Influence of the Porosity of the TiO Film on the ...downloads.hindawi.com/journals/ijp/2017/4935265.pdf · ResearchArticle Influence of the Porosity of the TiO 2 Film on the Performance

Research ArticleInfluence of the Porosity of the TiO2 Film on the Performance ofthe Perovskite Solar Cell

Xiaodan Sun1 Jia Xu2 Li Xiao1 Jing Chen12 Bing Zhang13

Jianxi Yao12 and Songyuan Dai13

1State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power UniversityBeijing 102206 China2Beijing Key Laboratory of Energy Safety and Clean Utilization North China Electric Power University Beijing 102206 China3Beijing Key Laboratory of Novel Film Solar Cell North China Electric Power University Beijing 102206 China

Correspondence should be addressed to Jianxi Yao jianxiyaoncepueducn and Songyuan Dai sydaiippaccn

Received 8 October 2016 Accepted 19 December 2016 Published 1 February 2017

Academic Editor Pushpa Pudasaini

Copyright copy 2017 Xiaodan Sun 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

The structure of mesoporous TiO2 (mp-TiO2) films is crucial to the performance of mesoporous perovskite solar cells (PSCs) Inthis study we fabricated highly porous mp-TiO2 films by doping polystyrene (PS) spheres in TiO2 paste The composition of theperovskite films was effectively improved by modifying the mass fraction of the PS spheres in the TiO2 paste Due to the highporosity of the mp-TiO2 film PbI2 and CH3NH3I could sufficiently infiltrate into the network of the mp-TiO2 film which ensuredamore complete transformation to CH3NH3PbI3The surface morphology of the mp-TiO2 film and the photoelectric performanceof the perovskite solar cells were investigated The results showed that an increase in the porosity of the mp-TiO2 film resulted inan improvement in the performance of the PSCs The best device with the optimized mass fraction of 10 wt PS in TiO2 pasteexhibited an efficiency of 1269 which is 25 higher than the efficiency of the PSCs without PS spheres

1 Introduction

Perovskite solar cells based on CH3NH3PbI3 have attractedmuch attention Tremendous progress has been made sincethe seminal work of Kojima et al in 2009 [1] In just six yearspower conversion efficiencies (PCEs) of PSCs have increasedsharply from 38 [1] to 221 [2] which exceeds the PCEsof polycrystalline silicon solar cells [3ndash5] Moreover theirsolution processability and low cost endow them with highpotential for next generation solar cells [4 6]

Two typical PSC structures are widely used includingthe planar heterojunction architectures [7] and the meso-porous structures [8ndash10] Planar perovskite solar cells areadvantageous because they have simple and scalable cellconfigurations [11] In mesoporous structured PSCs semi-conductors including TiO2 ZnO insulating Al2O3 andZrO2 are employed as the electron transporting layer (ETL)or the scaffold of the perovskite layer [12] Due to its

excellent physicochemical properties such as large band gapchemical stability photostability nontoxicity and low cost[13] mesoporous TiO2 is the most widely used electrontransporting material in PSCs The mp-TiO2 film acts asnot only the scaffold of the perovskite layer but also as thepathway for electron transport [14]

It has been reported that the structural properties of themp-TiO2 layer such as particle size [15] thickness [16ndash18] andporosity have a significant influence on the performance ofPSCs [19] Highly porous mp-TiO2 films promote the easyinfiltration of perovskite which subsequently fills the poresA higher deposition of perovskites in mp-TiO2 film resultsin increased light absorption and a higher current density[12 14] Moreover the interface between the mp-TiO2 filmand perovskite film plays a key role in determining the overallconversion efficiency of PSCs [20] Increasing the specificsurface area and porosity of mp-TiO2 film can promote adeeper infiltration of perovskites in TiO2 filmsThis superior

HindawiInternational Journal of PhotoenergyVolume 2017 Article ID 4935265 10 pageshttpsdoiorg10115520174935265

2 International Journal of Photoenergy

FTO glass FTO glass FTO glass

Compact TiO2Compact TiO2 Compact TiO2

TiO2

PbI2PbI2

CH3NH3PbI3

(a)

FTO glass FTO glass FTO glassFTO glass

PS

ThermaltreatmentCompact TiO2 Compact TiO2

Compact TiO2 Compact TiO2

TiO2TiO2

PbI2CH3NH3PbI3

(b)

Figure 1 Schematic illustration of the distribution of PbI2 and TiO2 in mp-TiO2 film (a) without and (b) with PS spheres

infiltration is thought as an effective way to decrease thecontact barrier between the TiO2CH3NH3PbI3 interfaceswhich could improve the transport of carriers in thePSCs Dharani et al [21] used electrospinning to prepareTiO2 nanofibers as the ETL for PSCs The TiO2 nanofiberformed a highly porous structure The excellent porousnetwork resulted in improved loading of PbI2 Therefore theCH3NH3I can infiltrate through the pores to completely reactwith PbI2 Sarkar et al [22] prepared well-organized meso-porous TiO2 photoelectrodes with enlarged pores by blockcopolymer-induced solminusgel assembly TiO2 photoelectrodeswith larger pores are favorable for filling of perovskite in themp-TiO2 filmWithin a certain range devices based on largerpores showed a higher 119869sc and superior performance Rap-somanikis et al [19] synthesized highly meso-macroporousTiO2 thin films as ETLs of PSCs using a solndashgel process andPluronic P-123 block copolymer as the organic templateTheirresults showed that the high porosity enabled the TiO2 thinfilm to act as an ideal host for perovskiteThe efficient contactbetween mp-TiO2 and perovskite enhanced the electrontransport

Methods of controlling the mesoporous networks of mp-TiO2 include changing the size of TiO2 nanoparticles usingamphiphilic block copolymers [14 22] and using templatesMany researchers reported that polystyrene (PS) spheres canbe used as a mesostructured template to fabricate macroand mesoporous TiO2 films in dye-sensitized solar cells(DSSC) because of its size tunability [23 24] By using variouspreparation method and PS spheres with different sizes themorphology of the films can be easily controlled Dionigiet al [25] used PS spheres as structure-directing agents andcoated the PS spheres with titanium dihydroxide to fabricateporous TiO2 films with ordered pore architectures Du etal [24] fabricated hierarchically ordered macro-mesoporousTiO2 films as the interfacial layer of DSSC using PS spheres

as a template Because of the periodically ordered structureand large specific surface of the macro-mesoporous TiO2films a higher 119869sc and a PCE enhanced by 83 wereobtained

However to our knowledge there have been no reportson the use of PS spheres to change the mesoporous net-works of mp-TiO2 film in PSCs In this study we presenta facile method of controlling the porosity of mp-TiO2 byintroducing PS spheres into TiO2 paste which can be aneffective strategy for the development of mesoporous PSCsFigure 1 shows the schematic representation of the reactionprocess studied in this work As shown in Figure 1(a) TiO2nanoparticles are close to each otherThere are only few poresbetween the particles PbI2 cannot fully infiltrate into thenarrow pores of mp-TiO2 without the introduction of PSspheres during the preparation process instead CH3NH3Iwould react with the superficial PbI2 which results in a largeamount of residual PbI2 in the TiO2 film In Figure 1(b)PS spheres can be observed in the TiO2 film before heattreatment Then PS spheres were removed by heat treatmentand a large amount of pores were formed in mesoporousTiO2 film Therefore more PbI2 infiltrated into the filmThe subsequently deposited CH3NH3I reacted more com-pletely with PbI2 which reduced the amount of the residualPbI2 By adjusting the mass fraction of PS spheres in TiO2paste a controllable porous mp-TiO2 film was obtainedThe incorporation of the macropores in mp-TiO2 filmsincreased the perovskite loading in the film and improvedthe contact between the TiO2 and perovskite interface whicheffectively suppressed charge recombination in the interfaceX-ray diffraction and fluorescence lifetime measurementsconfirmed that the increased porosity ensured an adequatereaction between PbI2 and CH3NH3I thus decreasing theamount of residual PbI2 and enhancing the electron injectionfrom the perovskite to mp-TiO2 film The PSCs with the

International Journal of Photoenergy 3

porous TiO2 films showed an enhanced short-circuit currentdensity and higher efficiency

2 Materials and Methods

21 Materials Titanium dioxide paste (18-RT) was pur-chased from Yingkou OPV Tech New Energy Co Ltd Eth-anol (998) and hydrochloric acid (36) were purchasedfrom Beijing Chemical Plant (Beijing China) The 100 nmPS spheres (Mw sim 100000) were purchased from JanusNew-Materials Co Ltd PbI2 (99) was purchased fromAcros CH3NH3I (995) and 221015840771015840-tetrakis-(NN-dip-methoxyphenylamine)-991015840-spirobifluorene (Spiro-OMeTAD)(997) were purchased from Borun Chemicals (NingboChina) Tris(2-(1H-pyrazol-1-yl)-4-tert-butylpyridine)-co-balt(III)tris(bis(trifluoromethylsulfonyl)imide) (FK209-co-balt(III)-TFSI) was purchased from MaterWin Chemicals(Shanghai China) NN-dimethylformamide (DMF) waspurchased from Alfa Aesar Isopropanol was purchased fromJampK Scientific Co Ltd All chemicals were used as receivedGlass substrates with a transparent fluorine-doped tin oxide(FTO sheet resistance 15Ωsquare) layer were used for thePSCs

The solution of the compact TiO2 is prepared by mixingtitanium isopropoxide HCl and ethanol with a volumeratio of 7 22 100 In the solution of compact TiO2 theconcentrations of HCl and ethanol are 7024 and 848respectively For the preparation of the TiO2 paste we firstdiluted the TiO2 paste in ethanol with a ratio of 1 35 Thenthemixturewas added to 100 nmPS sphereswith variouswt(0wt 10 wt and 15 wt) and stirred for 12 h The spiro-MeOTAD solution was prepared by dissolving 723mg spiro-MeOTAD in 1mL chlorobenzene and then 288 120583L TBP andan 8 120583L solution of LiTFSI (520mgmLLiTFSI in acetonitrile)were added

22 Device Fabrication Devices were fabricated on FTOglass substrates with a dimension of 15 cm times 13 cm FirstFTO was partially etched with Zn powder and HCl Thenthe etched FTOwas cleaned using potassium sulfate solutionsoap deionizedwater and ethanol and finally it was sinteredat 500∘C for 30 minutes A compact TiO2 layer was preparedby spin coating compact TiO2 solution followed by annealingat 500∘C for 30minThemesoporous TiO2 filmwas preparedby spin coating 35 120583L TiO2 paste at 5000 rpm for 30 sThen the films were heated to 450∘C for 2 hours with aheating rate of 5∘Cmin 462mg of PbI2 was dissolved in1mL DMF under stirring at 70∘C for 12 hours 40 120583L PbI2solution was spin-coated on the mp-TiO2 films at 3000 rpmfor 30 s After loadingwas performed for 4min the substrateswere dried at 70∘C for 30min After the films were cooled toroom temperature 90 120583L CH3NH3I solution in 2-propanol(8mgmL) was sprayed on the PbI2 films and the filmswere spun at 4000 rpm for 30 s and then dried at 70∘Cfor 30min The hole transporting layer (HTL) was preparedby spinning spiro-MeOTAD on the TiO2CH3NH3PbI3

film at 3000 rpm for 30 s Finally 70 nm gold elec-trodes were deposited on top of the device by thermallyevaporation

23 Characterization and Measurement The surface mor-phology of the films was observed with a field emission scan-ning electron microscope (SEM SU8010 Hitachi 200 kV105 120583A) The AFM images were obtained by An AC ModeIII (Agilent 5500) atomic force microscope (AFM) X-raydiffraction (XRD) patterns were obtained by using a BrukerX-ray diffractometer with a Cu-K120572 radiation source (40 kV400mA) The 2120579 diffraction angle was scanned from 10∘to 80∘ with a scanning speed of 1 second per step Theincident-photon-to-electron conversion efficiency (IPCE)curves were measured under ambient atmosphere using aQE-R measurement system (Enli Technology) The current-voltage characteristics (J-V curves) were obtained with aKeithley 2400 source meter and a sunlight simulator (XES-300T1 SAN-EI Electric AM 15) which was calibrated usinga standard silicon reference cell

3 Results and Discussion

31 Morphology of the Porous TiO2 Film The size andmass fraction of PS spheres are crucial in determining theporosity and uniformity of the TiO2 mesoporous layer Thesurface morphology of the TiO2 films was analyzed byscanning electron microscopy The SEM images of sam-ple PS-10 before and after heat treatment are shown inFigure S1 in Supplementary Material available online athttpsdoiorg10115520174935265 As observed in Figure 2unlike the TiO2 layer formed by spinning the paste withoutPS spheres (PS-0) pores can be observed in the mp-TiO2film prepared by TiO2 paste with PS spheres For a low massfraction of 05 wt PS spheres in the paste (PS-05) a fewpores with an average size of 70 nm (the statistic numbersand histogram of pore size distribution are shown in TableS1 and Figure S2) are formed on the surface of the mp-TiO2layer When the mass fraction of the PS spheres in TiO2paste increased to 10 wt (PS-10) lots of pores with anaverage size of 80 nm are formed The average pore sizes forboth PS-05 and PS-10 are almost the same and the poredistribution is uniform As the mass fraction of PS spheresincreases to 15 wt (PS-15) pores with relative larger pores(94 nm) were formed due to the high mass fraction of PSspheres and the agglomeration of PS spheres in the TiO2paste The pore distribution is inhomogeneous comparedto the PS-10 sample The pore structure could be clearlyobserved in the cross-sectional SEM images of samples PS-0and PS-10 (Figures 2(e) and 2(f)) As observed in Figures 2(e)and 2(f) the thickness of samples PS-0 and PS-10 is 260 nmand 360 nm respectively Moreover the porous structure ofsample PS-10 is looser than that of sample PS-0 The TiO2nanoparticles are densely packed and there are almost nopores among the nanoparticles in sample PS-0 Howeverpores can be observed from the cross-sectional SEM imagein PS-10 (Figure 2(f)) The pores emerged not only on thesurface of mp-TiO2 film but also throughout the film Sample


500 nm2 120583m

(a)

500 nm2 120583m

(b)

500 nm2 120583m

(c)

500 nm

2 120583m

(d)

1 120583m

(e)

1 120583m

(f)

Figure 2 Plane-view SEM images of (a) PS-0 (b) PS-05 (c) PS-10 and (d) PS-15 Cross-sectional SEM images under high magnificationof (e) PS-0 and (f) PS-10

PS-10 is thicker than sample PS-0 due to the presence ofmorepores in the film

32 Effect of TiO2 Porosity on the Growth of Perovskite Themp-TiO2 film plays a key role in determining the structure ofthe perovskite layer SEM and AFM images of the perovskitelayer were obtained for mp-TiO2 films prepared by TiO2paste with different mass fraction PS spheres As shownin Figure 3 the average size of the perovskite is 300 nmregardless of if PS spheres were used in the mp-TiO2 pasteor notThe root-mean-square (RMS) roughness values of theCH3NH3PbI3 films based on samples PS-0 PS-05 PS-10and PS-15 obtained for a 5120583m times 5 120583m area were evaluatedas 533 nm 556 nm 532 nm and 582 nm respectively Thismeans that the amount of pores in the mp-TiO2 films does

not change the morphology and roughness of the perovskitefilm

To better understand the distribution of perovskite inthe mp-TiO2 film energy dispersive X-ray (EDX) mappingwas performedThe EDXmapping of the cross-sectional areashows the distribution of two elements Ti and Pb along themp-TiO2 film thickness As observed in Figure 4(a) a smallamount of Pb is deposited in the sample PS-0 Figure 4(b)shows thatmore Pb is deposited at deeper levels in the samplePS-10 and the distribution of Pb is more uniform alongthe thickness of the TiO2 film In addition CH3NH3PbI3was uniformly distributed in the mp-TiO2 film owing to thepresence of more pores

Moreover the perovskite crystallinity and the amount ofresidual PbI2 are crucial to the performance of perovskitesolar cells It is well known that the residual PbI2 layer exists


1 120583m

(a)

00040812162024283236404448

minus120minus100minus80minus60minus40minus20020406080100120

(nm

)

Topography trace main flatten 3rd order

00

04

08

12

16

20

24

28

3236404448

(120583m)

(120583m

)

(b)

1 120583m

(c)

00040812162024283236404448

(120583m

)

00

04

08

12

16

20

24

28

3236404448

(120583m)

minus80

minus60

minus40

minus20

0

20

40

60

80

(nm

)


(d)

1 120583m

(e)

00

04

08

12

16

20

24

28

3236404448

(120583m)

00040812162024283236404448

(120583m

)


(nm

)


(f)

1 120583m

(g)

00

04

08

12

16

20

24

28

3236404448

(120583m)

00040812162024283236404448

(120583m

)

minus120minus140

minus100minus80minus60minus40minus20020406080100120

(nm

)


(h)

Figure 3 SEM and AFM images (5 120583m times 5 120583m) of the perovskite films based on the mesoporous TiO2 (a) (b) PS-0 (c) (d) PS-05 (e) (f)PS-10 and (g) (h) PS-15


SEM Ti Pb

(a)

SEM Ti Pb

(b)

Figure 4 SEM-EDXmapping along the mp-TiO2 film thickness to show the change in the distribution of Ti and Pb in CH3NH3PbI3 loadedon (a) PS-0 and (b) PS-10

between the interface of the mp-TiO2 film and perovskitelayer due to the incomplete reaction of PbI2 and CH3NH3I[26] Excessive amounts of residual PbI2 will block theelectron injected from the perovskite to mp-TiO2 film whichdeteriorates the cell performance of PSCs [27 28] Howevera trace amount of residual PbI2 acts as a passivation layerand reduces charge recombination at the interface betweenmp-TiO2 film and the perovskite layer To investigate theinfluence of the porosity of TiO2 substrate on the growth ofperovskite X-ray diffraction was performed In Figure 5 thepeaks at 268∘ 381∘ and 518∘ correspond to the (110) (200)and (211) planes of FTOThediffraction peaksmarked by starsrepresent the PbI2 (001) lattice plane which conforms wellwith the literature data [29]The Bragg peaks at 1408∘ 1992∘2840∘ 3185∘ 4046∘ and 4302∘ respectively represent thereflections from the (110) (112) (220) (310) (224) and (314)crystal planes of the tetragonal perovskite structure [3031] which means that the change in porosity of the TiO2mesoporous layer has no influence on perovskite crystallinityHowever as the mass fraction of PS spheres in the TiO2 pasteincreases the intensity of the PbI2 peaks reduces There isonly a little residual PbI2 in the sample PS-10 By introducingPS spheres in TiO2 paste more pores were formed in themp-TiO2 film The presence of more pores enables a deeperinfiltration of PbI2 and CH3NH3I solution which endowscomplete reaction to CH3NH3PbI3

33 Photovoltaic Characterization of PSCs The current den-sity versus voltage (J-V) characteristics of PCSs based on themp-TiO2 layer prepared by TiO2 paste with and without PS

lowast

lowast

(110)

(112

)

(220

)(3

10)

(224

)(3

14)

10 20 30 40 50 60

2 theta (degree)

Inte

nsity

(au

)

PbI2FTO and TiO2

15wt

10wt

05wt

0wt

Figure 5 X-ray diffraction patterns of CH3NH3PbI3 films based onTiO2 mesoporous layers with different mass fractions of PS spheres

spheres are shown in Figure 6 The photovoltaic parametersof the devices are summarized in Table 1 PSCs based onthe mp-TiO2 film PS-0 showed a reasonable PCE of 1007with an open-circuit voltage (119881oc) of 091 V a short-circuitcurrent (119869sc) of 1907mAcm2 and a fill factor (FF) of 5799A relatively higher performance was exhibited by the devicewith PS spheres After doping 05 wt PS spheres 119869sc 119881oc


00 02 04 06 08 100

4

8

12

16

20

Voltage (V)

Curr

ent d

ensit

y (m

Ac

m2)

15wt PS10wt PS05wt PS0wt PS

(a)

000 005 010 015 020 0250

10

20

30

15wt10wt05wt0wt

dVdJ

(Ωc

m2)

1(J + Jsc) (cm2mA)

(b)

Figure 6 (a) Current density-voltage curves and the best-performing solar cells based on mp-TiO2 film with different wt of PS (b) Plotsof dVdJ versus 1(119869 + 119869sc) and the linear fitting curves

Table 1 Photovoltaic performance of CH3NH3PbI3 based devices as a function of different wt of PS

wt of PS 119877sh (Ω) Rs (Ωsdotcm2) 119869sc (mAcm2) 119881oc (V) Fill factor () Efficiency ()0 1220 157 1907 091 5799 100705 3860 043 1964 094 6491 119210 5320 056 1944 093 6991 126215 3700 071 1954 090 6347 1114

FF and PCE increased to 1964mAcm2 094V 6491 and1192 respectively For a 10 mass fraction of PS spheresthe best PCE (119881oc of 093 119869sc of 1944mAcm2 FF of 6991and PCE of 1262) was achieved When the mass fractionof PS spheres increased to 15 wt the PCS exhibits 119869sc of1954mAcm2119881oc of 090V FF of 6347 and PCE of 1114Thedecrease in the residual PbI2 contributes to rapid electroninjection from the perovskite to TiO2 and higher 119869sc Theimprovements in the performance for the PSCs are mainlydue to the increase of FF Generally FF depends largely onthe series resistance (119877119904) and shunt resistance (119877sh)

The equivalent circuit of the perovskite solar cell is shownin Figure 7 The output current density 119869 can be expressed bythe following equation

119869 = 1198690 (119890119902(119881minus119869119877

119904)119860119896119879 minus 1) + 119881 minus 119869119877119904

119877shminus 119869sc (1)

where 1198690 represent the reverse saturation current density 119860is ideality factor 119896 is Boltzmannrsquos constant 119879 represent thetemperature and 119902 represent electron charge When 119877119904 ≪119877sh (1) can be expressed as

119889119881119889119869= 119877119904 +1198601198961198791199021119869 + 119869sc (2)

It is found that from (2) dVdJ has a linear relation with(119869sc minus 119869)

minus1 The intercept of the linear fitting curve gives

the value of series resistance Figure 6(b) shows the plotof dVdJ versus 1(119869 + 119869sc) and the linear fitting curveAs can be seen in Figure 6(b) the fitting curves are morelinear by doping PS spheres in TiO2 paste Slightly decreasedvalues of 119877119904 from 157Ωsdotcm2 to 043Ωsdotcm2 056Ωsdotcm2 and071Ωsdotcm2 were evaluated after doping 05 wt 10 wt and15 wt PS spheres in the mp-TiO2 paste The smaller Rsvalues are due to the reduction in both the contact resistanceand bulk resistance which means a higher photocurrent willbe generated [32] However when the mass fraction of PSspheres is 15 wt the increased Rs is attributed to the higherresistance caused bymore pores and the negative contact withTiO2 nanoparticles The device based on TiO2 mesoporouslayer prepared by TiO2 paste with PS spheres showed larger119877sh (119877sh values of the PSCs are 1220Ω 3860Ω 5320Ω and3700Ω for doping with 0wt 05 wt 10 wt and 15 wtPS spheres resp) A higher 119877sh can improve FF and electronmobility [33] which is consistent with the results of the J-Vtest119877sh is closely related to the charge recombination at

interfaces inside solar cells A lower charge recombinationcontributes to a higher 119877sh [34] To better understand theseparation of light-induced charge at the TiO2CH3NH3PbI3interface we performed time-resolved photoluminescence(PL) decay measurements on the CH3NH3PbI3 perovskite-filled mp-TiO2 films prepared by TiO2 paste with different


Load

J Rs

JDJL Rsh

+

minus

Figure 7 Equivalent circuit of the perovskite solar cell

20 30 40 50 60 70

Time (ns)

00

02

04

06

08

10

PL (n

orm

)

0wt10wt

05wt15wt

Figure 8 Normalized transient PL decay profiles of the perovskitesbased on TiO2 with different wt PS

mass fractions of PS spheres which are presented in Fig-ure 8 Using global biexponential fits the PL decay of theCH3NH3PbI3 perovskite in the mp-TiO2 films without PSspheres and with 05 wt 10 wt and 15 wt PS spheresexhibits 1205911 values of 2253 ns 1757 ns 1771 ns and 1893 nsrespectively By doping PS spheres into the TiO2 paste therate of electron injection from the perovskite into TiO2 filmbecomes faster which results in lower charge recombinationat the TiO2CH3NH3PbI3 interfacesThis could be attributedto the better filling of the CH3NH3PbI3 perovskite in themp-TiO2 film and the more complete contact between theTiO2perovskite as more pores emerge in the mp-TiO2 film

The photon-to-electron conversion efficiency (IPCE)spectra with mp-TiO2 doping for different mass fractionsof PS spheres are shown in Figure 9 The convolution ofthe spectral response with the photon flux of the AM 15Gspectrumprovided the estimated 119869sc values of 15537mAcm216994mAcm2 16825mAcm2 and 16397mAcm2 Thecalculated 119869sc values from the IPCE spectrum are wellmatched with the 119869sc values obtained from the J-V curvesIn addition the PCSs from mp-TiO2 films with PS spheresexhibited a higher and broader spectrum from 450 nmto 700 nm Here an IPCE of sim80 was obtained at the

0

20

40

60

80

IPCE

()

300 400 500 600 700 800

Wavelength (nm)

0wt PS10wt PS

05wt PS15wt PS

Figure 9 IPCE spectra of the best-performing solar cells based ondifferent mass fractions of PS spheres

maximum peak while the device based on mp-TiO2 filmswithout PS spheres exhibited a lower IPCE of sim70

To further determine the influence of the porosity of mp-TiO2 films on the fabricated solar cells we showed the statisticresults of the cells based on the mp-TiO2 film prepared byTiO2 paste with different mass fractions of PS spheres inFigure 10 The deviations of 119869sc 119881oc FF and PCE have beenshown in Table S2 As observed in Figure 10 119869sc and FFincrease as the mass fraction of the PS spheres increases andthey attain their highest values at themass fraction of 10 wtwhich contributes to the increase in the PCE

4 Conclusions

In conclusion mp-TiO2 films with tunable porosities werefabricated by doping PS spheres in TiO2 paste and appliedas the ETL of perovskite solar cells The results indicate thatthe porosity of mp-TiO2 films not only affects the infiltrationand residual amounts of PbI2 but also significantly influencesthe contact between the mp-TiO2 film and perovskite layerBy adjusting the mass fraction of PS spheres the perovskitesolar cell based onmp-TiO2 film prepared by TiO2 paste with10 wt PS spheres exhibits the highest power conversionefficiency of 1262 under a simulated standard AM 15condition

Competing Interests

The authors declare that they have no competing interests

Acknowledgments

This work was supported by the National High TechnologyResearch andDevelopment Program of China (863 Program)(no 2015AA050602) the National Natural Science Founda-tion of China (no 51372083) Jiangsu Province Science and


0 05 10 15

180

185

190

195

200

205

210

Mass fraction of PS spheres ()

J sc

(mA

cm

2)

(a)

0 05 10 15080

085

090

095

100


Voc

(V)

(b)

0 05 10 1552

56

60

64

68

72


FF (

)

(c)

0 05 10 15

9

10

11

12

13


PCE

()

(d)

Figure 10 Statistic results of the cells based on the mp-TiO2 film with different mass fractions of PS spheres

Technology Support Program China (BE2014147-4) and theFundamental Research Funds for the Central Universities(nos 2014ZZD07 and 2015ZD11)

References

[1] A Kojima K Teshima Y Shirai and TMiyasaka ldquoOrganomet-al halide perovskites as visible-light sensitizers for photovoltaiccellsrdquo Journal of the American Chemical Society vol 131 no 17pp 6050ndash6051 2009

[2] ldquoBest Research-Cell Efficiencierdquo national renewable energy lab-oratory httpwwwnrelgovpvassetsimagesefficiency chartjpg

[3] W S Yang J H Noh N J Jeon et al ldquoHigh-performance pho-tovoltaic perovskite layers fabricated through intramolecularexchangerdquo Science vol 348 no 6240 pp 1234ndash1237 2015

[4] J Qing H-T Chandran H-T Xue et al ldquoSimple fabricationof perovskite solar cells using lead acetate as lead sourceat low temperaturerdquo Organic Electronics physics materialsapplications vol 27 article no 3243 pp 12ndash17 2015

[5] M I Ahmed A Habib and S S Javaid ldquoPerovskite solar cellspotentials challenges and opportunitiesrdquo International Journalof Photoenergy vol 2015 Article ID 592308 13 pages 2015

[6] Q Chen H Zhou Z Hong et al ldquoPlanar heterojunction per-ovskite solar cells via vapor-assisted solution processrdquo Journalof the American Chemical Society vol 136 no 2 pp 622ndash6252014

[7] M Liu M B Johnston and H J Snaith ldquoEfficient planarheterojunction perovskite solar cells by vapour depositionrdquoNature vol 501 no 7467 pp 395ndash398 2013

[8] L Etgar P Gao Z Xue et al ldquoMesoscopic CH3NH3PbI3TiO2heterojunction solar cellsrdquo Journal of the American ChemicalSociety vol 134 no 42 pp 17396ndash17399 2012

[9] H-S Kim C-R Lee J-H Im et al ldquoLead iodide perovskitesensitized all-solid-state submicron thin film mesoscopic solarcell with efficiency exceeding 9rdquo Scientific Reports vol 2article 591 2012

[10] M M Lee J Teuscher T Miyasaka T N Murakami andH J Snaith ldquoEfficient hybrid solar cells based on meso-superstructured organometal halide perovskitesrdquo Science vol338 no 6107 pp 643ndash647 2012


[11] Y Li J K Cooper R Buonsanti et al ldquoFabrication of planarheterojunction perovskite solar cells by controlled low-pressurevapor annealingrdquo Journal of Physical Chemistry Letters vol 6no 3 pp 493ndash499 2015

[12] H Liu Z Huang S Wei L Zheng L Xiao and Q GongldquoNano-structured electron transporting materials for per-ovskite solar cellsrdquoNanoscale vol 8 no 12 pp 6209ndash6221 2016

[13] M He D Zheng MWang C Lin and Z Lin ldquoHigh efficiencyperovskite solar cells from complex nanostructure to planarheterojunctionrdquo Journal of Materials Chemistry A vol 2 no 17pp 5994ndash6003 2014

[14] H Lu K Deng N Yan et al ldquoEfficient perovskite solar cellsbased on novel three-dimensional TiO2 network architecturesrdquoScience Bulletin vol 61 no 10 pp 778ndash786 2016

[15] Y Yang K Ri A Mei et al ldquoThe size effect of TiO2 nanoparti-cles on a printable mesoscopic perovskite solar cellrdquo Journal ofMaterials Chemistry A vol 3 no 17 pp 9103ndash9107 2015

[16] S Aharon S Gamliel B E Cohen and L Etgar ldquoDeple-tion region effect of highly efficient hole conductor freeCH3NH3PbI3 perovskite solar cellsrdquo Physical Chemistry Chem-ical Physics vol 16 no 22 pp 10512ndash10518 2014

[17] Y Zhao A M Nardes and K Zhu ldquoSolid-state mesostructuredperovskite CH3NH3PbI3 solar cells charge transport recom-bination and diffusion lengtrdquo Journal of Physical ChemistryLetters vol 5 no 3 pp 490ndash494 2014

[18] H-S Kim and N-G Park ldquoParameters affecting IndashV hysteresisof CH3NH3PbI3 perovskite solar cells effects of perovskitecrystal size and mesoporous TiO2 layerrdquo Journal of PhysicalChemistry Letters vol 5 no 17 pp 2927ndash2934 2014

[19] A Rapsomanikis D Karageorgopoulos P Lianos and EStathatos ldquoHigh performance perovskite solar cells with func-tional highly porous TiO2 thin films constructed in ambient airrdquoSolar Energy Materials and Solar Cells vol 151 pp 36ndash43 2016

[20] W Wang Z Zhang Y Cai et al ldquoEnhanced performance ofCH3NH3PbI3minus119909Cl119909 perovskite solar cells by CH3NH3I modifi-cation of TiO2-perovskite layer interfacerdquo Nanoscale ResearchLetters vol 11 no 1 article 316 2016

[21] S Dharani H K Mulmudi N Yantara et al ldquoHigh efficiencyelectrospun TiO2 nanofiber based hybrid organicndashinorganicperovskite solar cellrdquo Nanoscale vol 6 no 3 pp 1675ndash16792014

[22] A Sarkar N J Jeon J H Noh and S I Seok ldquoWell-organizedmesoporous TiO2 photoelectrodes by block copolymer-induced solndashGel assembly for inorganicndashorganic hybridperovskite solar cellsrdquo Journal of Physical Chemistry C vol 118no 30 pp 16688ndash16693 2014

[23] Y J Kim Y H Lee M H Lee et al ldquoFormation of efficientdye-sensitized solar cells by introducing an interfacial layer oflong-range orderedmesoporous TiO2 thin filmrdquo Langmuir vol24 no 22 pp 13225ndash13230 2008

[24] J Du X Lai N Yang et al ldquoHierarchically orderedmacrominusmesoporous TiO2minusgraphene composite filmsimproved mass transfer reduced charge recombinationand their enhanced photocatalytic activitiesrdquo ACS Nano vol 5no 1 pp 590ndash596 2011

[25] C Dionigi P Greco G Ruani M Cavallini F Borgatti andF Biscarini ldquo3D hierarchical porous TiO2 films from colloidalcomposite fluidic depositionrdquo Chemistry of Materials vol 20no 22 pp 7130ndash7135 2008

[26] S Wang W Dong X Fang et al ldquoCredible evidence for thepassivation effect of remnant PbI2 in CH3NH3PbI3 films in

improving the performance of perovskite solar cellsrdquoNanoscalevol 8 no 12 pp 6600ndash6608 2016

[27] Y H Lee J Luo R Humphry-Baker P Gao M Gratzel andMK Nazeeruddin ldquoUnraveling the reasons for efficiency loss inperovskite solar cellsrdquo Advanced Functional Materials vol 25no 25 pp 3925ndash3933 2015

[28] J Jiang H J Tao S Chen et al ldquoEfficiency enhancement ofperovskite solar cells by fabricating as-prepared film beforesequential spin-coating procedurerdquoApplied Surface Science vol371 pp 289ndash295 2016

[29] D H Cao C C Stoumpos C D Malliakas et al ldquoRem-nant Pbi2 an unforeseen necessity in high-efficiency hybridperovskite-based solar cells A)rdquo APL Materials vol 2 no 9Article ID 091101 2014

[30] Y Zhao and K Zhu ldquoCharge transport and recombinationin perovskite (CH3NH3)PbI3 sensitized TiO2 solar cellsrdquo TheJournal of Physical Chemistry Letters vol 4 no 17 pp 2880ndash2884 2013

[31] T Baikie Y Fang J M Kadro et al ldquoSynthesis and crystalchemistry of the hybrid perovskite (CH3NH3)PbI3 for solid-state sensitised solar cell applicationsrdquo Journal of MaterialsChemistry A vol 1 no 18 pp 5628ndash5641 2013

[32] Y Tu J Wu M Zheng et al ldquoTiO2 quantum dots as superbcompact block layers for high-performance CH3NH3PbI3 per-ovskite solar cells with an efficiency of 1697rdquo Nanoscale vol7 no 48 pp 20539ndash20546 2015

[33] W Ke G Fang J Wan et al ldquoEfficient hole-blocking layer-free planar halide perovskite thin-film solar cellsrdquo NatureCommunications vol 6 article 6700 2015

[34] W Ke G Fang Q Liu et al ldquoLow-temperature solution-processed tin oxide as an alternative electron transporting layerfor efficient perovskite solar cellsrdquo Journal of the AmericanChemical Society vol 137 no 21 pp 6730ndash6733 2015

Submit your manuscripts athttpswwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Inorganic ChemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

International Journal ofPhotoenergy


Carbohydrate Chemistry

International Journal of


Journal of

Chemistry


Advances in

Physical Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2014

Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

SpectroscopyInternational Journal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of


Chromatography Research International


Applied ChemistryJournal of



Theoretical ChemistryJournal of


Journal of

Spectroscopy

Analytical ChemistryInternational Journal of


Journal of


Quantum Chemistry


Organic Chemistry International

ElectrochemistryInternational Journal of



CatalystsJournal of


FTO glass FTO glass FTO glass

Compact TiO2Compact TiO2 Compact TiO2

TiO2

PbI2PbI2

CH3NH3PbI3

(a)

FTO glass FTO glass FTO glassFTO glass

PS

ThermaltreatmentCompact TiO2 Compact TiO2

Compact TiO2 Compact TiO2

TiO2TiO2

PbI2CH3NH3PbI3

(b)

Figure 1 Schematic illustration of the distribution of PbI2 and TiO2 in mp-TiO2 film (a) without and (b) with PS spheres

infiltration is thought as an effective way to decrease thecontact barrier between the TiO2CH3NH3PbI3 interfaceswhich could improve the transport of carriers in thePSCs Dharani et al [21] used electrospinning to prepareTiO2 nanofibers as the ETL for PSCs The TiO2 nanofiberformed a highly porous structure The excellent porousnetwork resulted in improved loading of PbI2 Therefore theCH3NH3I can infiltrate through the pores to completely reactwith PbI2 Sarkar et al [22] prepared well-organized meso-porous TiO2 photoelectrodes with enlarged pores by blockcopolymer-induced solminusgel assembly TiO2 photoelectrodeswith larger pores are favorable for filling of perovskite in themp-TiO2 filmWithin a certain range devices based on largerpores showed a higher 119869sc and superior performance Rap-somanikis et al [19] synthesized highly meso-macroporousTiO2 thin films as ETLs of PSCs using a solndashgel process andPluronic P-123 block copolymer as the organic templateTheirresults showed that the high porosity enabled the TiO2 thinfilm to act as an ideal host for perovskiteThe efficient contactbetween mp-TiO2 and perovskite enhanced the electrontransport

Methods of controlling the mesoporous networks of mp-TiO2 include changing the size of TiO2 nanoparticles usingamphiphilic block copolymers [14 22] and using templatesMany researchers reported that polystyrene (PS) spheres canbe used as a mesostructured template to fabricate macroand mesoporous TiO2 films in dye-sensitized solar cells(DSSC) because of its size tunability [23 24] By using variouspreparation method and PS spheres with different sizes themorphology of the films can be easily controlled Dionigiet al [25] used PS spheres as structure-directing agents andcoated the PS spheres with titanium dihydroxide to fabricateporous TiO2 films with ordered pore architectures Du etal [24] fabricated hierarchically ordered macro-mesoporousTiO2 films as the interfacial layer of DSSC using PS spheres

as a template Because of the periodically ordered structureand large specific surface of the macro-mesoporous TiO2films a higher 119869sc and a PCE enhanced by 83 wereobtained

However to our knowledge there have been no reportson the use of PS spheres to change the mesoporous net-works of mp-TiO2 film in PSCs In this study we presenta facile method of controlling the porosity of mp-TiO2 byintroducing PS spheres into TiO2 paste which can be aneffective strategy for the development of mesoporous PSCsFigure 1 shows the schematic representation of the reactionprocess studied in this work As shown in Figure 1(a) TiO2nanoparticles are close to each otherThere are only few poresbetween the particles PbI2 cannot fully infiltrate into thenarrow pores of mp-TiO2 without the introduction of PSspheres during the preparation process instead CH3NH3Iwould react with the superficial PbI2 which results in a largeamount of residual PbI2 in the TiO2 film In Figure 1(b)PS spheres can be observed in the TiO2 film before heattreatment Then PS spheres were removed by heat treatmentand a large amount of pores were formed in mesoporousTiO2 film Therefore more PbI2 infiltrated into the filmThe subsequently deposited CH3NH3I reacted more com-pletely with PbI2 which reduced the amount of the residualPbI2 By adjusting the mass fraction of PS spheres in TiO2paste a controllable porous mp-TiO2 film was obtainedThe incorporation of the macropores in mp-TiO2 filmsincreased the perovskite loading in the film and improvedthe contact between the TiO2 and perovskite interface whicheffectively suppressed charge recombination in the interfaceX-ray diffraction and fluorescence lifetime measurementsconfirmed that the increased porosity ensured an adequatereaction between PbI2 and CH3NH3I thus decreasing theamount of residual PbI2 and enhancing the electron injectionfrom the perovskite to mp-TiO2 film The PSCs with the












500 nm2 120583m

(a)

500 nm2 120583m

(b)

500 nm2 120583m

(c)

500 nm

2 120583m

(d)

1 120583m

(e)

1 120583m

(f)








1 120583m

(a)

00040812162024283236404448


(nm

)


00

04

08

12

16

20

24

28

3236404448

(120583m)

(120583m

)

(b)

1 120583m

(c)

00040812162024283236404448

(120583m

)

00

04

08

12

16

20

24

28

3236404448

(120583m)

minus80

minus60

minus40

minus20

0

20

40

60

80

(nm

)


(d)

1 120583m

(e)

00

04

08

12

16

20

24

28

3236404448

(120583m)

00040812162024283236404448

(120583m

)


(nm

)


(f)

1 120583m

(g)

00

04

08

12

16

20

24

28

3236404448

(120583m)

00040812162024283236404448

(120583m

)

minus120minus140


(nm

)


(h)



SEM Ti Pb

(a)

SEM Ti Pb

(b)




lowast

lowast

(110)

(112

)

(220

)(3

10)

(224

)(3

14)

10 20 30 40 50 60

2 theta (degree)

Inte

nsity

(au

)

PbI2FTO and TiO2

15wt

10wt

05wt

0wt




00 02 04 06 08 100

4

8

12

16

20

Voltage (V)

Curr

ent d

ensit

y (m

Ac

m2)


(a)

000 005 010 015 020 0250

10

20

30

15wt10wt05wt0wt

dVdJ

(Ωc

m2)

1(J + Jsc) (cm2mA)

(b)






119869 = 1198690 (119890119902(119881minus119869119877

119904)119860119896119879 minus 1) + 119881 minus 119869119877119904

119877shminus 119869sc (1)


119889119881119889119869= 119877119904 +1198601198961198791199021119869 + 119869sc (2)






Load

J Rs

JDJL Rsh

+

minus


20 30 40 50 60 70

Time (ns)

00

02

04

06

08

10

PL (n

orm

)

0wt10wt

05wt15wt




0

20

40

60

80

IPCE

()

300 400 500 600 700 800

Wavelength (nm)

0wt PS10wt PS

05wt PS15wt PS




4 Conclusions


Competing Interests


Acknowledgments



0 05 10 15

180

185

190

195

200

205

210


J sc

(mA

cm

2)

(a)

0 05 10 15080

085

090

095

100


Voc

(V)

(b)

0 05 10 1552

56

60

64

68

72


FF (

)

(c)

0 05 10 15

9

10

11

12

13


PCE

()

(d)



References














































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of












500 nm2 120583m

(a)

500 nm2 120583m

(b)

500 nm2 120583m

(c)

500 nm

2 120583m

(d)

1 120583m

(e)

1 120583m

(f)








1 120583m

(a)

00040812162024283236404448


(nm

)


00

04

08

12

16

20

24

28

3236404448

(120583m)

(120583m

)

(b)

1 120583m

(c)

00040812162024283236404448

(120583m

)

00

04

08

12

16

20

24

28

3236404448

(120583m)

minus80

minus60

minus40

minus20

0

20

40

60

80

(nm

)


(d)

1 120583m

(e)

00

04

08

12

16

20

24

28

3236404448

(120583m)

00040812162024283236404448

(120583m

)


(nm

)


(f)

1 120583m

(g)

00

04

08

12

16

20

24

28

3236404448

(120583m)

00040812162024283236404448

(120583m

)

minus120minus140


(nm

)


(h)



SEM Ti Pb

(a)

SEM Ti Pb

(b)




lowast

lowast

(110)

(112

)

(220

)(3

10)

(224

)(3

14)

10 20 30 40 50 60

2 theta (degree)

Inte

nsity

(au

)

PbI2FTO and TiO2

15wt

10wt

05wt

0wt




00 02 04 06 08 100

4

8

12

16

20

Voltage (V)

Curr

ent d

ensit

y (m

Ac

m2)


(a)

000 005 010 015 020 0250

10

20

30

15wt10wt05wt0wt

dVdJ

(Ωc

m2)

1(J + Jsc) (cm2mA)

(b)






119869 = 1198690 (119890119902(119881minus119869119877

119904)119860119896119879 minus 1) + 119881 minus 119869119877119904

119877shminus 119869sc (1)


119889119881119889119869= 119877119904 +1198601198961198791199021119869 + 119869sc (2)






Load

J Rs

JDJL Rsh

+

minus


20 30 40 50 60 70

Time (ns)

00

02

04

06

08

10

PL (n

orm

)

0wt10wt

05wt15wt




0

20

40

60

80

IPCE

()

300 400 500 600 700 800

Wavelength (nm)

0wt PS10wt PS

05wt PS15wt PS




4 Conclusions


Competing Interests


Acknowledgments



0 05 10 15

180

185

190

195

200

205

210


J sc

(mA

cm

2)

(a)

0 05 10 15080

085

090

095

100


Voc

(V)

(b)

0 05 10 1552

56

60

64

68

72


FF (

)

(c)

0 05 10 15

9

10

11

12

13


PCE

()

(d)



References














































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


500 nm2 120583m

(a)

500 nm2 120583m

(b)

500 nm2 120583m

(c)

500 nm

2 120583m

(d)

1 120583m

(e)

1 120583m

(f)








1 120583m

(a)

00040812162024283236404448


(nm

)


00

04

08

12

16

20

24

28

3236404448

(120583m)

(120583m

)

(b)

1 120583m

(c)

00040812162024283236404448

(120583m

)

00

04

08

12

16

20

24

28

3236404448

(120583m)

minus80

minus60

minus40

minus20

0

20

40

60

80

(nm

)


(d)

1 120583m

(e)

00

04

08

12

16

20

24

28

3236404448

(120583m)

00040812162024283236404448

(120583m

)


(nm

)


(f)

1 120583m

(g)

00

04

08

12

16

20

24

28

3236404448

(120583m)

00040812162024283236404448

(120583m

)

minus120minus140


(nm

)


(h)



SEM Ti Pb

(a)

SEM Ti Pb

(b)




lowast

lowast

(110)

(112

)

(220

)(3

10)

(224

)(3

14)

10 20 30 40 50 60

2 theta (degree)

Inte

nsity

(au

)

PbI2FTO and TiO2

15wt

10wt

05wt

0wt




00 02 04 06 08 100

4

8

12

16

20

Voltage (V)

Curr

ent d

ensit

y (m

Ac

m2)


(a)

000 005 010 015 020 0250

10

20

30

15wt10wt05wt0wt

dVdJ

(Ωc

m2)

1(J + Jsc) (cm2mA)

(b)






119869 = 1198690 (119890119902(119881minus119869119877

119904)119860119896119879 minus 1) + 119881 minus 119869119877119904

119877shminus 119869sc (1)


119889119881119889119869= 119877119904 +1198601198961198791199021119869 + 119869sc (2)






Load

J Rs

JDJL Rsh

+

minus


20 30 40 50 60 70

Time (ns)

00

02

04

06

08

10

PL (n

orm

)

0wt10wt

05wt15wt




0

20

40

60

80

IPCE

()

300 400 500 600 700 800

Wavelength (nm)

0wt PS10wt PS

05wt PS15wt PS




4 Conclusions


Competing Interests


Acknowledgments



0 05 10 15

180

185

190

195

200

205

210


J sc

(mA

cm

2)

(a)

0 05 10 15080

085

090

095

100


Voc

(V)

(b)

0 05 10 1552

56

60

64

68

72


FF (

)

(c)

0 05 10 15

9

10

11

12

13


PCE

()

(d)



References














































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


1 120583m

(a)

00040812162024283236404448


(nm

)


00

04

08

12

16

20

24

28

3236404448

(120583m)

(120583m

)

(b)

1 120583m

(c)

00040812162024283236404448

(120583m

)

00

04

08

12

16

20

24

28

3236404448

(120583m)

minus80

minus60

minus40

minus20

0

20

40

60

80

(nm

)


(d)

1 120583m

(e)

00

04

08

12

16

20

24

28

3236404448

(120583m)

00040812162024283236404448

(120583m

)


(nm

)


(f)

1 120583m

(g)

00

04

08

12

16

20

24

28

3236404448

(120583m)

00040812162024283236404448

(120583m

)

minus120minus140


(nm

)


(h)



SEM Ti Pb

(a)

SEM Ti Pb

(b)




lowast

lowast

(110)

(112

)

(220

)(3

10)

(224

)(3

14)

10 20 30 40 50 60

2 theta (degree)

Inte

nsity

(au

)

PbI2FTO and TiO2

15wt

10wt

05wt

0wt




00 02 04 06 08 100

4

8

12

16

20

Voltage (V)

Curr

ent d

ensit

y (m

Ac

m2)


(a)

000 005 010 015 020 0250

10

20

30

15wt10wt05wt0wt

dVdJ

(Ωc

m2)

1(J + Jsc) (cm2mA)

(b)






119869 = 1198690 (119890119902(119881minus119869119877

119904)119860119896119879 minus 1) + 119881 minus 119869119877119904

119877shminus 119869sc (1)


119889119881119889119869= 119877119904 +1198601198961198791199021119869 + 119869sc (2)






Load

J Rs

JDJL Rsh

+

minus


20 30 40 50 60 70

Time (ns)

00

02

04

06

08

10

PL (n

orm

)

0wt10wt

05wt15wt




0

20

40

60

80

IPCE

()

300 400 500 600 700 800

Wavelength (nm)

0wt PS10wt PS

05wt PS15wt PS




4 Conclusions


Competing Interests


Acknowledgments



0 05 10 15

180

185

190

195

200

205

210


J sc

(mA

cm

2)

(a)

0 05 10 15080

085

090

095

100


Voc

(V)

(b)

0 05 10 1552

56

60

64

68

72


FF (

)

(c)

0 05 10 15

9

10

11

12

13


PCE

()

(d)



References














































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


SEM Ti Pb

(a)

SEM Ti Pb

(b)




lowast

lowast

(110)

(112

)

(220

)(3

10)

(224

)(3

14)

10 20 30 40 50 60

2 theta (degree)

Inte

nsity

(au

)

PbI2FTO and TiO2

15wt

10wt

05wt

0wt




00 02 04 06 08 100

4

8

12

16

20

Voltage (V)

Curr

ent d

ensit

y (m

Ac

m2)


(a)

000 005 010 015 020 0250

10

20

30

15wt10wt05wt0wt

dVdJ

(Ωc

m2)

1(J + Jsc) (cm2mA)

(b)






119869 = 1198690 (119890119902(119881minus119869119877

119904)119860119896119879 minus 1) + 119881 minus 119869119877119904

119877shminus 119869sc (1)


119889119881119889119869= 119877119904 +1198601198961198791199021119869 + 119869sc (2)






Load

J Rs

JDJL Rsh

+

minus


20 30 40 50 60 70

Time (ns)

00

02

04

06

08

10

PL (n

orm

)

0wt10wt

05wt15wt




0

20

40

60

80

IPCE

()

300 400 500 600 700 800

Wavelength (nm)

0wt PS10wt PS

05wt PS15wt PS




4 Conclusions


Competing Interests


Acknowledgments



0 05 10 15

180

185

190

195

200

205

210


J sc

(mA

cm

2)

(a)

0 05 10 15080

085

090

095

100


Voc

(V)

(b)

0 05 10 1552

56

60

64

68

72


FF (

)

(c)

0 05 10 15

9

10

11

12

13


PCE

()

(d)



References














































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


00 02 04 06 08 100

4

8

12

16

20

Voltage (V)

Curr

ent d

ensit

y (m

Ac

m2)


(a)

000 005 010 015 020 0250

10

20

30

15wt10wt05wt0wt

dVdJ

(Ωc

m2)

1(J + Jsc) (cm2mA)

(b)






119869 = 1198690 (119890119902(119881minus119869119877

119904)119860119896119879 minus 1) + 119881 minus 119869119877119904

119877shminus 119869sc (1)


119889119881119889119869= 119877119904 +1198601198961198791199021119869 + 119869sc (2)






Load

J Rs

JDJL Rsh

+

minus


20 30 40 50 60 70

Time (ns)

00

02

04

06

08

10

PL (n

orm

)

0wt10wt

05wt15wt




0

20

40

60

80

IPCE

()

300 400 500 600 700 800

Wavelength (nm)

0wt PS10wt PS

05wt PS15wt PS




4 Conclusions


Competing Interests


Acknowledgments



0 05 10 15

180

185

190

195

200

205

210


J sc

(mA

cm

2)

(a)

0 05 10 15080

085

090

095

100


Voc

(V)

(b)

0 05 10 1552

56

60

64

68

72


FF (

)

(c)

0 05 10 15

9

10

11

12

13


PCE

()

(d)



References














































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


Load

J Rs

JDJL Rsh

+

minus


20 30 40 50 60 70

Time (ns)

00

02

04

06

08

10

PL (n

orm

)

0wt10wt

05wt15wt




0

20

40

60

80

IPCE

()

300 400 500 600 700 800

Wavelength (nm)

0wt PS10wt PS

05wt PS15wt PS




4 Conclusions


Competing Interests


Acknowledgments



0 05 10 15

180

185

190

195

200

205

210


J sc

(mA

cm

2)

(a)

0 05 10 15080

085

090

095

100


Voc

(V)

(b)

0 05 10 1552

56

60

64

68

72


FF (

)

(c)

0 05 10 15

9

10

11

12

13


PCE

()

(d)



References














































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


0 05 10 15

180

185

190

195

200

205

210


J sc

(mA

cm

2)

(a)

0 05 10 15080

085

090

095

100


Voc

(V)

(b)

0 05 10 1552

56

60

64

68

72


FF (

)

(c)

0 05 10 15

9

10

11

12

13


PCE

()

(d)



References














































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










Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of

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