Received: 25 September 2023 | Revised: 19 January 2024 | Accepted: 15 February 2024
DOI: 10.1002/ese3.1724
OR IG INAL ART I C L E
The influence of methylammonium iodide concentration
on the properties of perovskite solar cells
Naveen Kumar Elangovan1 | Raju Kannadasan1 | Max F. Savio2 |
S. Vinson Joshua3 | Muhammad Faheem4
1Department of Electrical and Electronics
Engineering, Sri Venkateswara College of
Engineering, Chennai, India
2Department of Electrical and Electronics
Engineering, Saveetha Engineering
College, Chennai, Tamil Nadu, India
3Department of Electronics and
Communication Engineering, Vel Tech
Rangarajan Dr. Sagunthala R & D
Institute of Science and Technology,
Chennai, India
4Department of Computing Science,
School of Technology and Innovations,
University of Vaasa, Vaasa, Finland
Correspondence
Muhammad Faheem, Department of
Computing Science, School of Technology
and Innovations, University of Vaasa,
Vaasa 65200, Finland.
Email: muhammad.faheem@uwasa.fi
Abstract
This study focuses on improving the quality of MAPbI3‐based perovskite films
by adjusting the concentration ratios of the methylammonium iodide (MAI)
precursor using a two‐step sequential deposition method. The primary
objective is to explore how altering the MAI concentration influences the
microstrain, dislocation density, perovskite film quality, and their subsequent
impact on the performance of perovskite solar cells. The examined device
configuration CdS/MAPbI3/Spiro‐OMeTAD demonstrates impressive power
conversion efficiency of 12.05%, Voc of 1.02 V, Jsc of 16.2 mA cm
−2, and fill
factor of 0.73. X‐ray diffraction and scanning electron microscope analyses
show improved crystal quality and surface characteristics with reduced
microstrain, dislocation density, larger crystal grains, and minimized pinholes.
The investigation of MAPbI3's optical and electrical characteristics provides in‐
depth insights, facilitating the optimization of MAI precursor concentrations
for improved perovskite film development and enhanced solar cell
performance.
KEYWORD S
dislocation density, MAPbI3, microstrain, perovskite deposition, perovskite solar cell, series
resistance
1 | INTRODUCTION
Organic–inorganic halide perovskite solar cells have
garnered substantial attention due to their remarkable
increase in power conversion efficiency (PCE), soaring
from 3.81% to an impressive 25.7%.1 This significant
progress has positioned them as one of the most
promising photovoltaic (PV) technologies. Their excep-
tional optical and electrical properties contribute to their
appeal, boasting a large absorption coefficient of
105 cm−1, high charge carrier mobility, and a long
diffusion length ranging from 100 to 1000 nm. Addition-
ally, these perovskite solar cells exhibit a low exciton
binding energy, tunable band gap, bipolar transport
Energy Sci. Eng. 2024;12:2004–2016.2004 | wileyonlinelibrary.com/journal/ese3
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© 2024 The Authors. Energy Science & Engineering published by Society of Chemical Industry and John Wiley & Sons Ltd.
Abbreviations: AFM, atomic force microscopy; ETL, electron transport layer; FF, fill factor; HTL, hole transport layer; JSC, short circuit current;
PCE, power conversion efficiency; PSC, perovskite solar cells; PV, photovoltaic; Rs, series resistance; Rsh, shunt resistance; SEM, scanning electron
microscope; VOC, open circuit voltage; XRD, X‐ray diffraction.
nature, and simplified manufacturing process.2 Re-
searchers have extensively explored the utilization of
diverse perovskite materials—including MAPbI3,
MAPbBr3, MASnI3, CsPbBr3, and FAPbI3—as active
layers in perovskite solar cells (PSCs).3,4 Indeed, the
quality of the perovskite material holds a substantial
influence on the device's performance. Superior perov-
skite materials are crucial for maximizing light absorp-
tion, reducing charge recombination, and extending
carrier diffusion length, all of which improve solar cell
efficiency.
Undoubtedly, enhancing the quality of perovskite
material stands as a key approach to boosting the
performance of perovskite solar cells (PSCs). Crucial to
achieving high film quality with improved crystallinity,
larger grains, and smooth surfaces is the meticulous
control of perovskite growth on diverse substrates.5–7
Solution‐processing techniques are predominantly used
in preparing perovskite solar cells, making the composi-
tion of the precursor solution equally critical. Several
solution‐processing deposition methods are employed in
perovskite fabrication one‐step, two‐step, sequential
vapor deposition, two sources vapor deposition, and
vapor‐assisted solution deposition. Among various depo-
sition techniques, two‐step deposition method is pre-
ferred in perovskite fabrication due to several advantages
over other deposition techniques: cost‐effective, con-
trolled nucleation, reduced defects, improved crystallin-
ity, tunable properties, and enhanced stability. The
electronic structure of MAPbI3 exhibits high stoichio-
metric and surface defect tolerance factors during
fabrication, rendering it insensitive to a wide range of
compositional changes. However, the ideal quantity of
methylammonium iodide (MAI) or PbI2 precursor
solution for optimal perovskite material performance
remains uncertain. Additionally, researchers have pro-
posed various mechanisms responsible for the notable
enhancements observed.8–11 It is imperative to further
explore these mechanisms to gain deeper insights into
the improvement of perovskite materials and, conse-
quently, PSC efficiency.
The precursor solution's concentration ratio plays a
vital role in governing the crystallinity, morphology, and
colloidal properties of perovskite materials. The existing
colloidal particles act as nucleation sites during the
formation of perovskite films from the precursors, thereby
influencing the overall film quality.12 Hong et al. con-
ducted a study where they carefully adjusted the MAI and
PbI2 ratios under Pb‐rich/I‐rich conditions to create
MAPbI3 films. They found that solvent engineering and
stoichiometric ratios had a significant impact on the
efficiency, photostability, surface morphology, and cover-
age of MAPbI3 films.
13 In another approach, the addition
of excess MAI to the precursor solution, combined with
deposition using a Lewis acid–base adduct, effectively
suppressed recombination at grain boundaries, leading to
improved performance.14 Chen et al. demonstrated that
releasing organic species during the annealing process
allowed the presence of the PbI2 phase in the grain
boundaries of perovskite, resulting in enhanced carrier
behavior and stability.15 Huang et al. found that using
DMF as a solvent for MAI and PbI2 was advantageous, as it
controlled the crystallization rate, facilitating the formation
of compact perovskite films.16 Wieghold et al. affirmed that
higher precursor concentrations contributed to the forma-
tion of larger and more oriented grains in MAPbI3 films.
17
Byung‐Wook Park et al. showcased how the presence of
excess lead iodide in the perovskite precursor solution
played a crucial role in achieving PCEs exceeding 20% by
reducing halide vacancies.18 Also, A mechanism elucidat-
ing the generation of distinct morphologies was postulated
through the integration of in situ crystal growth analysis
with X‐ray diffraction (XRD) measurements. The thin film
crystals produced at both low (60°C) and high (120°C)
temperatures exhibit (110) and (200) orientations, respec-
tively. This discrepant manner of crystal growth engenders
substantially dissimilar film morphologies. In comparison
to the spin‐coating method, drop‐casting demonstrates
significantly heightened resilience against humidity‐
induced effects. Notably, PV cells based on MAPbI3
fabricated under 88% humidity conditions yielded an
impressive PCE of 18.17%. This achievement stands as
the pinnacle PCE for perovskite solar cells manufactured
in environments exceeding 70% humidity, all achieved
without the utilization of antisolvent agents.19
Furthermore, many findings have been reported on
the approach of various precursor concentrations using a
two‐step sequential deposition technique in which PbI2 is
coated first and MAI is spin‐coated later. However, most
previous studies focused on improving perovskite film
quality by focusing on the process of film formation via
deposition methods and tuning the concentration
ratios.20–23 Nevertheless, no detailed studies on the effect
of microstrain and dislocation density on the MAPbI3
perovskite film quality have been reported.
This article focuses on enhancing the quality of
MAPbI3‐based perovskite by varying the MAI precursor
concentration ratios through a sequential deposition
process using the spin coating method. The investigation
delves into the impact of different MAI precursor
concentration ratios on the film quality of the perovskite,
specifically examining microstrain and dislocation den-
sity. Extensive analysis of the MAPbI3‐based perovskite
material and the influence of lead iodide (PbI2)
concentration on its properties is conducted. XRD
measurements demonstrate that the perovskite film
ELANGOVAN ET AL. | 2005
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quality experiences improvement, attaining the lowest
microstrain and dislocation density with an optimal MAI
(35mg) PbI2 (464mg) precursor solution ratio. Scanning
electron microscopy (SEM) reveals that the perovskite
film with an optimal MAI (35mg) ratio exhibits a larger
grain size, reduced pinholes, and uniform surface
coverage. The corresponding perovskite solar cell, with
a device structure of FTO/CdS/MAI (35mg) PbI2/Sprio‐
OMeTAD/Ag, achieves an impressive PCE of 12.05%.
Additionally, the study delves into the intricate propert-
ies of the perovskite material, providing valuable insights
for potential future development paths. By elucidating
the optimal MAI precursor concentration ratio and its
influence on film quality and solar cell performance, this
research paves the way for further advancements in the
field of perovskite‐based solar cells. Here is a summary of
the contribution's points for this article:
• Enhance the quality of MAPbI3‐based perovskite by
varying the concentration ratios of the MAI precursor
using a sequential deposition technique with spin coating.
• The impact of different MAI precursor concentration
ratios on film quality is investigated, focusing on
microstrain and dislocation density in the perovskite
material.
• XRD measurements reveal that an optimal MAI
(35mg) PbI2 (464 mg) precursor solution ratio results
in improved perovskite film quality with the lowest
microstrain and dislocation density.
• The study also demonstrates that the perovskite film
with the optimal MAI (35mg) ratio exhibits larger grain
size, reduced pinholes, and uniform surface coverage,
leading to a perovskite solar cell with an impressive PCE
of 12.05%.
The remaining sections of the article are organized as
follows: Section 2 discusses the experimental method.
Section 3 presents the fabrication and characterization.
Section 4 presents the simulated results obtained from
implementing the proposed methodology. Finally,
Section 5 concludes the work based on the attained
outcomes from the entire study.
2 | EXPERIMENTAL METHOD
2.1 | Materials
The following materials were used to prepare the
material layers: MAI, methylammonium lead iodide
(MAPbI3), isopropyl alcohol (IPA), lead iodide (PbI2),
dimethyl sulfoxide (DMSO), N,N‐dimethylformamide
(DMF), fluorine‐doped tin oxide (FTO), cadmium
chloride (CdCl2), liquid ammonia (NH3), thiourea (CS
(NH2)2), chlorobenzene, ethanol and 2,2′,7,7′‐tetrakis‐
(N, N‐di‐4‐methoxyphenylamino)‐9,9′‐spirobifluorene
(Spiro‐OMeTAD). Sigma‐Aldrich and Sri Hari Company
India supplied all of the materials used in this
fabrication.
2.2 | Device structure
The proposed MAPbI3‐based perovskite solar cell has the
following stack of layers: (1) FTO/CdS/MAI(15mg)PbI2(464
mg)/Sprio‐OMeTAD/Ag, (2) FTO/CdS/MAI(25mg)PbI2(464
mg)/Sprio‐OMeTAD/Ag, (3) FTO/CdS/MAI(35mg)PbI2(464
mg)/Sprio‐OMeTAD/Ag. The effective shading mask area
of 0.09 cm2 with a well‐defined aperture is fabricated using
a laser cutting machine, according to the key device
structure. The device's active area was 1 cm2. Figure 1
illustrates the device structure and energy level diagram of
PSC. The overall thickness of the perovskite solar cell for
Sample 1, Sample 2, and Sample 3 is measured to be
around 390 nm± 5 nm, 490 nm± 5 nm, and 540 nm± 5
nm, respectively, using atomic force microscopy (AFM)
analysis. These thicknesses for each layer were calculated
using AFM analysis and each layer is coated separately on
an FTO glass with the same deposition time and RPM as
mentioned for the overall device fabrication. Notably, the
series resistance of the film is taken into consideration for
analyzing the performance of the solar cells.
3 | FABRICATION AND
CHARACTERIZATION
3.1 | Device fabrication
The unwanted FTO glass substrate was removed with
HCl and zinc powder based on the device structure. The
FTO glass substrate was cleaned for 15min each with
acetone, isopropyl alcohol, and deionized water using
ultrasonication. Chemical bath deposition is used to
fabricate the CdS layer on the FTO glass substrate.
100mL 0.25M CdCl2 was taken in a beaker and steered
until 75°C. After reaching the desired temperature,
50mL liquid NH3 was added to the solution and steered
for 25min. The solution slowly changes from colorless to
yellow after adding 2.286 g thiourea. All samples were
removed from the CdS chemical bath after 10 min based
on a previously reported study and rinsed in deionized
water.20 The MAPbI3 layer above the ETL was fabricated
using a sequential deposition method.
To prepare the PbI2 precursor solution, 464mg PbI2 was
added to 1mL of (7:3) (DMF+DMSO) solution and stirred
2006 | ELANGOVAN ET AL.
 20500505, 2024, 5, Downloaded from https://scijournals.onlinelibrary.wiley.com/doi/10.1002/ese3.1724 by Duodecim Medical Publications Ltd, Wiley Online Library on [25/06/2025]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License
for 2 h at 70°C. The precursor solution is then spin‐coated
for 30 s at 4000 rpm on the ETL before being annealed for
10min at 100°C. Furthermore, various precursor solutions
are prepared by adding 15, 25, and 35mg of MAI to 1mL of
IPA solution and stirring continuously until the MAI is
dissolved. The MAI precursor solutions are then spin‐
coated at 4000 rpm for 30 s above the PbI2 layer of Samples
1, 2, and 3, and annealed at 70°C for 10min. The mole
percentage ratio of MAI and PbI2 for Sample 1 is 8.6% and
91.4%; Sample 2 is 13.5% and 86.5%; Sample 3 is 18.1% and
81.9%, respectively. Then, 1mL of chlorobenzene was
added to 40mg of Spiro‐OMeTAD precursor solution and it
is stirred continuously till the solution gets dissolved. After
preparing the solution, a Spiro‐OMeTAD was spin‐coated
over the MAPbI3 layer for 20 s at 4000 rpm. To make an
electrical contact above the hole transport material, Ag was
sputtered. Table 1 summarizes the sequential deposition of
perovskite film with various MAI precursor solution ratios.
Figure 2 illustrates the two‐step fabrication process of
perovskite thin film.
3.2 | Characterization
The surface morphology of the MAPbI3 layers of Samples
1, 2, and 3 was examined using a scanning electron
microscope (Inspect F50‐FEI). The absorption spectrum
of MAPbI3 samples was examined via UV‐visible
spectroscopy (Perkin Elmer spectrometer). The sample
structure and phase identification were investigated via
XRD (XPert PRO—PAN analytical), the thickness of the
sample was analyzed using AFM (XE 70 Atomic Force
Microscopy—Park systems), and I‐V measurements were
performed in the presence of AM 1.5 conditions provided
by the solar simulator (Keithley Electrometer).
4 | RESULTS AND DISCUSSIONS
The optical properties of a CH3NH3PbI3 film made at
different MAI precursor solution ratios of Samples 1, 2,
and 3 were investigated using a UV‐visible spectrometer,
as shown in Figure 3. According to the findings, the
absorption of perovskite films increases with increasing
MAI precursor ratio over the long wavelength range. The
study demonstrates that the CH3NH3PbI3 layer possessed
favorable light absorption characteristics ranging around
400–700 nm for perovskite film fabricated at Sample 3.
The absorption spectrum of perovskite Sample 1 and
Sample 2, on the other hand, is slightly reduced. The
optical bandgap energy was determined to be 1.65, 1.69,
and 1.72 eV (=1241/λonset) for Samples 1, 2, and 3,
respectively, which is greater than the literature reported
value of 1.55 eV. However, depending on the halide
FIGURE 1 Structure and energy level diagram of perovskite solar cell (A–C).
ELANGOVAN ET AL. | 2007
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2008 | ELANGOVAN ET AL.
 20500505, 2024, 5, Downloaded from https://scijournals.onlinelibrary.wiley.com/doi/10.1002/ese3.1724 by Duodecim Medical Publications Ltd, Wiley Online Library on [25/06/2025]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License
content and crystallite size, this energy gap is within the
1.5–2.3 eV range for halide perovskite nanomaterials.
The XRD peaks of perovskite film Samples 1, 2, and
3 are depicted in Figure 4. During the investigation of
the XRD spectra of CH3NH3PbI3, major diffraction
peaks were observed for Samples 1 and 2 at 2θ 12.7°,
14.22°, 19.97°, 28.6°, 32.0°, 36.5°, and 43.2° which
corresponds to (001), (110), (112), (220), (222), (241),
and (314) peaks. However, PbI2 peaks were observed at
2θ 12.7° which corresponds to (001) in the XRD spectra
and 6.972 d‐spacing, indicating that PbI2 has not been
completely converted to perovskite. When compared to
Sample 1, the Sample 2 film has a lower intensity of the
PbI2 peak. Furthermore, the presence of PbI2 causes
faster degradation of the MAPbI3 film. Perovskite film
fabricated with Sample 3 MAI precursor solution, on
the other hand, appear to have major diffraction peaks
at 2θ 14.22°, 19.97°, 28.6°, 32.0°, 36.5°, and 43.2° which
correspond to (110), (112), (220), (222), (241), and
(314) peaks of a tetragonal crystal structure. According
to the data, no PbI2 peaks were detected in the XRD
spectra of Sample 3, indicating that PbI2 has been
completely converted to perovskite. On the other hand,
perovskite inevitably has internal defects, such as Pb
and I vacancy defects, particularly near the grain
boundaries, which diminishes the stability and per-
formance of PSC. When MAPbI3‐based perovskite is
subjected to humid circumstances, the hydrolysis
reaction weakens hydrogen bonds in the crystal
lattices, degrading PbI2 and changing its color from
dark brown to yellow. The dominant factors causing
instability are H2O, O2, ultraviolet light, and heat.
However, the presence of excess PbI2 during the
fabrication of the solar cell can introduce defects or
grain boundaries in the perovskite film, which can act
as sites for charge recombination or promote degrada-
tion under certain conditions. Also, PbI2 may contrib-
ute to the migration of ions within the perovskite layer,
altering the stability of the material and leading to the
degradation of the film over time.
PSCs face crucial challenges regarding stability,
especially the phase instability arising from the Perov-
skite crystal structure and device configuration. Perov-
skites when used in PSC devices are subject to external
factors like environmental stability, thermal stability, and
photo‐stability, all of which have an impact on long‐term
stability. The most important factor contributing to
environmental stability issues in PSCs is encapsulation.
Encapsulation is an effective method for extending the
life of solar cells, reducing photo instability, and
controlling degradation issues by acting as an oxygen
and moisture barrier. Heating Perovskite beyond 100°C
leads to degraded performance due to increased PbI2 and
organic salt formation.
The crystallite size is calculated using Debye‐
Scherrer's law,
FIGURE 2 Schematic illustration of the two‐step fabrication process of perovskite film.
ELANGOVAN ET AL. | 2009
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D λβ θ=
0.9
cos
, (1)
where D is the mean crystallite size, λ is the wavelength
of Cu, β is the full‐width half maximum (FWHM), and θ
is the scattering angle. The average crystallite size of
Samples 1, 2, and 3 were estimated to be 23.88, 24.54, and
32.5 nm. However, smaller crystalline sizes can introduce
quantum confinement effects leading to changes in the
bandgap and affecting the absorbed wavelengths (see
Figure 3). Similarly, altering the halide content modifies
the bandgap, enabling control over the absorption
spectrum of the perovskite film for tailored opto-
electronic performance.
Furthermore, the microstrain (ε) and dislocation
density (δ) were calculated from the XRD data using
the following formulas,
ε β θ= 4 tan , (2)
δ n
D
= ,2 (3)
where n is a factor that is nearly equal to the minimum
dislocation density. The calculated values of the
microstrain and dislocation density of CH3NH3PbI3
are summarized in Table 2. Figure 5 depicts the
microstrain and dislocation density of a CH3NH3PbI3
thin film fabricated at various MAI precursor solution
ratios.
The presence of the maximum microstrain is
observed in the (110), (112), and (220) peaks when
compared to all other peaks of perovskite. The presence
of strain, according to the studies, is capable of inducing
phase transitions in a crystal structure and can com-
pletely shift a material's phase diagram. Smaller micro-
strain, on the other hand, is usually associated with a
more stable crystal. In this case, the perovskite film
fabricated at 35 mg of MAI/IPA solution (Sample 3) has
very low microstrain when compared to the other
samples.
When related to other peaks, the dislocation density
of the perovskite film is greatest for (241) and (314)
peaks. The presence of dislocation density indicates that
the crystal is imperfect. Furthermore, decreasing the
dislocation density will increase in electron lifetime.
According to the results, the film fabricated using the
two‐step deposition method for Sample 3 has the lowest
microstrain and dislocation density. However, both the
microstrain and dislocation density for the fabricated
Sample 3 of perovskite film is minimal when compared
to the reported literature.24 According to the findings, the
presence of maximum microstrain and dislocation
density in the perovskite film may have a significant
impact on the overall PV performance of the PSC while
fabricating a device.25,26
Scanning electron microscopy is a powerful charac-
terization technique that is used to investigate surface
roughness, surface morphology, crystalline packing
density, and other surface‐oriented defects. Figure 6
FIGURE 3 (A) Absorption spectrum and (B) Tauc coordinates
of CH3NH3PbI3 material.
FIGURE 4 Sample 1, 2, and 3 XRD image of CH3NH3PbI3.
2010 | ELANGOVAN ET AL.
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shows an SEM image of a fabricated CH3NH3PbI3 thin
film. According to the results, Sample 3 film fabricated
using the sequential deposition method has fewer
observable pinholes, good crystalline quality, a large
TABLE 2 X‐ray diffraction parameters of Samples 1, 2, and 3
of MAPbI3 fabricated film using a two‐step deposition method.
Samples 2θ
Sized
(nm)
d‐spacing
(Å) hkl Ɛ× 10−3
δ× 10−3
(nm)
Sample 1 14.22 33.74 6.22 110 8.29 0.87
19.97 24.66 4.44 112 8.10 1.64
28.6 20.39 3.11 220 6.88 2.40
32 19.43 2.79 222 6.47 2.64
36.5 21.25 2.45 241 5.20 2.21
43.20 23.85 2.09 314 3.94 1.75
Sample 2 14.22 37.31 6.22 110 7.50 0.71
19.97 26.02 4.44 112 7.68 1.47
28.6 21.69 3.11 220 6.46 2.12
32 20.73 2.79 222 6.06 2.32
36.5 22.5 2.45 241 4.92 1.97
43.20 18.98 2.09 314 4.95 2.77
Sample 3 14.22 39.02 6.22 110 7.51 0.71
19.97 35.07 4.44 112 5.69 0.81
28.6 48.8 3.11 220 2.86 0.41
32.0 25.04 2.79 222 5.02 1.59
36.5 20.4 2.45 241 5.42 2.40
43.2 26.7 2.09 314 3.52 1.40
FIGURE 5 Calculated microstrain and dislocation density of
CH3NH3PbI3 film fabricated at different MAI precursor ratios of
Samples 1, 2, and 3.
grain size, and uniform surface coverage, which has the
potential to reduce leakage current and suppress the
recombination effect when applied to solar cell applica-
tions. However, the presence of pin‐holes in Samples 1
and 2 may allow direct contact of the charge transport
layers through the perovskite layer, resulting in a larger
hysteresis effect and lower PCE. Surface homogeneity is
important in the making of a good‐quality solar cell
device. The final solar cell device performance will be
very poor when the surface has a large number of
pinholes, disorders, and uneven grain formation. The
strong and efficient perovskite solar cell device architec-
ture is based mainly on the surface quality of the
perovskite film. Whereas, the presence of surface
porosity will lead to an immediate recombination effect
and the photo‐generated carrier will recombine near the
defect area. Hence the device's final output will be very
poor and in some cases, the device will not work. In
addition, Samples 1, 2, and 3 films are subjected to AFM
analysis to determine the sample's thickness. As shown
in Figure 7, the film fabricated using the two‐step
deposition method for Samples 1, 2, and 3 has a thickness
of 200 nm± 50 nm, 300 nm± 50 nm, and 350 nm± 50
nm. According to previous studies, increasing the
thickness of the active layer from 100 to 1000 nm shows
an increase in the photogeneration of the electron–hole
pair. However, as the thickness increases beyond the
diffusion length, the PCE decreases.27–29
The effect of various MAI precursor concentration
ratios prepared using the sequential deposition method
on the performance of the Perovskite solar cell was
investigated.
To analyze the PV performance of a perovskite solar
cell, four key solar cell parameters, namely PCE, FF, Voc,
and Jsc, are summarized in Table 3. The FF and PCE of
perovskite solar cells were used to evaluate their overall
performance.
FF V I
Voc Jsc
= max × max
×
, (4)
η Voc Jsc FF
Pin
= × × , (5)
where Vmax represents the maximum photovoltage, Imax
represents the maximum photocurrent, Pin represents the
incident light, and Jsc, and Voc represents the short‐circuit
current and open‐circuit voltage. In this process, the
device architecture of the PSC with device structure CdS/
MAI(35mg)PbI2/Sprio‐OMeTAD/Ag showed a very good
PCE of 12.05%. According to the findings, perovskite
material quality was the first major significant parameter
used in determining the performance of PSCs. The series
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resistance of a perovskite film fabricated for Sample 3
precursor solution ratio is Rs = 6.28Ω.cm
2. Films made
with Sample 1 and 2 precursor solutions, on the other
hand, have series resistances of Rs = 7.61 and 7.15Ω.cm
2,
respectively. Increases in the MAI precursor solution
ratios had a significant impact on increasing PCE.
According to the findings, increasing the MAI precursor
solution ratios results in increased film thickness,
improved film quality, and decreased microstrain, disloca-
tion density, and series resistance. As a result, a thicker
perovskite layer promotes the generation of electron–hole
pairs.30–33 Perovskite has a diffusion length ranging from
100 to 1000 nm, so increasing the thickness of the
perovskite layer in relation to the diffusion length and
overall device architecture results in improved generation
of charge carriers.
FIGURE 6 SEM top surface morphology of the fabricated two‐step perovskite (A) 1 μm ×10,000 and (B) 1 μm ×20,000 of Sample 1, (C)
1 μm ×10,000 and (D) 1 μm ×20,000 of Sample 2, (E) 1 μm ×10,000 and (F) 1 μm ×20,000 of Sample 3.
2012 | ELANGOVAN ET AL.
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FIGURE 7 AFM image of MAPbI3 thin film (A) Sample 1, (B) Sample 2, and (C) Sample 3.
ELANGOVAN ET AL. | 2013
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Based on the observations from Figure 8, it is found
that the initial behavior of the solar cell shows
inhomogeneous characteristics for the various MAI
precursor solution ratios of PSCs; it is due to the effect
of series resistance. Also, the transportation of charges
from the perovskite to the electron and hole transport
layers is hampered by poor film quality, resulting in
increased series resistance by causing a recombination
effect in the device that upholds the inhomogeneous.
This recombination effect declined the generation of
photocurrent and efficiency of the perovskite solar cell.
However, increasing the MAI precursor solution ratios
results in better perovskite film quality for increasing the
voltage for all the considered samples. On the other
hand, a decrease in PCE could be caused by interfacial
resistance at ETL/Perovskite or Perovskite/HTL inter-
faces. Moreover, the use of a nano‐rod or nano‐wire
arrangement for the electron transport layer could result
in a further decrease in interfacial resistance. As a result,
the study shows that increasing the MAI precursor
solution ratios causes a gradual increase in perovskite
solar cell performance. In contrast to voltage, the short
circuit current density of the PSC changes dramatically
with the various precursor solution ratios. Relating the
existing work notably reported by Jeong‐Hyeok Im
et al.,34 the proposed work extensively focuses on the
effect of MAPbI3 microstrain, dislocation density, device
thickness, and series resistance that impact the overall
performance of perovskite solar cells which were not
considered by the existing work.
5 | CONCLUSIONS
According to the findings, the perovskite film fabricated
using the optimal MAI precursor solution ratio of Sample
3 has no PbI2 peaks and has the least amount of
microstrain and dislocation density. SEM analysis, on the
other hand, shows that the film fabricated using Sample
3 precursor solution ratio has fewer observable pinholes,
which reduces leakage current and suppresses the
recombination effect in the perovskite solar cell. The
UV‐visible, XRD, SEM, and AFM data from Samples 1, 2,
and 3 indicate that the Sample 3 precursor solution ratio
is the best for preparing MAPbI3‐based perovskite films
using a two‐step spin coating deposition method. The
highest PCE of 12.05%, Voc of 1.02 V, Jsc 16.2 mA cm
−2,
and FF of 0.728 were obtained for an optimum MAI
precursor solution ratio of Sample 3 for the following
device structure CdS/MAI(35mg)PbI2(464mg)/Spiro‐
OMeTAD. These findings suggest that increasing micro-
strain, dislocation density, and series resistance will have
a significant impact on the performance of a PSC.
Furthermore, the findings of this study will provide a
quantitative understanding of the working mechanism of
a PSC, allowing for further performance enhancement.
ACKNOWLEDGMENTS
The authors express their gratitude to their affiliated
institutes for the financial support provided to conduct
this study.
CONFLICT OF INTEREST STATEMENT
The authors declare no conflict of interest.
TABLE 3 PV parameters for the PSC with various MAI precursor solution ratios.
Device structure with overall
device thickness Jsc (mA/cm
2) Voc (V) FF PCE (%) Rsh (Ω) Rs (Ω)
FTO/CdS/MAI(15 mg)PbI2/Sprio‐
OMeTAD (390 nm± 5 nm)
13.4 1.01 0.715 9.73 1737 7.61
FTO/CdS/MAI(25 mg)PbI2/Sprio‐
OMeTAD (490 nm± 5 nm)
14.5 1.01 0.719 10.60 1852 7.15
FTO/CdS/MAI(35 mg)PbI2/Sprio‐
OMeTAD (540 nm± 5 nm)
16.2 1.02 0.728 12.05 3475 6.28
FIGURE 8 J–V curve of MAPbI3‐based PSC on various
precursor solution ratios.
2014 | ELANGOVAN ET AL.
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ORCID
Raju Kannadasan http://orcid.org/0000-0001-
7622-8261
Muhammad Faheem http://orcid.org/0000-0003-
4628-4486
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How to cite this article: Elangovan NK,
Kannadasan R, Savio MF, Vinson Joshua S,
Faheem M. The influence of methylammonium
iodide concentration on the properties of
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