The subject of the current study is a concoct of anatase and rutile mixed phase titania synthesized at
40 C and
10 C. At these sub-zero temperatures, highly crystalline, phase-oriented nanostructured titania were formed. At
40 C, nanocrystals of TiO2 consist of the anatase phase while nanorods dominated by the rutile phase form at
10 C. These samples are remarkable photoanode materials with excellent photon scattering ability in dyesensitized solar cells (DSSCs). On performance optimization of DSSCs, a composition of 0.5 wt% TiO2 (prepared at
40 C) and P25 improved the photon harvesting by providing a large number of sites for interaction, resulting in a high photocurrent of 18.46 mA cm
2 and 8.6% photoconversion efficiency.

1. High-performance dye-sensitized solar cell using
dimensionally controlled titania synthesized at sub-
zero temperatures†
Kiran P. Shejale, Devika Laishram and Rakesh K. Sharma*
The subject of the current study is a concoct of anatase and rutile mixed phase titania synthesized at 40
C and
10
C. At these sub-zero temperatures, highly crystalline, phase-oriented nanostructured titania were formed.
At 40
C, nanocrystals of TiO2 consist of the anatase phase while nanorods dominated by the rutile phase form
at 10
C. These samples are remarkable photoanode materials with excellent photon scattering ability in dye-
sensitized solar cells (DSSCs). On performance optimization of DSSCs, a composition of 0.5 wt% TiO2 (prepared
at 40
C) and P25 improved the photon harvesting by providing a large number of sites for interaction, resulting
in a high photocurrent of 18.46 mA cm 2
and 8.6% photoconversion efficiency.
Introduction
Nanocrystalline TiO2 is one of the most studied low-cost, non-toxic
and stable wideband semiconducting materials. It exhibits
a broad range of unique optical, electrical and photocatalytic
properties, which are mainly governed by its morphology and
phase.1–5
This allows for a wide variety of application in the areas of
gas sensors, paints, catalysis, optics, dielectric materials,
pigments, solar cells and inorganic membranes.6–8
Among these,
the use of TiO2 in DSSCs attracted considerable attention when
Gratzel and coworkers reported a DSSC with 7% photoconversion
efficiency, followed by numerous studies to understand the
working principle behind the electrochemical solar cell.9–12
With
advancements made in DSSC, TiO2 became one of the most
investigated and sought aer material for photoanode applica-
tions. Out of many factors, structural and physical properties of
TiO2 play most crucial role in DSSC performance,13,14
governed by
crystal size, morphology, composition, porosity and surface area.15
Tuning and modication in these properties at nanoscale titania
expected to be a promising strategy to improve photo current
density in DSSC applications. Signicant efforts have been made
towards structural optimization of TiO2 photoanode such as
particle size, hierarchical, 1D–3D, hollow structures, aggregates
and micro-sized spheres,16,17
and it was observed that crystalline
size, morphology and phase composition have profound effect on
the light scattering property to harvest more photon, dye loading,
recombination properties and electron transport in DSSCs, they
have received extensive attention, and shown improved perfor-
mance of the DSSCs.18,19
Crystalline TiO2 is found as three polymorphs in nature –
anatase, rutile and brookite phase.20
Synthetically, anatase
crystalline phase is prepared at mild thermal treatment below
400
C, whereas rutile forms at a higher temperature.21
Various
strategies have been employed such as annealing, doping and
physical mixing to modify structural and physical properties of
titania.22–24
Historically titania is prepared in highly acidic/basic
condition or at high temperature that make these processes
cumbersome at large scale, accompanied with undesirable
phase transformations that limits their applications.25–27
These
synthetic limitations are noteworthy to obtain functional nano-
TiO2. A simple but perspicacious change in synthetic tempera-
ture could lead to thermodynamically controlled growth of
nanoparticle of TiO2, particularly at low temperature. Most
oen low temperature studies are carried out in room temper-
ature with a few exceptions going low as 4
C, where TiO2
hydrosols were obtained by reuxing titanium ethoxide [entry
30 from Table A2, ESI†], lately, the rst investigation on
synthesis of nano-titania at sub-zero temperature has been re-
ported by Sharma and coworkers.28
The detailed low tempera-
ture crystallization of TiO2 with their crystalline phase are
mentioned in Table S2, ESI.†
In our recent work, we have reported a simple one step, sub-
zero temperature method to synthesize well crystallized anatase
and rutile nanoparticles with controlled size and shape.28
Synergetic effect between the phase composition and variation
in shape and size of TiO2 nanoparticles was demonstrated. In
this study, two temperatures were selected based on two distinct
reasons, rst, the TiO2 synthesized at 40
C and 10
C clearly
point towards drastic changes in texture and phase combina-
tion. Second, the band gap of both the samples were found to
have signicant difference and expected to have better light
harvesting in DSSC (Fig. S1, ESI†). The factors affecting the
morphology of the synthesized TiO2 nanoparticles at low
Department of Chemistry, Indian Institute of Technology Jodhpur, Jodhpur, 342011,
India. E-mail: rks@iitj.ac.in
† Electronic supplementary information (ESI) available. See DOI:
10.1039/c6ra00227g
Cite this: RSC Adv., 2016, 6, 23459
Received 5th January 2016
Accepted 21st February 2016
DOI: 10.1039/c6ra00227g
www.rsc.org/advances
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2. temperature have been explored and the collaborative role of
the mixed phase and different size with shape have been
analyzed using them as photoanode material in DSSC.
Experimental section
Materials
Titanium(IV) isopropoxide (TTIP) and titanium tetrachloride
(TiCl4) (99%) were purchased from Spectrochem. Hydrochloric
acid (37%) and nitric acid (68–70%) were acquired from Fisher
Scientic. Ethanol (absolute 99.8%), terpineol (98%), acetic
acid (glacial 96%) and ethyl cellulose (44–51%) were obtained
from Changshu Yangyuan, Alfa Aesar, Qualigens and Himedia
respectively. P25 commercial TiO2 nanoparticles was purchased
from Degussa. Fluorine doped tin oxide (FTO) glass, electrolyte
solution Iodolyte Z-50, Meltonix (Surlyn), Platisol-T and N719
Ruthenizer 535-bis TBA were purchased from Solaronix. Silver
conductive paste (Pelco-colloidal Silver liquid) was acquired
from Ted Pella, Inc.
TiO2 synthesis
TiO2 nanoparticles of different morphologies and size were
prepared using reactor chamber (Radley). Overhead stirrer
mounted on the reactor (Heldoph RZR 2102 control) was used
to maintain the stirring speed at 350 rpm. The thermoregulator
(Huber unistat 705) was connected to the reactor ready chamber
to obtain the desired reaction temperature. By controlling the
reaction temperatures at 40
C and 10
C, mixture of 80 mL
TTIP, 1000 mL ethanol and 400 mL distilled water were stirred
for 24 hours in the reactor. Nitric acid was used to control
reaction pH up to 1.5. The resultant solution was dried and
annealed at 100
C for 12 hours. To optimize results, three
samples S1, S2 and S3 were prepared consisting of 0%, 40% and
100% of TiO2 prepared at 40
C and the remaining amount
was made up with TiO2 prepared at 10
C that is 100%, 60%
and 0% respectively.
Preparation of electrodes and device fabrication
Photoanode. FTO glass slides were ultrasonically cleaned for
15 min individually with soap solution, D/W, 0.1% HCl–ethanol
and acetone. The cleaned FTO were treated with 40 mM aqueous
TiCl4 solution at 70
C for 30 min then washed with D/W and
ethanol. Photoanodes were fabricated by screen printing method
keeping the area of the photoanode lm precisely controlled by
screen printing mesh size dimension. The prepared samples were
mixed with P25 at a ratio 4 : 6 (weight ratio) using which screen
printing paste was prepared with the addition of ethanol,
terpineol, acetic acid and ethyl cellulose. The printing process was
repeated several times to get the desired lm thickness. Firstly
sintered at 500
C for 15 min and aer post treating with 40 mM
TiCl4 aqueous solution for 30 min at 70
C, the photoanodes were
sintered again at 520
C for 30 min. The sample photoanodes
were then immersed into 0.5 mM N719 dye for 20 hours.
Counter electrode. FTO glass slides were cleaned by the same
process as mentioned earlier. Pt counter electrode were
prepared by brush painting Platisol-T onto the FTO. Then the
lms were annealed at 450
C for 30 min.
Device assembly. The dye loaded photoanode and counter
electrode were assembled into a sandwich type of structure and
aer that sealed with 25 mm thick spacer made up of Surlyn.
Then the cell was thermally treated at 110
C for 30 min. Aer
sealing, few drops of electrolyte Iodolyte Z-50 were added to ll
the space between two electrodes. Silver conductive paste was
applied on both sides of the cell and then dried at room
temperature.
Characterization
Powder X-ray diffraction (XRD) analysis of the prepared samples
were performed using Bruker D8 Advance diffractometer
equipped with Cu Ka radiation having 1.54
A wavelength Bruker
AXS (11/03-2370) as source and Bruker (C79298-A3178-A15) as
detector. Raman spectra of both samples were performed at
room temperature using Renishaw instruments with an emis-
sion wavelength of 514 nm. Scanning electron microscope
(SEM) micrograph of the TiO2 lm as photoanode was analysed
by the Zeiss EVO 18 Special Edition microscope. Transmission
electron microscope (TEM) images of the samples were ob-
tained by a FEI Tecnai-G2 T20 operated at 200 kV. The photo-
anode lm surfaces was examined by Park System XE-70 atomic
force microscope (AFM). The diffuse reectance spectra of both
samples and all the photoanodes were carried out by UV-visible
spectrophotometer (Varian Cary 4000) using diffuse reectance
spectroscopy accessory over a wavelength range of 200–800 nm.
And same instrument was used to calculate the amount of
eluted N719 dye quantity adsorbed on all the photoanodes. The
dye loaded photoanodes were dipped in 6 mL of 10 mM NaOH
in distilled water for 30 min. The current density–voltage and
electrochemical impedance spectroscopy (EIS) measurements
were recorded by an electrochemical work station CHI660E-CH
Instruments Inc. under one sun irradiation by SS50AAA solar
simulator model from PET Photo Emission Tech., Inc. Electro-
chemical impedance study of the cells were also recorded at
1 Hz to 0.1 MHz.
Results and discussion
A pervasive work was done to synthesize TiO2 with controlled
size and morphology as demonstrated in Fig. 1a. Briey, the
reaction was carried out using titanium isopropoxide precursor
in ethanol and deionized water at controlled temperatures of
40
C and 10
C as illustrated by the schematic in Fig. 1a.
The morphologies of TiO2 prepared at 40
C and 10
C were
characterized by XRD as shown in Fig. 1b and c. Interestingly,
the peaks in Fig. 1b are broader as compared to Fig. 1c which
indicates the formation of small size particle. The diffraction
peaks at 25.3 and 27.5 are assigned to (101) and (110) planes
and are matching with JCPDS reference spectra of TiO2 anatase
21-1271 (tetragonal) and TiO2 rutile 21-1276 (tetragonal) as
shown in Fig. 1b and c respectively. The XRD patterns of TiO2
prepared at 10
C and 40
C indicate change in the size and
phase percentile in the product.
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3. TiO2 prepared at 40
C display Raman active peaks having
highest intensity peak (eg) at 150 cm 1
and other peaks (a1g, eg
and 2b1g) suggesting towards high percentage of anatase phase
as shown in Fig. 1d. However in Fig. 1e, the TiO2 sample
prepared at 10
C conrms the high percentage of rutile phase
showing (eg and a1g) Raman active peaks at 443 cm 1
and 608
cm 1
respectively. The peak at 254 cm 1
is due to multiple
phonon scattering process known as compound vibrational
peak.29–31
The strain present on the grain boundaries, oxygen
vacancies, temperature, particle size etc. are known to directly
inuence the Raman peaks.32
A small shi in band positions
might be due to phonon connement, lattice strain, crystalline
size and oxygen defects.33
The crystallographic phases of both
TiO2 analyzed by Raman spectroscopy are in accordance with
the above XRD ndings and revealed the presence of both
anatase and rutile crystallographic phases in both the samples.
The detailed information of anatase and rutile crystallographic
Raman phases is provided in Note S1, ESI.† Using diffraction
peak intensities of rutile (110) and anatase (101), the weight
percentage of rutile was estimated to be 73% and 42% for
samples prepared at 10
C and 40
C respectively (see Note
S2, ESI†). Broad diffraction peaks of both samples were indi-
cating towards small size particles accompanied with defects
around their grain boundaries. These defects generate strain in
the grain boundaries which have a direct impact on the growth
of the nanoparticles.34,35
The lattice strain present at the grain
boundary along with particle size (D) are calculated for the
samples using diffraction peaks of linearly tted graphs with
b cos q/l as X-axis and sin q/l as Y-axis as shown in Fig. S2, Note
S3, ESI† and Table 1. High lattice strain, 0.0367, at 40
C is
a result of more number of atoms accompanied with defects in
the grain boundary. The change in phase combination is
determined by interface nucleation and these two factors
produces stress on the grain boundaries.36
At 10
C, lattice
strain decreasing to 0.0323 indicate towards reduced grain
boundary defects and accelerates the growth thereby forming
bigger size particle. The reaction temperature increases reduced
defects at grain boundary results in the formation of rutile
phase in the sample.
Fig. 1 (a) Schematic demonstration of TiO2 synthesis process. (b) and (c) XRD spectra of synthesized TiO2 at 40
C and 10
C respectively
along with bar line graphs shows the XRD spectra of rutile and anatase TiO2 JCPDS data. (d) and (e) Raman spectra for TiO2 synthesized at 40
C
and 10
C respectively with a 532 nm wavelength diode laser respectively.
Table 1 Morphological and optical parameters of TiO2 nanoparticles synthesized at 40
C and 10
C
TiO2 synthesis
temperatures (
C)
Weight% of
anatase
Crystallite size from
WH plot (nm)
Particle size from
TEM (nm)
Lattice
strain
Band gap
(eV)
40 58 4.4 3.78 0.0367 3.02
10 27 13.8 4.59 16.54a
0.0323 2.97
a
Dimension of nanorods are in width height.
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4. TEM analysis was carried out to conrm the size and
morphology of the TiO2 prepared at 40
C and 10
C (see
Fig. 2a and b and Table 1). TiO2 synthesized at 40
C was
found to be oval in shape with 3.78 nm as average particle size
whereas at 10
C nanoparticle was in rod shape exhibit
average width as 4.59 nm with 16.54 nm in length. Fig. 2c and
d are the HRTEM image of 40
C and 10
C showing inter
planar distance with anatase and rutile as dominating phase,
respectively. Respective dominating phases were also observed
in SAED pattern of 40
C and 10
C shown in Fig. 2e and f
respectively. Small crystal nuclei of both TiO2 structure will
form depending on the surrounding temperature.37–40
At 40
C
and 10
C, difference in the particles size and shape originates
from crystal structure consisting different arrangement in TiO6
octahedral units; anatase (zigzag packing) and rutile (linear
packing) shown in Fig. 3.41
In anatase, cis-coordination and in
rutile trans-coordination sites of octahedra are used for crystal
growth. Some have reported that the phase and shape of the
TiO2 nanoparticles formed from crystal growth are governed by
anions and solvents.42–44
As temperature increases, the thermal
conditions are able to form closest linear packing of the TiO6
octahedral units.45
In our case as shown schematically in Fig. 3,
at transition initiation temperature of 10
C, mostly rutile
crystals are formed indicating that nucleation is relatively
slower than the growth rate thus forming rod shaped nano-
particles with linearly packed TiO6 octahedral units which
exhibits less strain (0.0323, see ESI Fig. S2†) on the particles.
Where at 40
C, growth occurs simultaneously with fast
nucleation leading to anatase phase with zigzag packed crystal
structure as also reected from high strain (0.0367, see ESI
Fig. S2†) on the particle surface. This probably explains the
formation of nanorods and nanocrystals with phase transition
from anatase to rutile at sub-zero synthesis temperatures.
The optical band gap of both TiO2 samples mentioned in
Table 1 were estimated by Tauc plot and Kubelka–Munk
expression using % reectance values.46,47
Fig. 4 with inset
demonstrates % R and band gap analysis respectively. Reaction
temperature increases from 40
C to 10
C, increment of the
rutile% were reported in samples allow narrowing band gap
from 3.02 to 2.97 eV respectively. These change was also
induced by the nucleation, growth rate and stress present on the
grain boundaries which were produced by defects and particle
size.48
If these samples will be used as photoanodes in DSSC,
wider band gap will reduce recombination in the DSSC allowing
more electrons to jump from the excited state of the dye to the
conduction band of TiO2.
Fig. 2 (a) and (b) TEM images, (c) and (d) HRTEM images with marked
inter planar distance and (e) and (f) are SAED pattern of 40
C and
10
C respectively. Dotted lines in (e) and (f) are guide to eye.
Fig. 3 Schematic illustration of TiO2 synthesis process.
Fig. 4 Percentage reflectance data of TiO2 synthesized at 10
C and
40
C. And inset shows hn and (hnF(RN))(1/2)
plot.
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5. To optimize DSSC performance, three samples S1, S2 and S3
were prepared with 0, 16 and 40 of wt% of TiO2 prepared at 40
C in respective samples, the detailed composition is illustrated
in the form of a bargraph in Fig. 5a. The lm surface
morphology and the average root mean square roughness (Rrms)
of S1, S2 and S3 samples are shown in the Fig. S3, ESI† and are
listed in Table 2. The lms show columnar microstructure
accompanied by spherical grain structure suggesting that it
constitutes nanorods with oval shaped nanoparticles.
The cross sectional lm morphology was obtained by SEM
(Fig. 5b), the average thickness of the lm was found to be
14.5 mm. The lm thickness is optimized in the range of 10–18
mm range and its uniformity are the main parameters which
control the reproducibility of the DSSC performance. Above this
range, thickness produces resistance to electrons travelling
through TiO2 and also decreases the number of photons
encountered by dye molecules. Below the optimized range
number of anchoring site for dye molecules reduces. The inset of
Fig. 5b shows uniformly distributed samples along the photo-
anode lms with a highly porous structure.
Light scattering property of photoanode lms is one of the
important attributers in light harvesting efficiency of the
DSSC.49,50
The diffused reectance of S3 lm is higher as
compared to the other photoanode lms before dye loading as
shown in Fig. 5c. High percentage of anatase having different
sized nanoparticles with higher surface roughness attributes to
increased light scattering in S3 lm and will harvest more light
during photo conversion. Aer dye loading, diffused reectance
of all photoanode lms were decreased signicantly due to light
absorption by the dye and are shown in Fig. 5d. The dyed S3
photoanode lm is reported to have more absorption with lower
diffused reectance in the 350–700 nm region compared to
other samples.
The amount of dye loading at photoanodes directly have
profound effect on the photocurrent density are summarized in
Table 2, Fig. S4 and Note S4, ESI.† The measured dye loading
behaviour matches with the trend of the UV-vis reectance data.
The specic surface area is directly correlated to different size
particle distribution along the photoanode lms, also the
roughness of the lms have to be considered as a signicant
factor which directly inuence the amount of dye loading. This
provides more number of sites to anchor dye molecules and
Fig. 5 (a) Bargraph shows the composition of S1, S2 and S3. (b) Cross
sectional image of film S1 and inset SEM image show uniformly
oriented nanoparticles with high porosity. (c) and (d) Diffuse reflec-
tance spectra of S1, S2 and S3 photoanodes before and after dye
loading respectively.
Table 2 Different parameters of TiO2 based photoanode filmsa
Sample
wt% of TiO2 prepared at
40
C in sample
Rrms
(mm)
Dye loading amount
(10 9
mol cm 2
)
S1 0 0.069 3.6066
S2 16 0.101 3.9421
S3 40 0.130 4.2392
a
These values refer to the percentage of the TiO2 prepared at 40
C in
sample and lm surface root mean square roughness, Rrms.
Fig. 6 (a) Schematic representation of fabricated DSSC. (b) Current density–voltage curves of the DSSC consisting 40
C, 10
C, P25, S1, S2
and S3 samples as photoanodes under one sun illumination.
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6. shows S3 photoanode's dye loading capacity is higher compared
to other samples (4.2392 10 9
mol cm 2
).
The schematic diagram of DSSC is presented in Fig. 6a and
a photograph of one of the fabricated DSSC is shown in the inset
of same. The current density–voltage curve and parameters of
all DSSCs are reported in Fig. 6b and Table 3 respectively. It has
been observed that pristine P25, TiO2 synthesized at 40
C or
at 10
C were able to achieve 11.4 mA cm 2
of photocurrent
while S1, S2 and S3 combinations show remarkably higher
photocurrent (see ESI Table A1†). The S3 photoanode DSSC
have high anatase percentage with oval shaped nanoparticles
exhibiting high specic surface area with more sites to anchor
more dye which eventually combines yielding enhanced photo-
conversion efficiency and reported high efficiency of 8.6%
compared to the other samples. Improving DSSC performance
depends on the enhancement of the photocurrent Jsc which can
be credited to the well-developed light scattering structure of
the photoanode which increases the light harvesting, as the
open circuit voltage Voc and ll factor (FF) have little difference
among the cells. Reduced photocurrent in S2 and S3 can be
explained by the less dye loading due to higher percentage of
nanorods composition, low roughness and decreased sites to
attach dye. Also, band gap of the TiO2 prepared at 40
C is
wider than 10
C, which exhibits faster electron transport at
the interfaces.51
It appears clearly from the above ndings that
efficiency is a function of percentage of the TiO2 synthesized at
40
C in photoanodes, although particle size and shape also
show their direct impact on the cell efficiency.
EIS has been widely used to analyse various parameters
attributed to electrons transport in the TiO2 interface and
recombination between electron at LUMO level of dye and the
redox electrolyte are listed in the Table 4. Inset of Fig. 7a shows the
equivalent circuit of all fabricated DSSCs. Under illumination,
sheet resistance is observed as almost same for all DSSCs and as
identical Pt counter electrodes were used during the fabrication,
there is no signicant change in the value of R1. In such condition
charge transport resistance R2 decreased in S3 resulting in fast
electron transport at electrolyte–dye–photoanode junction in the
S3 DSSC shown in Fig. 7a. In dark condition EIS shown in Fig. 7b,
Table 3 Different parameters of DSSC with different photoanode filmsa
Sample wt% of anatase Jsc (mA cm 2
) Voc (V) FF h (%)
40
C 58 9.69 0.9 0.68 0.01 50.8 0.9 3.3 0.02
10
C 27 7.86 0.02 0.73 0.01 50.79 0.2 2.9 0.05
P25 80 11.4 0.01 0.71 0.01 64 0.01 5.2 0.08
S1 59 17.44 1.4 0.68 0.01 57.67 0.33 6.9 0.5
S2 64 18.07 0.7 0.7 0.02 65.54 1.54 8.2 0.8
S3 71 18.46 0.4 0.7 0.01 66.46 1.46 8.6 0.3
a
Short circuit current density, Jsc, open circuit voltage, Voc, ll factor, FF and photoconversion efficiency, h are the parameters of DSSC examined at
AM 1.5G 1000 W m 2
by keeping 0.09 cm2
as the working area for all the solar cells.
Table 4 Experimental parameters of DSSC obtained by the equivalent
circuita
DSSC
Under illumination In dark
Rs/U R1/U R2/U Rs/U R1/U R2/U
S1 14.97 17.47 4.817 15.12 30.53 12.53
S2 14.82 19.11 4.63 15.45 26.73 3.757
S3 15.14 15.66 3.124 12.72 35.37 4.575
a
Sheet resistance and series resistance are obtained under illumination
at AM 1.5G 1000 W m 2
and in dark. The derived parameters are
corresponds to high performed cells in Table 3.
Fig. 7 Nyquist plot of DSSC with S1, S2 and S3 samples as photo-
anodes (a) under illumination and (b) in dark respectively.
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7. no electron jumped from LUMO level of dye to TiO2 and it implies
transport of electrons to the electrolyte specimen. So R2 transport
resistance attributes recombination rate at these junction.52,53
The
sheet resistance (Rs) is the combine value of resistance of the FTO
glass, contact resistance of the DSSC and resistance created due to
external circuits. The charge transfer between Pt counter electrode
and electrolyte is demonstrated by rst semicircle (R1). The elec-
tron transfer at electrolyte–dye–photoanode interface serves as
charge transport and recombination represented by the inter-
mediate semicircle (R2). Diffusion of the iodide species in elec-
trolyte is shown by the third semicircle.54
Conclusions
This work states the detailed and complete analysis of TiO2
synthesized by one step sub-zero temperature method with well
crystallized anatase and rutile nanoparticles. The reaction
temperature of synthesis process exhibits variation in phase
composition which implies morphological changes such as size
and shape of nanoparticles. This change is mainly caused by
phase combination, lattice strain, defects present on the grain
boundaries and nucleation-growth rate of particles. These
materials were used as photoanode for DSSC. Remarkably,
enhancement in both photocurrent density and photo-
conversion efficiency, 18.46 mA cm 2
and 8.6% respectively
were reported for the S3 DSSC. Enhancement arises from high
percentage of anatase phase (0.5%), optimized lm thickness
(14.5 mm), increased charge transport along with decrease in
recombination rate at electrolyte–dye–photoanode (3.124/U),
higher Rrms (0.130 mm) with different size and shape nano-
particles harvest more light. The present work provides
a simple, controlled one step process to synthesize TiO2 and its
application in DSSC with high performance open window
towards more applications like batteries, photocatalysis and
biosensors etc.
Acknowledgements
The authors are grateful to Department of Science and Tech-
nology, Govt. of India and Indo-Portuguese program of coop-
eration in science and technology, 2014–2016 (Grant No. SR/FT/
CS-144/2011 and INT/Portugal/P02/2013) in terms of nancial
support. The authors would like to thank Dr Ritu Gupta for
helping out with the correction. We would also like to
acknowledge the Material Research Centre, MNIT Jaipur, India
for providing TEM Characterization facility.
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