research article enhancing performance of sno -based...

Research ArticleEnhancing Performance of SnO2-Based Dye-Sensitized SolarCells Using ZnO Passivation Layer

W M N M B Wanninayake12 K Premaratne23 and R M G R Rajapakse24

1Department of Civil Engineering Faculty of Engineering University of Peradeniya 20400 Peradeniya Sri Lanka2Postgraduate Institute of Science University of Peradeniya 20400 Peradeniya Sri Lanka3Department of Physics Faculty of Science University of Peradeniya 20400 Peradeniya Sri Lanka4Department of Chemistry Faculty of Science University of Peradeniya 20400 Peradeniya Sri Lanka

Correspondence should be addressed to W M N M B Wanninayake mihirawanninayakegmailcom

Received 11 August 2016 Revised 6 September 2016 Accepted 8 September 2016

Academic Editor Yanfa Yan

Copyright copy 2016 W M N M B Wanninayake et al This is an open access article distributed under the Creative CommonsAttribution License which permits unrestricted use distribution and reproduction in any medium provided the original work isproperly cited

Although liquid electrolyte based dye-sensitized solar cells (DSCs) have shown higher photovoltaic performance in their classthey still suffer from some practical limitations such as solvent evaporation leakage and sealing imperfections These problemscan be circumvented to a certain extent by replacing the liquid electrolytes with quasi-solid-state electrolytes Even though SnO

2

shows high election mobility when compared to the semiconductor material commonly used in DSCs the cell performance ofSnO2-based DSCs is considerably low due to high electron recombination This recombination effect can be reduced through the

use of ultrathin coating layer of ZnO on SnO2nanoparticles surface ZnO-based DSCs also showed lower performance due to its

amphoteric nature which help dissolve in slightly acidic dye solution In this study the effect of the composite SnO2ZnO system

was investigated SnO2ZnO composite DSCs showed 100 and 38 increase of efficiency compared to the pure SnO

2-based and

ZnO-based devices respectively with the gel electrolyte consisting of LiI salt

1 Introduction

Dye-sensitized solar cells (DSCs) based on thin film na-nocrystalline high band gap semiconductor materials havereceived attention as an alternative to conventional single-crystal silicon solar cells owing to their low productioncost easy fabrication procedure and relatively high energy-conversion efficiency Since the early development of DSCsby Gratzel in 1991 considerable effort has been devoted toimproving their performance [1 2]This study focused on thedevelopment of the semiconductormaterial and electrolyte asthe efficiency of the DSCs depends on many factors such assemiconductor material sensitizer and electrolyte In DSCsTiO2is the most popular semiconductor material but it

shows some retarding effects due to its low electron mobilityand charge transport property which leads to increase of thedark current of the solar cell device and photocatalytic abilitywhich tends to degrade the dye molecules Therefore SnO

2

is employed in place of TiO2as it has sim250 cm2 Vminus1 sminus1 of

electronmobility [3 4]This property of SnO2will contribute

towards recombination through the surface trap levels ofSnO2nanoparticles There are two major recombination

processes present in DSCs One is regeneration of exciteddye molecules with the injected electrons The other iscombination of the injected electrons with the triiodide ionsin the electrolytes due to the back tunneling of injectedelectrons

In order to enhance the performance of the SnO2-based

solar cell device by reducing recombination effect one ofthe useful methods is applying the ZnO coating layer ontop of the SnO

2surface This ZnO layer also acts as a

passivation layer which will reduce the I3

minus ion recombinationwith the injected electron Since ZnO is a high band gapsemiconductor it is expected to act in a differentmanner thanthe high band gap insulating coating layers Kumara et alhave conducted a research based on composite SnO

2ZnO

system with liquid electrolytes and achieved an efficiency of49 As far as we are concerned this is the first time that the

Hindawi Publishing CorporationInternational Journal of PhotoenergyVolume 2016 Article ID 9087478 8 pageshttpdxdoiorg10115520169087478

2 International Journal of Photoenergy

performance and suitability of composite SnO2ZnOwith gel

polymer electrolytes are reported [5ndash8]Even though the use of gel polymer electrolytes sacrifices

the performance of DSCs to some extent due to low ionmobility it shows cohesive nature of solids and diffusivenature of liquids while showing good stability in outdoorapplications due to their promising properties such as ther-mal stability nontoxicity lower flammability and environ-mental friendliness Generally the diffusivity of triiodide ionsin gel based electrolytes lies in 10minus6 to 10minus7 cm2 sminus1 rangeElectrolytes based on organic solvents or ionic liquids canbe gelated or polymerized by dispersing suitable polymermaterials to obtain quasi-solid-state electrolytes Polymerbackbone in gel electrolyte medium will help the transportof ions and this ion conduction is called the Grotthussmechanism

There is a vast amount of literature available for theDSCs fabricated with polymer based gel electrolytes and theireffects on the performance of the device [9ndash20] In summarypolymethylhydrosiloxane poly(vinylidenefluoride-co-hexafluor-opropylene) (PVDFHFP) 3-methoxypropionitrile (MPN)24-di-O-dimethylbenzylidene-D-sorbitol (DMDBS) poly[di(ethylene glycol)-2-ethyl hexyl ether acrylate] (PDEA) poly(vinylpyridine-co-acrylonitrile) [P(VP-coAN)] poly(ethyl-ene oxide) (PEO) polyvinylpyridine hydroxystearic acidimidazole polymers polysaccharides poly(epichlorohydrin-co-ethylene oxide) and polyacrylonitrile (PAN) polymerswere used in the past few decades Also the other trendof gelatin mechanism is by the introduction of nanofillerssuch as TiO

2 Al2O3 fumed silica and many other inorganic

materials into the host liquid electrolytes Somehow thesetypes of polymer based gel electrolytes gave an efficiencyof about 7 The conductivities of the gel polymer basedelectrolytes mainly depended on the oligomer size or molec-ular weight and salts used in the gel polymer electrolyteLiI salt and PAN-based gel polymer [21] electrolytes aremost frequently used in fabrication of DSCs in addition tomixed salts based gel electrolytes [22] Therefore this studyis focused on developing the proper gel polymer electrolytesbased on PAN and salts such as LiI and Pr

4N+Iminus in addition

to improving the performance of semiconductor material

2 Method and Methodology

21 Preparation of ZnO Working Electrode ZnO (Aldrich99 060 g) acetic acid (Aldrich 98 550 cm3) TritonX-100 (Aldrich 98 5 drops) and ethanol (Aldrich 98400 cm3) were mixed together and ground well and theresultant solution sonicated for 15min Next the solutionwassprayed onto an FTO glass (10Ω cmminus2) using spray pyrolysistechnique at a temperature of 150∘C and subsequently thesample was sintered at 500∘C for 30min and was allowedto cool down to 80∘C Then the sample was immersed inthe dye solution (indoline D-358 3 times 10minus4M in 1 1 volumeratio of acetonitriletert-butyl alcohol) for 12 hoursThe sameprocedure was followed to prepare the SnO

2-based DSCs

through the use of colloidal SnO2(300 cm3) in place of

ZnO

22 Preparation of SnO2ZnO Composite Working ElectrodeColloidal SnO

2(Alfa-Aesar 300 cm3) acetic acid (Aldrich

98 10 drops) Triton X-100 (Aldrich 98 3 drops) ethanol(Aldrich 98 400 cm3) and different amounts of ZnO(Aldrich gt 97 lt50 nm) varying from 000 g to 010 g weremixed thoroughly and the resulting SnO

2ZnO suspensions

were used separately to make devices with varying percent-ages of ZnO after undergoing ultrasonic treatment In eachcase the SnO

2ZnO suspensions were sprayed onto well-

cleaned FTO glass (10Ω cmminus2) plates heated to 150∘C on a(preheated) hotplate Then all the samples were sintered at500∘C for 30 minutes and allowed to cool down to 80∘CThe samples were then immersed in an indoline D-358dye solution for 12 hours and the dye coated-SnO

2ZnO

films were rinsed with acetonitrile to remove any physicallyadsorbed dye molecules Next the electrolyte was sand-wiched between the FTOSnO

2ZnO working electrode and

a lightly platinized FTO counterelectrode (sim7Ωsq Aldrich)to assemble the solar cell device

23 Preparation of Liquid Electrolyte 155 g of dimethylpropyl imidazolium iodide 065 g of 4-tert-butylpyridine(Aldrich 98) 013 g of LiI (Aldrich 99) 012 g of iodine(Aldrich 98) and 759 g of acetonitrile (Aldrich 97) weremixed well in an environment of nitrogen and purged withnitrogen for 14 hours

24 Preparation of Gel Polymer Electrolytes In this experi-ment 0225 g of polyacrylonitrile (Aldrich) 0525 g of ethy-lene carbonate (Aldrich 98) 0750 g of propylene carbonate(Aldrich 99) and 0020 g of iodine (Aldrich 98) weremixed and well stirred in a magnetic stirrer for 12 hours0150 g of LiI (Aldrich 99) (electrolyte Y) and 0150 g ofPr4N+Iminus (Aldrich 98) (electrolyte X) were used separately

to prepare the gel electrolyte Each time the electrolyteswere stirred at 80∘C until the mixture turned into a clearhomogeneous viscous gel In each case the gel electrolyteswere subsequently pressed by sandwiching thembetween twoclean glass plates to obtain a free-standing polymer filmTheywere subsequently dried in a vacuum desiccator overnight atroom temperature to remove any absorbed moisture

3 Results and Discussion

First XRD spectrumwas studied for the SnO2ZnO compos-

ite system in order to verify the presence of both materialsRespective plane values for each material were also identifiedand presented in XRD image as shown in Figure 1

SEM images were obtained in order to study the mor-phology of the semiconductor film Figure 2(a) gives evidencefor enhancement of dye adsorption due to the increaseof surface area thus giving higher photocurrent densityPorous nature of ZnO film will also lead to better electrolytepenetration and also higher recombination As these twofactors are competing effects through the result we obtainedwe can conclude that most dominant factor in this situationis recombination effects According to Figure 2(c) it showssuitable porous structurewhich can avoid negative effects dueto electrolyte penetration into deep sites of the network

International Journal of Photoenergy 3

ZnO(100)

ZnO(002)

ZnO(101)

ZnO(102)

0

60

120

Inte

nsity

(au

) (110)SnO2

(211)SnO2

(002)SnO2

(220)SnO2

30 40 50 60202120579 (deg)

Figure 1 XRD spectrum for SnO2ZnO composite system

(a) (b)

(c)

Figure 2 SEM images of (a) ZnO (b) SnO2 and (c) SnO

2ZnO composite systems

The variation of solar cell parameters was observedwith the variation of ZnO amount and observed resultsare depicted in Figure 3 The reasoning for this sinusoidalvariation of119881OC and 119869SC has been given in the next paragraph

The results of 119869SC and 119881OC and efficiency of optimizedcomposition of ZnO SnO

2 and SnO

2ZnOcomposite system

have been given in Table 1 and Figure 4 When ZnO isused as the coating material it is possible that ZnO being asemiconducting material would act in a different manner toinsulating materials For SnO

2ZnO DSC injected electrons

from the excited dye molecules attached to ZnO outer layerwould fill the conduction band of ZnO and then would betransferred to the conduction band of the SnO

2 According

to conduction band positions of ZnO (minus43 eVwith respectto vacuum level) and SnO

2(minus50 eV with respect to vac-

uum level) and the results which were obtained for theSnO2ZnO composite system the above assumption seems

to be more valid as the electrons try to move towardsthe lower energy according to thermodynamics [23] FirstSnO2ZnO composite system showed lower 119881OC and 119869SC

values due to the recombination occurring at uncoveredsites of the SnO

2network When the amount of ZnO is

increased SnO2nanoparticles tend to become fully covered

with ZnO nanoparticles and thereby the recombinationoccurring at the interfaces of dyed-SnO

2electrolyte will be

reduced The reason is that the electrons in the conductionband of SnO

2have a lesser possibility to reach the surface

traps of the ZnO coating layer in order to recombine withtriiodide ions or oxidized dye molecules After the certainpoint of ZnO amount in Figure 3 119881OC and 119869SC started todecrease This is possibly due to the lower electron tunnelingprobability through ZnO coating layer as the higher ZnOamount will lead to increase the coating layer thickness[21]


05

06

07

01 02 03 0400Molar ratio

ZnO

VO

C(V

)

(a)

6

8

10

ZnO

J SC

(mA

cmminus2)


(b)

00 01 02 03 040

1

2

3

Molar ratio

Effici

ency

(120578) (

)

ZnO(c)

03

04

05

06

07

Fill

fact

or


ZnO(d)

Figure 3 Variations of solar cell parameters of DSCs made using various compositions of ZnO-coated SnO2on with electrolyteX Variation

of (a) 119881OC (b) 119869SC (c) efficiency and (d) fill factor respectively under 100mWcmminus2 illumination

01 02 03 04 05 06 0700Voltage (V)

Curr

ent d

ensit

y (m

Acm

minus2)

0

2

4

6

8

10

ZnO with electrolyte XZnO with electrolyte Y

(a)

SnO2ZnO with electrolyte XSnO2ZnO with electrolyte Y

Curr

ent d

ensit

y (m

Acm

minus2)

0

2

4

6

8

10

12

01 02 03 04 05 0600Voltage (V)

(b)

Figure 4 I-V characteristics curves of the QSDSCs fabricated with composite systems (a) pure ZnO and (b) SnO2ZnO with electrolytes X

and Y


ZnO alone

0

10

20

30

IPCE

800500 600 700400300Wavelength (nm)

Electrolyte XElectrolyte Y

(a)

400 500 600 700 800300Wavelength (nm)

0

10

20

30

40

50

IPCE


For composite SnO2ZnO system

(b)

Figure 5 IPCE curves of the QSDSCs fabricated with composite systems (a) ZnO alone and (b) SnO2ZnO with electrolytes X and Y

Table 1 IV characteristics of SnO2ZnO composite DSCs

Electrolyte System 119869SC (mA cmminus2) 119881OC (V) Fill factor Efficiency

XSnO2

780 046 035 12ZnO 670 068 040 18

SnO2ZnO 102 058 057 34

YSnO2

920 045 048 20ZnO 930 056 055 29

SnO2ZnO 111 057 063 40

Liquid SnO2ZnO 135 0672 0647 59

Table 2 Amount of dye adsorbed and bond distances

System Dye amount (times10minus5mol Lminus1 cmminus2) Distance between two consecutive cations (gt) Isoelectric point (simpH)SnO2

400 Sn4+-Sn4+ 32 55SnO2ZnO 491 Zn2+-Zn2+ 52 87

ZnO 470 100

The devices fabricated with the electrolyte containing Li+ions showed higher 119869SC and lower 119881OC compared to thoseconsisting of Pr

4N+ ions in the electrolyteThepresence of the

Li+ ions increases the amorphous nature of the gel electrolytedue to the formation of cross-linking sites with polymerbackbone thus enhancing the diffusivity of the triiodideions (for Li+ ion based electrolyte 17 times 10minus7 cm2 sminus1 andfor Pr

4N+ ion based electrolyte 990 times 10minus8 cm2 sminus1) Li+

ions can be adsorbed onto the semiconductor surface thuslowering the conduction band level of the semiconductor[22]This effectwill increase the 119869SC while lowering119881OC Sincethe Pr

4N+ions do not contain lone-pair or low-lying empty

orbitals there is no possibility for adsorption of Pr4N+ ions

onto the semiconductor surface and119881OC values obtained alsoseem to agree with this argument This has been reported byseveral workers on the behavior of LiI and Pr

4N+Iminus as salts

[24ndash26]

Table 3 Zeta potential values for SnO2ZnO composite system

System Zeta potential (mV)SnO2

minus184SnO2ZnO +283

ZnO +350

Since IPCE measurements were done in short circuitconditions this does not indicate the efficiency of the devicewhich is given under AM 15 conditions as depicted inFigure 5 It gives an idea about 119869SC of the device IPCE valueof the SnO

2ZnO composite system with the electrolyte Y

has shown a maximum value of about 50 in the wavelengthrange around 650 nm and it showed a much broader curvesupporting its 119869SC value This might be due to the favorablebonding nature between ZnO and dye molecules which leadsto increase in the electron injection efficiency


00

05

10

15

20Ab

sorb

ance

(au

)

500 600 700400Wavelength (nm)

D358 dye solutionSnO2ZnO

(a)

00

01

02

03

04

05

Abso

rban

ce (a

u)


SnO2ZnO

SnO2

ZnO

(b)

Figure 6 (a) UV-visible absorption spectra of indoline D358 dye in 1 1 volume ratio of acetonitriletert-butyl alcohol (solid line) and systemconsists of dyeZnOSnO

2film on the FTO substrate (dotted line) and (b) disrobed dye solution from 1 cm times 1 cm films

Table 4 Electron lifetime charge transport time chemical capacitance and resistance values obtained for each composite system of theDSCs with electrolytes X and Y

Electrolyte System 119877

119904

(Ω)119877ct(Ω)

119877

119905

(Ω)119862

120583

(10minus6 F)120591

119890

(ms)119871

119899

(10minus6m)119863

119890

(10minus9m2 sminus1)

X SnO2ZnO 23 1640 760 300 492 79 127

ZnO alone 80 1750 420 410 718 110 168

Y SnO2ZnO 20 142 782 220 312 230 168

ZnO alone 11 128 362 400 512 320 200

Tabulated results for distance between two consecutivecations and isoelectric point positively direct to the expla-nation of higher performance of SnO

2ZnO-based DSCs as

shown in Table 2 The distance between two consecutiveCOOminus groups of dyemolecules is of about 7 A It will supportthe better anchorage of dye molecules with the SnO

2ZnO

system as the surface of SnO2is covered by the ZnO

System with SnO2alone shows a minus184mV zeta potential

value and it shows better-chelating ability when cations likeZn2+ are introduced to the system according to the resultsshown in Table 3 Increase of zeta potential value towardsmore positive potential will help forming a better interactionbetween the Zn2+ ions in the surface of the composite systemand the COOminus groups of the dye molecules This will lead toa better dye adsorption

According to Figure 6 the absorption spectra for dyedSnO2ZnO composite films show significant broadening of

the bands due to the better anchorage of dye molecules ontothe composite surface Also these absorption spectra exhibita bathochromic shift in the absorption maximum possiblydue to J-aggregation of the sensitizer molecules This mightbe the reason for the somewhat lower performance observedin SnO

2ZnO-based DSCs

The following quantities such as series resistance 119877119904

recombination resistance 119877ct transport resistance 119877119905 andchemical capacitance 119862

120583are taken from Nyquist plots shown

in Figure 7 by fitting an equivalent circuit which is shownin Figure 8 Lifetime of electron 120591

119890 effective diffusion length

of electrons 119871119890 and diffusion coefficient of electrons 119863

119890

are calculated using standard formula [27 28] and they aretabulated in Table 4

Values obtained for 119862120583and 119877ct in electrolyte Y showed

lower values than that of the electrolyte X Due to the lowrecombination resistance high recombination will take placein the system consisting of electrolyteY thus reducing119881OC ofthe devices Adsorption of Li+ ions onto the semiconductorwill lead to lower 119881OC due to the lowering of the energydifference between the redox potential and the Fermi level asconduction band is moved downward

4 Conclusion

ZnO coating layer will help increase the performance ofSnO2-based DSCs by reducing the back tunneling of elec-

trons while efficiently helping the electron transfer towardslower energy levels according to the thermodynamics


0

300

600

900

0 1000 2000

minusZ

998400998400(Ω

)

Z998400 (Ω)

517Hz

193Hz

139 kHz

052Hz

005Hz

010Hz

001Hz

2683 Hz

(a)

0 3000 60000

1000

2000

3000

minusZ

998400998400(Ω

)

Z998400 (Ω)

3907 Hz

0010 Hz

126Hz

023Hz

017Hz

6551 Hz

1206 Hz

(b)

0 100 2000

30

60

minusZ

998400998400(Ω

)

Z998400 (Ω)

7197 Hz

1390 Hz

001Hz019Hz193Hz

5179 Hz

1931 Hz

1000 Hz

(c)

60 1200

20

40

60

minusZ

998400998400(Ω

)

Z998400 (Ω)

4977 Hz

1630 Hz

265 kHz

187Hz

001Hz

1322 Hz

5337 Hz

(d)

Figure 7 Nyquist plots for the devices fabricated with (a) ZnO alone (b) SnO2ZnOwith electrolyteX and (c) ZnO alone and (d) SnO

2ZnO

with electrolyte Y under dark and forward bias at minus058V

Rs

Rct RPt

CPtC120583

Zd

Figure 8 The simplified equivalent circuit of the DSCs fabri-cated by device structure of FTO glass substrateSnO

2ZnOdye

electrolytelightly platinized FTO glass substrate 119877119904is the series

resistance which corresponds to the transport resistance of thetransparent conduction oxide substrate 119877ct and 119862120583 are the chargerecombination resistance at the triple junctions and the chemicalcapacitance respectively 119877Pt and 119862Pt are the charge transfer resis-tance at the Ptelectrolyte interfaces and the interfacial capacitancerespectively and 119885

119889is the Nernst diffusion impedance of the redox

species in the electrolyte medium

process Reduction of recombination and increased dyeabsorption will lead to increase in the overall performanceof SnO

2ZnO composite solar cell device compared to the

SnO2-based DSCs Also liquid electrolyte based SnO

2ZnO

composite solar cell device showed the best performance

compared to the other two types of gel electrolyte basedDSCs Li salt-based DSCs gave higher performance than thatof the Pr

4N+Iminus salt-based DSCs due to its ability of formation

more amorphous gel electrolytes

Competing Interests

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

Acknowledgments

Financial support from the National Research Council SriLanka through Research Grant no NRC 08-17 is gratefullyacknowledged The authors also wish to thank Professor JM S Bandara of the Institute of Fundamental Studies SriLanka for granting permission to use his equipment in IPCEmeasurements

References

[1] B OrsquoRegan and M Gratzel ldquoA low-cost high-efficiency solarcell based on dye-sensitized colloidal TiO

2filmsrdquo Nature vol

353 no 6346 pp 737ndash740 1991


[2] AHagfeldt andMGratzel ldquoMolecular photovoltaicsrdquoAccountsof Chemical Research vol 33 no 5 pp 269ndash277 2000

[3] Z M Jarzebski ldquoPhysical properties of SnO2materials II

Electrical propertiesrdquo Journal ofTheElectrochemical Society vol123 no 9 pp 299Cndash310C 1976

[4] HWang B Li J Gao et al ldquoSnO2hollow nanospheres enclosed

by single crystalline nanoparticles for highly efficient dye-sensitized solar cellsrdquo CrystEngComm vol 14 no 16 pp 5177ndash5181 2012

[5] B Onwona-Agyeman M Nakao and G R A KumaraldquoPhotoelectrochemical solar cells made from SnO2ZnO filmssensitized with an indoline dyerdquo Journal of Materials Researchvol 25 no 9 pp 1838ndash1841 2010

[6] K Tennakone G R R A Kumara I R M Kottegoda and VP S Perera ldquoAn efficient dye-sensitized photoelectrochemicalsolar cell made from oxides of tin and zincrdquo Chemical Commu-nications no 1 pp 15ndash16 1999

[7] G R R A Kumara K Tennakone V P S Perera A KonnoS Kaneko and M Okuya ldquoSuppression of recombinations ina dye-sensitized photoelectrochemicalcell made from a film oftin IV oxide crystallites coated with a thinlayer of aluminiumoxiderdquo Journal of Physics D Applied Physics vol 34 no 6 pp868ndash873 2001

[8] G R A Kumara A Konno and K Tennakone ldquoPhotoelectro-chemical cellsmade fromSnO

2ZnOfilms sensitizedwith eosin

dyesrdquo Chemistry Letters vol 2 pp 180ndash181 2001[9] F Bella E D Ozzello S Bianco and R Bongiovanni ldquoPhoto-

polymerization of acrylicmethacrylic gel-polymer electrolytemembranes for dye-sensitized solar cellsrdquoChemical EngineeringJournal vol 225 pp 873ndash879 2013

[10] C-W Tu K-Y Liu A-T Chien C-H Lee K-C Ho and K-F Lin ldquoPerformance of gelled-type dye-sensitized solar cellsassociated with glass transition temperature of the gelatinizingpolymersrdquo European Polymer Journal vol 44 no 3 pp 608ndash614 2008

[11] M-K Song Y-T Kim Y T Kim B W Cho B N Popov andH-W Rhee ldquoThermally stable gel polymer electrolytesrdquo Journalof the Electrochemical Society vol 150 no 4 pp A439ndashA4442003

[12] T M W J Bandara M A K L Dissanayake W J M J SR Jayasundara I Albinsson and B-E Mellander ldquoEfficiencyenhancement in dye sensitized solar cells using gel polymerelectrolytes based on a tetrahexylammonium iodide and MgI2binary iodide systemrdquo Physical Chemistry Chemical Physics vol14 no 24 pp 8620ndash8627 2012

[13] E Stathatos P Lianos S M Zakeeruddin P Liska and MGratzel ldquoA quasi-solid-state dye-sensitized solar cell based ona sol-gel nanocomposite electrolyte containing ionic liquidrdquoChemistry of Materials vol 15 no 9 pp 1825ndash1829 2003

[14] C H Ahn J-D Jeon and S-Y Kwak ldquoPhotoelectrochemicaleffects of hyperbranched polyglycerol in gel electrolytes on theperformance of dye-sensitized solar cellsrdquo Journal of Industrialand Engineering Chemistry vol 18 no 6 pp 2184ndash2190 2012

[15] M A K L Dissanayake C A Thotawatthage G K RSenadeera T M W J Bandara W J M J S R Jayasunderaand B-E Mellander ldquoEfficiency enhancement by mixed cationeffect in dye-sensitized solar cells with PAN based gel polymerelectrolyterdquo Journal of Photochemistry and Photobiology AChemistry vol 246 pp 29ndash35 2012

[16] N H Zainol S M Samin L Othman K B Isa W G Chongand Z Osman ldquoMagnesium ion-based gel polymer electrolytes

ionic conduction and infrared spectroscopy studiesrdquo Interna-tional Journal of Electrochemical Science vol 8 no 3 pp 3602ndash3614 2013

[17] ZChen F LiH Yang T Yi andCHuang ldquoA thermostable andlong-term-stable ionic-liquid-based gel electrolyte for efficientdye-sensitized solar cellsrdquo ChemPhysChem vol 8 no 9 pp1293ndash1297 2007

[18] Z Chen H Yang X Li F Li T Yi and C Huang ldquoTher-mostable succinonitrile-based gel electrolyte for efficient long-life dye-sensitized solar cellsrdquo Journal of Materials Chemistryvol 17 no 16 pp 1602ndash1607 2007

[19] P Wang S M Zakeeruddin I Exnar and M Gratzel ldquoHighefficiency dye-sensitized nanocrystalline solar cells based onionic liquid polymer gel electrolyterdquoChemical Communicationsno 24 pp 2972ndash2973 2002

[20] W Xiang W Huang U Bach and L Spiccia ldquoStable highefficiency dye-sensitized solar cells based on a cobalt polymergel electrolyterdquo Chemical Communications vol 49 no 79 pp8997ndash8999 2013

[21] W M N M B Wanninayake K Premaratne G R A Kumaraand R M G Rajapakse ldquoA study of the efficiency enhancementof the gel electrolyte-based SnO

2dye-sensitized solar cells

through the use of thin insulating layersrdquo Electrochimica Actavol 210 pp 138ndash146 2016

[22] W M N M B Wanninayake K Premaratne G R A Kumaraand R M G Rajapakse ldquoUse of lithium iodide and tetrapropy-lammonium iodide in gel electrolytes for improved perfor-mance of quasi-solid-state dye-sensitized solar cells recordingan efficiency of 640rdquo Electrochimica Acta vol 191 pp 1037ndash1043 2016

[23] G R R A Kumara K Murakami M Shimomura et al ldquoElec-trochemical impedance and X-ray photoelectron spectroscopicanalysis of dye-sensitized liquid electrolyte based SnO

2ZnO

solar cellrdquo Journal of Photochemistry and Photobiology AChemistry vol 215 no 1 pp 1ndash10 2010

[24] G Liang Z Zhong S Qu et al ldquoNovel in situ crosslinkedpolymer electrolyte for solid-state dye-sensitized solar cellsrdquoJournal of Materials Science vol 48 no 18 pp 6377ndash6385 2013

[25] S Agarwala L N S AThummalakunta C A Cook et al ldquoCo-existence of LiI and KI in filler-free quasi-solid-state electrolytefor efficient and stable dye-sensitized solar cellrdquo Journal of PowerSources vol 196 no 3 pp 1651ndash1656 2011

[26] S-H Anna Lee A-M S Jackson A Hess et al ldquoInfluence ofdifferent iodide salts on the performance of dye-sensitized solarcells containing phosphazene-based nonvolatile electrolytesrdquoThe Journal of Physical Chemistry C vol 114 no 35 pp 15234ndash15242 2010

[27] F Fabregat-Santiago J Bisquert E Palomares et al ldquoCorrela-tion between photovoltaic performance and impedance spec-troscopy of dye-sensitized solar cells based on ionic liquidsrdquoThe Journal of Physical Chemistry C vol 111 no 17 pp 6550ndash6560 2007

[28] J W Ondersma and T W Hamann ldquoImpedance investigationof dye-sensitized solar cells employing outer-sphere redoxshuttlesrdquoThe Journal of Physical Chemistry C vol 114 no 1 pp638ndash645 2010

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Analytical ChemistryInternational Journal of


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Organic Chemistry International

ElectrochemistryInternational Journal of



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performance and suitability of composite SnO2ZnOwith gel

polymer electrolytes are reported [5ndash8]Even though the use of gel polymer electrolytes sacrifices

the performance of DSCs to some extent due to low ionmobility it shows cohesive nature of solids and diffusivenature of liquids while showing good stability in outdoorapplications due to their promising properties such as ther-mal stability nontoxicity lower flammability and environ-mental friendliness Generally the diffusivity of triiodide ionsin gel based electrolytes lies in 10minus6 to 10minus7 cm2 sminus1 rangeElectrolytes based on organic solvents or ionic liquids canbe gelated or polymerized by dispersing suitable polymermaterials to obtain quasi-solid-state electrolytes Polymerbackbone in gel electrolyte medium will help the transportof ions and this ion conduction is called the Grotthussmechanism

There is a vast amount of literature available for theDSCs fabricated with polymer based gel electrolytes and theireffects on the performance of the device [9ndash20] In summarypolymethylhydrosiloxane poly(vinylidenefluoride-co-hexafluor-opropylene) (PVDFHFP) 3-methoxypropionitrile (MPN)24-di-O-dimethylbenzylidene-D-sorbitol (DMDBS) poly[di(ethylene glycol)-2-ethyl hexyl ether acrylate] (PDEA) poly(vinylpyridine-co-acrylonitrile) [P(VP-coAN)] poly(ethyl-ene oxide) (PEO) polyvinylpyridine hydroxystearic acidimidazole polymers polysaccharides poly(epichlorohydrin-co-ethylene oxide) and polyacrylonitrile (PAN) polymerswere used in the past few decades Also the other trendof gelatin mechanism is by the introduction of nanofillerssuch as TiO

2 Al2O3 fumed silica and many other inorganic

materials into the host liquid electrolytes Somehow thesetypes of polymer based gel electrolytes gave an efficiencyof about 7 The conductivities of the gel polymer basedelectrolytes mainly depended on the oligomer size or molec-ular weight and salts used in the gel polymer electrolyteLiI salt and PAN-based gel polymer [21] electrolytes aremost frequently used in fabrication of DSCs in addition tomixed salts based gel electrolytes [22] Therefore this studyis focused on developing the proper gel polymer electrolytesbased on PAN and salts such as LiI and Pr

4N+Iminus in addition

to improving the performance of semiconductor material

2 Method and Methodology

21 Preparation of ZnO Working Electrode ZnO (Aldrich99 060 g) acetic acid (Aldrich 98 550 cm3) TritonX-100 (Aldrich 98 5 drops) and ethanol (Aldrich 98400 cm3) were mixed together and ground well and theresultant solution sonicated for 15min Next the solutionwassprayed onto an FTO glass (10Ω cmminus2) using spray pyrolysistechnique at a temperature of 150∘C and subsequently thesample was sintered at 500∘C for 30min and was allowedto cool down to 80∘C Then the sample was immersed inthe dye solution (indoline D-358 3 times 10minus4M in 1 1 volumeratio of acetonitriletert-butyl alcohol) for 12 hoursThe sameprocedure was followed to prepare the SnO

2-based DSCs

through the use of colloidal SnO2(300 cm3) in place of

ZnO

22 Preparation of SnO2ZnO Composite Working ElectrodeColloidal SnO

2(Alfa-Aesar 300 cm3) acetic acid (Aldrich

98 10 drops) Triton X-100 (Aldrich 98 3 drops) ethanol(Aldrich 98 400 cm3) and different amounts of ZnO(Aldrich gt 97 lt50 nm) varying from 000 g to 010 g weremixed thoroughly and the resulting SnO

2ZnO suspensions

were used separately to make devices with varying percent-ages of ZnO after undergoing ultrasonic treatment In eachcase the SnO

2ZnO suspensions were sprayed onto well-

cleaned FTO glass (10Ω cmminus2) plates heated to 150∘C on a(preheated) hotplate Then all the samples were sintered at500∘C for 30 minutes and allowed to cool down to 80∘CThe samples were then immersed in an indoline D-358dye solution for 12 hours and the dye coated-SnO

2ZnO

films were rinsed with acetonitrile to remove any physicallyadsorbed dye molecules Next the electrolyte was sand-wiched between the FTOSnO

2ZnO working electrode and

a lightly platinized FTO counterelectrode (sim7Ωsq Aldrich)to assemble the solar cell device

23 Preparation of Liquid Electrolyte 155 g of dimethylpropyl imidazolium iodide 065 g of 4-tert-butylpyridine(Aldrich 98) 013 g of LiI (Aldrich 99) 012 g of iodine(Aldrich 98) and 759 g of acetonitrile (Aldrich 97) weremixed well in an environment of nitrogen and purged withnitrogen for 14 hours

24 Preparation of Gel Polymer Electrolytes In this experi-ment 0225 g of polyacrylonitrile (Aldrich) 0525 g of ethy-lene carbonate (Aldrich 98) 0750 g of propylene carbonate(Aldrich 99) and 0020 g of iodine (Aldrich 98) weremixed and well stirred in a magnetic stirrer for 12 hours0150 g of LiI (Aldrich 99) (electrolyte Y) and 0150 g ofPr4N+Iminus (Aldrich 98) (electrolyte X) were used separately

to prepare the gel electrolyte Each time the electrolyteswere stirred at 80∘C until the mixture turned into a clearhomogeneous viscous gel In each case the gel electrolyteswere subsequently pressed by sandwiching thembetween twoclean glass plates to obtain a free-standing polymer filmTheywere subsequently dried in a vacuum desiccator overnight atroom temperature to remove any absorbed moisture

3 Results and Discussion

First XRD spectrumwas studied for the SnO2ZnO compos-

ite system in order to verify the presence of both materialsRespective plane values for each material were also identifiedand presented in XRD image as shown in Figure 1

SEM images were obtained in order to study the mor-phology of the semiconductor film Figure 2(a) gives evidencefor enhancement of dye adsorption due to the increaseof surface area thus giving higher photocurrent densityPorous nature of ZnO film will also lead to better electrolytepenetration and also higher recombination As these twofactors are competing effects through the result we obtainedwe can conclude that most dominant factor in this situationis recombination effects According to Figure 2(c) it showssuitable porous structurewhich can avoid negative effects dueto electrolyte penetration into deep sites of the network


ZnO(100)

ZnO(002)

ZnO(101)

ZnO(102)

0

60

120

Inte

nsity

(au

) (110)SnO2

(211)SnO2

(002)SnO2

(220)SnO2

30 40 50 60202120579 (deg)


(a) (b)

(c)





2 and SnO





2 According














05

06

07


ZnO

VO

C(V

)

(a)

6

8

10

ZnO

J SC

(mA

cmminus2)


(b)

00 01 02 03 040

1

2

3

Molar ratio

Effici

ency

(120578) (

)

ZnO(c)

03

04

05

06

07

Fill

fact

or


ZnO(d)



01 02 03 04 05 06 0700Voltage (V)

Curr

ent d

ensit

y (m

Acm

minus2)

0

2

4

6

8

10


(a)


Curr

ent d

ensit

y (m

Acm

minus2)

0

2

4

6

8

10

12

01 02 03 04 05 0600Voltage (V)

(b)


and Y


ZnO alone

0

10

20

30

IPCE

800500 600 700400300Wavelength (nm)


(a)

400 500 600 700 800300Wavelength (nm)

0

10

20

30

40

50

IPCE



(b)




XSnO2

780 046 035 12ZnO 670 068 040 18

SnO2ZnO 102 058 057 34

YSnO2

920 045 048 20ZnO 930 056 055 29

SnO2ZnO 111 057 063 40

Liquid SnO2ZnO 135 0672 0647 59



400 Sn4+-Sn4+ 32 55SnO2ZnO 491 Zn2+-Zn2+ 52 87

ZnO 470 100









4N+Iminus as salts

[24ndash26]




ZnO +350





00

05

10

15

20Ab

sorb

ance

(au

)



(a)

00

01

02

03

04

05

Abso

rban

ce (a

u)


SnO2ZnO

SnO2

ZnO

(b)





119904

(Ω)119877ct(Ω)

119877

119905

(Ω)119862

120583

(10minus6 F)120591

119890

(ms)119871

119899

(10minus6m)119863

119890


X SnO2ZnO 23 1640 760 300 492 79 127

ZnO alone 80 1750 420 410 718 110 168

Y SnO2ZnO 20 142 782 220 312 230 168

ZnO alone 11 128 362 400 512 320 200


2ZnO-based DSCs as


2ZnO






2ZnO-based DSCs







119890




4 Conclusion




0

300

600

900

0 1000 2000

minusZ

998400998400(Ω

)

Z998400 (Ω)

517Hz

193Hz

139 kHz

052Hz

005Hz

010Hz

001Hz

2683 Hz

(a)

0 3000 60000

1000

2000

3000

minusZ

998400998400(Ω

)

Z998400 (Ω)

3907 Hz

0010 Hz

126Hz

023Hz

017Hz

6551 Hz

1206 Hz

(b)

0 100 2000

30

60

minusZ

998400998400(Ω

)

Z998400 (Ω)

7197 Hz

1390 Hz

001Hz019Hz193Hz

5179 Hz

1931 Hz

1000 Hz

(c)

60 1200

20

40

60

minusZ

998400998400(Ω

)

Z998400 (Ω)

4977 Hz

1630 Hz

265 kHz

187Hz

001Hz

1322 Hz

5337 Hz

(d)


2ZnO


Rs

Rct RPt

CPtC120583

Zd


2ZnOdye








2ZnO





Competing Interests


Acknowledgments


References



353 no 6346 pp 737ndash740 1991































2ZnO
















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


ZnO(100)

ZnO(002)

ZnO(101)

ZnO(102)

0

60

120

Inte

nsity

(au

) (110)SnO2

(211)SnO2

(002)SnO2

(220)SnO2

30 40 50 60202120579 (deg)


(a) (b)

(c)





2 and SnO





2 According














05

06

07


ZnO

VO

C(V

)

(a)

6

8

10

ZnO

J SC

(mA

cmminus2)


(b)

00 01 02 03 040

1

2

3

Molar ratio

Effici

ency

(120578) (

)

ZnO(c)

03

04

05

06

07

Fill

fact

or


ZnO(d)



01 02 03 04 05 06 0700Voltage (V)

Curr

ent d

ensit

y (m

Acm

minus2)

0

2

4

6

8

10


(a)


Curr

ent d

ensit

y (m

Acm

minus2)

0

2

4

6

8

10

12

01 02 03 04 05 0600Voltage (V)

(b)


and Y


ZnO alone

0

10

20

30

IPCE

800500 600 700400300Wavelength (nm)


(a)

400 500 600 700 800300Wavelength (nm)

0

10

20

30

40

50

IPCE



(b)




XSnO2

780 046 035 12ZnO 670 068 040 18

SnO2ZnO 102 058 057 34

YSnO2

920 045 048 20ZnO 930 056 055 29

SnO2ZnO 111 057 063 40

Liquid SnO2ZnO 135 0672 0647 59



400 Sn4+-Sn4+ 32 55SnO2ZnO 491 Zn2+-Zn2+ 52 87

ZnO 470 100









4N+Iminus as salts

[24ndash26]




ZnO +350





00

05

10

15

20Ab

sorb

ance

(au

)



(a)

00

01

02

03

04

05

Abso

rban

ce (a

u)


SnO2ZnO

SnO2

ZnO

(b)





119904

(Ω)119877ct(Ω)

119877

119905

(Ω)119862

120583

(10minus6 F)120591

119890

(ms)119871

119899

(10minus6m)119863

119890


X SnO2ZnO 23 1640 760 300 492 79 127

ZnO alone 80 1750 420 410 718 110 168

Y SnO2ZnO 20 142 782 220 312 230 168

ZnO alone 11 128 362 400 512 320 200


2ZnO-based DSCs as


2ZnO






2ZnO-based DSCs







119890




4 Conclusion




0

300

600

900

0 1000 2000

minusZ

998400998400(Ω

)

Z998400 (Ω)

517Hz

193Hz

139 kHz

052Hz

005Hz

010Hz

001Hz

2683 Hz

(a)

0 3000 60000

1000

2000

3000

minusZ

998400998400(Ω

)

Z998400 (Ω)

3907 Hz

0010 Hz

126Hz

023Hz

017Hz

6551 Hz

1206 Hz

(b)

0 100 2000

30

60

minusZ

998400998400(Ω

)

Z998400 (Ω)

7197 Hz

1390 Hz

001Hz019Hz193Hz

5179 Hz

1931 Hz

1000 Hz

(c)

60 1200

20

40

60

minusZ

998400998400(Ω

)

Z998400 (Ω)

4977 Hz

1630 Hz

265 kHz

187Hz

001Hz

1322 Hz

5337 Hz

(d)


2ZnO


Rs

Rct RPt

CPtC120583

Zd


2ZnOdye








2ZnO





Competing Interests


Acknowledgments


References



353 no 6346 pp 737ndash740 1991































2ZnO
















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


05

06

07


ZnO

VO

C(V

)

(a)

6

8

10

ZnO

J SC

(mA

cmminus2)


(b)

00 01 02 03 040

1

2

3

Molar ratio

Effici

ency

(120578) (

)

ZnO(c)

03

04

05

06

07

Fill

fact

or


ZnO(d)



01 02 03 04 05 06 0700Voltage (V)

Curr

ent d

ensit

y (m

Acm

minus2)

0

2

4

6

8

10


(a)


Curr

ent d

ensit

y (m

Acm

minus2)

0

2

4

6

8

10

12

01 02 03 04 05 0600Voltage (V)

(b)


and Y


ZnO alone

0

10

20

30

IPCE

800500 600 700400300Wavelength (nm)


(a)

400 500 600 700 800300Wavelength (nm)

0

10

20

30

40

50

IPCE



(b)




XSnO2

780 046 035 12ZnO 670 068 040 18

SnO2ZnO 102 058 057 34

YSnO2

920 045 048 20ZnO 930 056 055 29

SnO2ZnO 111 057 063 40

Liquid SnO2ZnO 135 0672 0647 59



400 Sn4+-Sn4+ 32 55SnO2ZnO 491 Zn2+-Zn2+ 52 87

ZnO 470 100









4N+Iminus as salts

[24ndash26]




ZnO +350





00

05

10

15

20Ab

sorb

ance

(au

)



(a)

00

01

02

03

04

05

Abso

rban

ce (a

u)


SnO2ZnO

SnO2

ZnO

(b)





119904

(Ω)119877ct(Ω)

119877

119905

(Ω)119862

120583

(10minus6 F)120591

119890

(ms)119871

119899

(10minus6m)119863

119890


X SnO2ZnO 23 1640 760 300 492 79 127

ZnO alone 80 1750 420 410 718 110 168

Y SnO2ZnO 20 142 782 220 312 230 168

ZnO alone 11 128 362 400 512 320 200


2ZnO-based DSCs as


2ZnO






2ZnO-based DSCs







119890




4 Conclusion




0

300

600

900

0 1000 2000

minusZ

998400998400(Ω

)

Z998400 (Ω)

517Hz

193Hz

139 kHz

052Hz

005Hz

010Hz

001Hz

2683 Hz

(a)

0 3000 60000

1000

2000

3000

minusZ

998400998400(Ω

)

Z998400 (Ω)

3907 Hz

0010 Hz

126Hz

023Hz

017Hz

6551 Hz

1206 Hz

(b)

0 100 2000

30

60

minusZ

998400998400(Ω

)

Z998400 (Ω)

7197 Hz

1390 Hz

001Hz019Hz193Hz

5179 Hz

1931 Hz

1000 Hz

(c)

60 1200

20

40

60

minusZ

998400998400(Ω

)

Z998400 (Ω)

4977 Hz

1630 Hz

265 kHz

187Hz

001Hz

1322 Hz

5337 Hz

(d)


2ZnO


Rs

Rct RPt

CPtC120583

Zd


2ZnOdye








2ZnO





Competing Interests


Acknowledgments


References



353 no 6346 pp 737ndash740 1991































2ZnO
















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


ZnO alone

0

10

20

30

IPCE

800500 600 700400300Wavelength (nm)


(a)

400 500 600 700 800300Wavelength (nm)

0

10

20

30

40

50

IPCE



(b)




XSnO2

780 046 035 12ZnO 670 068 040 18

SnO2ZnO 102 058 057 34

YSnO2

920 045 048 20ZnO 930 056 055 29

SnO2ZnO 111 057 063 40

Liquid SnO2ZnO 135 0672 0647 59



400 Sn4+-Sn4+ 32 55SnO2ZnO 491 Zn2+-Zn2+ 52 87

ZnO 470 100









4N+Iminus as salts

[24ndash26]




ZnO +350





00

05

10

15

20Ab

sorb

ance

(au

)



(a)

00

01

02

03

04

05

Abso

rban

ce (a

u)


SnO2ZnO

SnO2

ZnO

(b)





119904

(Ω)119877ct(Ω)

119877

119905

(Ω)119862

120583

(10minus6 F)120591

119890

(ms)119871

119899

(10minus6m)119863

119890


X SnO2ZnO 23 1640 760 300 492 79 127

ZnO alone 80 1750 420 410 718 110 168

Y SnO2ZnO 20 142 782 220 312 230 168

ZnO alone 11 128 362 400 512 320 200


2ZnO-based DSCs as


2ZnO






2ZnO-based DSCs







119890




4 Conclusion




0

300

600

900

0 1000 2000

minusZ

998400998400(Ω

)

Z998400 (Ω)

517Hz

193Hz

139 kHz

052Hz

005Hz

010Hz

001Hz

2683 Hz

(a)

0 3000 60000

1000

2000

3000

minusZ

998400998400(Ω

)

Z998400 (Ω)

3907 Hz

0010 Hz

126Hz

023Hz

017Hz

6551 Hz

1206 Hz

(b)

0 100 2000

30

60

minusZ

998400998400(Ω

)

Z998400 (Ω)

7197 Hz

1390 Hz

001Hz019Hz193Hz

5179 Hz

1931 Hz

1000 Hz

(c)

60 1200

20

40

60

minusZ

998400998400(Ω

)

Z998400 (Ω)

4977 Hz

1630 Hz

265 kHz

187Hz

001Hz

1322 Hz

5337 Hz

(d)


2ZnO


Rs

Rct RPt

CPtC120583

Zd


2ZnOdye








2ZnO





Competing Interests


Acknowledgments


References



353 no 6346 pp 737ndash740 1991































2ZnO
















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


00

05

10

15

20Ab

sorb

ance

(au

)



(a)

00

01

02

03

04

05

Abso

rban

ce (a

u)


SnO2ZnO

SnO2

ZnO

(b)





119904

(Ω)119877ct(Ω)

119877

119905

(Ω)119862

120583

(10minus6 F)120591

119890

(ms)119871

119899

(10minus6m)119863

119890


X SnO2ZnO 23 1640 760 300 492 79 127

ZnO alone 80 1750 420 410 718 110 168

Y SnO2ZnO 20 142 782 220 312 230 168

ZnO alone 11 128 362 400 512 320 200


2ZnO-based DSCs as


2ZnO






2ZnO-based DSCs







119890




4 Conclusion




0

300

600

900

0 1000 2000

minusZ

998400998400(Ω

)

Z998400 (Ω)

517Hz

193Hz

139 kHz

052Hz

005Hz

010Hz

001Hz

2683 Hz

(a)

0 3000 60000

1000

2000

3000

minusZ

998400998400(Ω

)

Z998400 (Ω)

3907 Hz

0010 Hz

126Hz

023Hz

017Hz

6551 Hz

1206 Hz

(b)

0 100 2000

30

60

minusZ

998400998400(Ω

)

Z998400 (Ω)

7197 Hz

1390 Hz

001Hz019Hz193Hz

5179 Hz

1931 Hz

1000 Hz

(c)

60 1200

20

40

60

minusZ

998400998400(Ω

)

Z998400 (Ω)

4977 Hz

1630 Hz

265 kHz

187Hz

001Hz

1322 Hz

5337 Hz

(d)


2ZnO


Rs

Rct RPt

CPtC120583

Zd


2ZnOdye








2ZnO





Competing Interests


Acknowledgments


References



353 no 6346 pp 737ndash740 1991































2ZnO
















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


0

300

600

900

0 1000 2000

minusZ

998400998400(Ω

)

Z998400 (Ω)

517Hz

193Hz

139 kHz

052Hz

005Hz

010Hz

001Hz

2683 Hz

(a)

0 3000 60000

1000

2000

3000

minusZ

998400998400(Ω

)

Z998400 (Ω)

3907 Hz

0010 Hz

126Hz

023Hz

017Hz

6551 Hz

1206 Hz

(b)

0 100 2000

30

60

minusZ

998400998400(Ω

)

Z998400 (Ω)

7197 Hz

1390 Hz

001Hz019Hz193Hz

5179 Hz

1931 Hz

1000 Hz

(c)

60 1200

20

40

60

minusZ

998400998400(Ω

)

Z998400 (Ω)

4977 Hz

1630 Hz

265 kHz

187Hz

001Hz

1322 Hz

5337 Hz

(d)


2ZnO


Rs

Rct RPt

CPtC120583

Zd


2ZnOdye








2ZnO





Competing Interests


Acknowledgments


References



353 no 6346 pp 737ndash740 1991































2ZnO
















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of































2ZnO
















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of










Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of

research article enhancing performance of sno -based...

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