeldt ldquoA 5 efficient photoelectrochemical solar cell based

on nanostructured ZnO electrodesrdquo Solar Energy Materials andSolar Cells vol 73 no 1 pp 51ndash58 2002

[55] W J Lee A Suzuki K Imaeda H Okada A Wakaharaand A Yoshida ldquoFabrication and characterization of eosin-Y-sensitized ZnO solar cellrdquo Japanese Journal of Applied Physicsvol 43 no 1 part 1 pp 152ndash155 2004

[56] Q Zhang T P Chou B Russo S A Jenekhe and G CaoldquoAggregation of ZnO nanocrystallites for high conversionefficiency in dye-sensitized solar cellsrdquo Angewandte ChemiemdashInternational Edition vol 47 no 13 pp 2402ndash2406 2008

[57] A N M Green E Palomares S A Haque J M Kroon andJ R Durrant ldquoCharge transport versus recombination in dye-sensitized solar cells employing nanocrystalline TiO

2and SnO

2

filmsrdquo Journal of Physical Chemistry B vol 109 no 25 pp12525ndash12533 2005

[58] N-G Park M G Kang K M Kim et al ldquoMorphological andphotoelectrochemical characterization of core-shell nanoparti-cle films for dye-sensitized solar cells Zn-O type shell on SnO

2

and TiO2coresrdquo Langmuir vol 20 no 10 pp 4246ndash4253 2004

[59] C Prasittichai and J T Hupp ldquoSurface modification ofSnO2photoelectrodes in dye-sensitized solar cells Significant

improvements in photovoltage via Al2O3atomic layer deposi-

tionrdquo Journal of Physical Chemistry Letters vol 1 no 10 pp 1611ndash1615 2010

[60] J B Xia F Y Li S M Yang and C H Huang ldquoCompositeelectrode SnO

2TiO2for dye-sensitized solar cellsrdquo Chinese

Chemical Letters vol 15 no 5 pp 619ndash622 2004[61] Z M Jarzebski and J P Marton ldquoPhysical properties of SnO

2

materialsrdquo Journal of the Electrochemical Society vol 123 pp299Cndash310C 1976

[62] M S Arnold P Avouris ZW Pan andZ LWang ldquoField-effecttransistors based on single semiconducting oxide nanobeltsrdquoThe Journal of Physical Chemistry B vol 107 no 3 pp 659ndash6632003

[63] E Hendry M Koeberg B OrsquoRegan and M Bonn ldquoLocal fieldeffects on electron transport in nanostructured TiO

2revealed

by terahertz spectroscopyrdquo Nano Letters vol 6 no 4 pp 755ndash759 2006

[64] A Kay andM Gratzel ldquoDye-sensitized core-shell nanocrystalsimproved efficiency of mesoporous tin oxide electrodes coatedwith a thin layer of an insulating oxiderdquo Chemistry of Materialsvol 14 no 7 pp 2930ndash2935 2002

[65] M K I Senevirathna P K D D P Pitigala E V A PremalalK Tennakone G R A Kumara and A Konno ldquoStability ofthe SnO

2MgO dye-sensitized photoelectrochemical solar cellrdquo

Solar Energy Materials and Solar Cells vol 91 no 6 pp 544ndash547 2007

[66] D Niinobe Y Makari T Kitamura Y Wada and S YanagidaldquoOrigin of enhancement in open-circuit voltage by adding ZnOto nanocrystalline SnO

2in dye-sensitized solar cellsrdquo Journal of

Physical Chemistry B vol 109 no 38 pp 17892ndash17900 2005

TribologyAdvances in

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

FuelsJournal of


Journal ofPetroleum Engineering


Industrial EngineeringJournal of


Power ElectronicsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Advances in

CombustionJournal of


Journal of


Renewable Energy

Submit your manuscripts athttpwwwhindawicom


StructuresJournal of


RotatingMachinery


EnergyJournal of


Hindawi Publishing Corporation httpwwwhindawicom

Journal ofEngineeringVolume 2014

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

International Journal ofPhotoenergy


Nuclear InstallationsScience and Technology of


Solar EnergyJournal of


Wind EnergyJournal of


Nuclear EnergyInternational Journal of


High Energy PhysicsAdvances in

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014


Working electrode

Glasssubstrate

Glasssubstrate TCO

e

ee

CB

VBSemiconductor

film

LUMO

HOMODye

Electrolyte

Load

Pt

Counterelectrode

CB conduction bandVB valence bandPt Platinume electron

LUMO lowest unoccupied molecular orbitalHOMO highest occupied molecular orbitalTCO transparent conductive glass

Figure 1 A schematic description of dye sensitized solar cellworking

making (MODM) and multiple attribute decision making(MADM) techniques In MODM an alternative is optimizedon the basis of prioritized objectives while in MADMtechnique the selection of the best alternative is made fromthe available alternatives based on their prioritized attributes

Varieties of methods are developed based upon MADMapproach such as technique for order preference by simi-larity to ideal solution (TOPSIS) [7ndash9] VlseKriterijumskaOptimizacija I Kompromisno Resenje (VIKOR) [10ndash13]Elimination Et Choix Traduisant la REalite (ELECTRE) [14ndash16] Preference Ranking Organization Method for Enrich-ment Evaluation (PROMETHEE) [17] complex proportionalassessment (COPRAS) [18 19] and COPRAS-G [20] graphtheory and matrix approach [21] preference selection index(PSI) method [22] and linear assignment method [23]

These types of methods have earlier been reported in thefield of thin film solar cells (to find the best suited materialfor the active layer) polymer fuel cells and other solar energymaterials [24 25] For DSCs we for the first time report theapplication and findings of a material selection techniqueThis paper discusses a strategy for selecting a suitablematerialfor semiconductor film for DSC using MADM approach(TOPSIS) in order to enhance the device performance Thecore performance parameters for a semiconductor materialin DSC are band gap cost electron injection rate mobilityand static dielectric constant

2 Dye Sensitized Solar Cell Design

A DSC is basically a photoelectrochemical device in whicha dye sensitized nanostructured semiconducting film depos-ited on a transparent conductive glass (TCO) substrate formsa working electrode or photoelectrode Another platinumcoated glass substrate serves as counter electrode The inter-mediate space between these two electrodes is filled with aliquid or solid electrolyte (Figure 1)

The working electrode receives incident light which isabsorbed by the dye molecules adsorbed on the metaloxide semiconductor film The dye molecule gets excitedtransferring electron fromhighest occupiedmolecular orbital(HOMO) to lowest unoccupied molecular orbital (LUMO)The photogenerated electrons thenmove from dye moleculesto the semiconductor and then to the TCO The electronsare then collected by the counter electrode In a completecycle the oxidized dyemolecules are reduced by receiving theelectrons from the electrolyte at the same time electrolytegets regenerated by the electrons injected from the counterelectrode

There are certain parameters which define the perfor-mance of a solar cell Incident photon to current conversionefficiency (IPCE) is themost important factor which dependson light harvesting efficiency (LHE) of sensitizing dyemolecules charge injection efficiency at dye-semiconductorinterface and charge transport efficiency in nanostructuredfilm LHE is ratio of the incoming photons to that of absorbedphotons It depends on the amount of dye absorbed Chargeinjection efficiency is determined by many factors mainlyacceptor density in semiconductor and potential differencebetween conduction band of semiconductor and LUMO ofdyemolecule whereas charge transport efficiency depends onthe electron diffusion length To extract the photogeneratedelectrons the electrons should reach the TCO faster than therecombination process Thus charge recombination at thedevice interface strongly influences the IPCE [26]

According to a unidirectional electron transporting prin-ciple of DSC there exist four important interfaces in thisdeviceThose are the interfaces of FTOsemiconductor semi-conductordye dyeelectrolyte and the electrolytecounterelectrode [27] The properties of the semiconductor play adecisive role in the charge carrier kinetics at the interface andhence in the device performance [28]

3 Materials and Properties forPhotovoltaic Application

Ananostructured thin film of wide band gap semiconductingmaterial is used as an electron collecting material Thereare abundant semiconducting materials available but stillnot all of them are suitable for photovoltaic applicationsThere are certain constraints which need to be addressed inorder to choose best suited material to achieve commercialinterests Ideal semiconducting material for DSC applicationmust possess the following properties

(i) wide band gap(ii) high electron injection rate(iii) low cost(iv) high carrier concentration(v) low static dielectric constant(vi) high electron mobility

There are many candidate materials that are available forthe application in DSCs but only few possess the desired



2)








2)
















119903119894119895=

119883119894119895

radicsum119898

119894=1(119883119894119895)2

119895 = 1 2 119899 119894 = 1 2 119898 (1)




1 1199082 1199083 119908

119899) to


119881 = 119877119882 = (

1199081sdot 11990311

1199082sdot 11990312

119908119899sdot 1199031119899

1199081sdot 11990321

1199082sdot 11990322

119908119899sdot 1199032119899

1199081sdot 1199031198981

1199082sdot 1199031198982

119908119899sdot 119903119898119899

) (2)


119881+

1 119881+

2 119881

+

119899

= (Max119894

119881119894119895| 119869 isin 119870) (Min

119894

119881119894119895| 119869 isin 119870

1015840) | 119894 = 1 2 119898

119881minus

1 119881minus

2 119881

minus

119899

= (Min119894

119881119894119895| 119869 isin 119870) (Max

119894

119881119894119895| 119869 isin 119870

1015840) | 119894 = 1 2 119898

(3)






119890


where

119870 = 119895 = 1 2 3 119899 and


1198701015840= 119895 = 1 2 3 119899 and


(4)


119878+

119894=

119899

sum

119895=1

(119881119894119895minus 119881+

119895)

2

12

119894 = 1 2 119898

119878minus

119894=

119899

sum

119895=1

(119881119894119895minus 119881minus

119895)

2

12

119894 = 1 2 119898

(5)


119862119894=

119878minus

119894

119878+

119894+ 119878minus

119894

119894 = 1 2 119898 0 le 119862119894le 1 (6)



















119877 = (

04761 03280 09955 05587 00427 00460

04520 00874 00006 00027 09969 09959

05368 05467 00663 06984 00427 00575

05298 07654 00663 04470 00498 00512

)

(7)


119882 = [5 4 6 3 2 1] (8)


119881 = (

23805 13120 59730 16761 00854 00460

22600 03496 00036 00081 19938 09959

26840 21868 03978 20952 00854 00575

26490 30616 03978 13410 00996 00512

)

(9)


119878+

1= 63616 119878

minus

1= 25999

119878+

2= 23317 119878

minus

2= 33687

119878+

3= 26781 119878

minus

3= 19872

119878+

4= 34158 119878

minus

4= 16910

(10)



2) was found to



2based DSCs have


2and


2-DSCs have com-



119892= 38 eV)





2and ZnO



2O3MgOTiO

2 NiO






205909 1



2O3) 119862

403168 3




2






6 Conclusions





performance device



Acknowledgment


References






























2CuInS




2 TiO

2 ZnO Nb

2O5 SnO





2 ZnO and TiO

2














2 ZnO










2nanocrystalline




2 PbO

2 TeO

2




2 and TiO















2and SnO

2



2








2




2revealed













FuelsJournal of







Advances in



Journal of


Renewable Energy





RotatingMachinery


EnergyJournal of



















2)








2)
















119903119894119895=

119883119894119895

radicsum119898

119894=1(119883119894119895)2

119895 = 1 2 119899 119894 = 1 2 119898 (1)




1 1199082 1199083 119908

119899) to


119881 = 119877119882 = (

1199081sdot 11990311

1199082sdot 11990312

119908119899sdot 1199031119899

1199081sdot 11990321

1199082sdot 11990322

119908119899sdot 1199032119899

1199081sdot 1199031198981

1199082sdot 1199031198982

119908119899sdot 119903119898119899

) (2)


119881+

1 119881+

2 119881

+

119899

= (Max119894

119881119894119895| 119869 isin 119870) (Min

119894

119881119894119895| 119869 isin 119870

1015840) | 119894 = 1 2 119898

119881minus

1 119881minus

2 119881

minus

119899

= (Min119894

119881119894119895| 119869 isin 119870) (Max

119894

119881119894119895| 119869 isin 119870

1015840) | 119894 = 1 2 119898

(3)






119890


where

119870 = 119895 = 1 2 3 119899 and


1198701015840= 119895 = 1 2 3 119899 and


(4)


119878+

119894=

119899

sum

119895=1

(119881119894119895minus 119881+

119895)

2

12

119894 = 1 2 119898

119878minus

119894=

119899

sum

119895=1

(119881119894119895minus 119881minus

119895)

2

12

119894 = 1 2 119898

(5)


119862119894=

119878minus

119894

119878+

119894+ 119878minus

119894

119894 = 1 2 119898 0 le 119862119894le 1 (6)



















119877 = (

04761 03280 09955 05587 00427 00460

04520 00874 00006 00027 09969 09959

05368 05467 00663 06984 00427 00575

05298 07654 00663 04470 00498 00512

)

(7)


119882 = [5 4 6 3 2 1] (8)


119881 = (

23805 13120 59730 16761 00854 00460

22600 03496 00036 00081 19938 09959

26840 21868 03978 20952 00854 00575

26490 30616 03978 13410 00996 00512

)

(9)


119878+

1= 63616 119878

minus

1= 25999

119878+

2= 23317 119878

minus

2= 33687

119878+

3= 26781 119878

minus

3= 19872

119878+

4= 34158 119878

minus

4= 16910

(10)



2) was found to



2based DSCs have


2and


2-DSCs have com-



119892= 38 eV)





2and ZnO



2O3MgOTiO

2 NiO






205909 1



2O3) 119862

403168 3




2






6 Conclusions





performance device



Acknowledgment


References






























2CuInS




2 TiO

2 ZnO Nb

2O5 SnO





2 ZnO and TiO

2














2 ZnO










2nanocrystalline




2 PbO

2 TeO

2




2 and TiO















2and SnO

2



2








2




2revealed













FuelsJournal of







Advances in



Journal of


Renewable Energy





RotatingMachinery


EnergyJournal of






















119890


where

119870 = 119895 = 1 2 3 119899 and


1198701015840= 119895 = 1 2 3 119899 and


(4)


119878+

119894=

119899

sum

119895=1

(119881119894119895minus 119881+

119895)

2

12

119894 = 1 2 119898

119878minus

119894=

119899

sum

119895=1

(119881119894119895minus 119881minus

119895)

2

12

119894 = 1 2 119898

(5)


119862119894=

119878minus

119894

119878+

119894+ 119878minus

119894

119894 = 1 2 119898 0 le 119862119894le 1 (6)



















119877 = (

04761 03280 09955 05587 00427 00460

04520 00874 00006 00027 09969 09959

05368 05467 00663 06984 00427 00575

05298 07654 00663 04470 00498 00512

)

(7)


119882 = [5 4 6 3 2 1] (8)


119881 = (

23805 13120 59730 16761 00854 00460

22600 03496 00036 00081 19938 09959

26840 21868 03978 20952 00854 00575

26490 30616 03978 13410 00996 00512

)

(9)


119878+

1= 63616 119878

minus

1= 25999

119878+

2= 23317 119878

minus

2= 33687

119878+

3= 26781 119878

minus

3= 19872

119878+

4= 34158 119878

minus

4= 16910

(10)



2) was found to



2based DSCs have


2and


2-DSCs have com-



119892= 38 eV)





2and ZnO



2O3MgOTiO

2 NiO






205909 1



2O3) 119862

403168 3




2






6 Conclusions





performance device



Acknowledgment


References






























2CuInS




2 TiO

2 ZnO Nb

2O5 SnO





2 ZnO and TiO

2














2 ZnO










2nanocrystalline




2 PbO

2 TeO

2




2 and TiO















2and SnO

2



2








2




2revealed













FuelsJournal of







Advances in



Journal of


Renewable Energy





RotatingMachinery


EnergyJournal of



















119877 = (

04761 03280 09955 05587 00427 00460

04520 00874 00006 00027 09969 09959

05368 05467 00663 06984 00427 00575

05298 07654 00663 04470 00498 00512

)

(7)


119882 = [5 4 6 3 2 1] (8)


119881 = (

23805 13120 59730 16761 00854 00460

22600 03496 00036 00081 19938 09959

26840 21868 03978 20952 00854 00575

26490 30616 03978 13410 00996 00512

)

(9)


119878+

1= 63616 119878

minus

1= 25999

119878+

2= 23317 119878

minus

2= 33687

119878+

3= 26781 119878

minus

3= 19872

119878+

4= 34158 119878

minus

4= 16910

(10)



2) was found to



2based DSCs have


2and


2-DSCs have com-



119892= 38 eV)





2and ZnO



2O3MgOTiO

2 NiO






205909 1



2O3) 119862

403168 3




2






6 Conclusions





performance device



Acknowledgment


References






























2CuInS




2 TiO

2 ZnO Nb

2O5 SnO





2 ZnO and TiO

2














2 ZnO










2nanocrystalline




2 PbO

2 TeO

2




2 and TiO















2and SnO

2



2








2




2revealed













FuelsJournal of







Advances in



Journal of


Renewable Energy





RotatingMachinery


EnergyJournal of











































2CuInS




2 TiO

2 ZnO Nb

2O5 SnO





2 ZnO and TiO

2














2 ZnO










2nanocrystalline




2 PbO

2 TeO

2




2 and TiO















2and SnO

2



2








2




2revealed













FuelsJournal of







Advances in



Journal of


Renewable Energy





RotatingMachinery


EnergyJournal of




















2 ZnO










2nanocrystalline




2 PbO

2 TeO

2




2 and TiO















2and SnO

2



2








2




2revealed













FuelsJournal of







Advances in



Journal of


Renewable Energy





RotatingMachinery


EnergyJournal of





















FuelsJournal of







Advances in



Journal of


Renewable Energy





RotatingMachinery


EnergyJournal of

















Documents

Research Article Material Selection for Dye Sensitized ...downloads.hindawi.com/journals/jre/2014/506216.pdf · Research Article Material Selection for Dye Sensitized Solar Cells