Perovskite Solar Cells an
Efficient, Low Cost, Emerging Photovoltaic Technology
Yogesh Kumar Dongre* and Sanjay Tiwari
Studies in Electronics & Photonics, Pt. Ravishankar Shukla University,
Raipur-492010, Chhattisgarh (India)
20 November 2019; Accepted: 22 September 2020]
halides compound shortly named as perovskite represent an emerging active layer
materials for photovoltaic technology. In recent years perovskite shows
capability of developing high performance photovoltaic devices with higher
efficiency at a low cost. This review article discuss the current status of methylammonium
metal halide (perovskite) based photovoltaic devices and provide a
comprehensive review of ABX3 device structures, fabrication methods,synthetization,
film properties, and photovoltaic performance. The flexibility, simplicity and
low cast processing of perovskite solar cell fabrication methods allow using
various types of device architectures. The article also focuses on the journey
of perovskite solar cell. In 2009 first perovskite solar cell was reported and
it shows power conversion efficiency (PCE) of around 3–4%.In 2017 the PCE was
reported around 22.1%, now a day (in 2019) 28% power conversion efficiency is
reported by Oxford PV’s which is tandem solar cell based on perovskite-silicon.
In this article the issue related to efficiency enhancement, stability and
degradation mechanism are presented.
solar cells, methyl
ammonium metal halide, perovskites, stability, crystal structure.
name comes from a Russian mineralogist L. A. Perovski and discovered by Gus-tav
Rose in 1839. In 1978, the material that is responsible for the main part of perovskite solar
cells was introduced as organo metal halide CH3NH3BX3
by Weber. Here, B stands for metal elements and X substitutes for halide
elements (Mitzi, et al. 1994).CH3NH3BX3
has a specific crystal structure with the ABX3 formula (X = oxygen, halogen).
The larger A cation occupies a cubo-octahedral site shared with twelve X anions
while the smaller B cation is stabilized in an octahedral site shared with six
X anions.The perovskite materials raises very earlier from 2006
at this stage it was very new technology and shows efficiency around 2.2%, but
the first incorporation into a solar cell was reported by Miyasaka et al., 2009
(Kojima et al., 2009). This was based on dye-sensitized solar cell architecture, and generated only 3.8% power
conversion efficiency (PCE) with a thin layer of perovskite on mesoporous TiO2
as electron-collector. Moreover, because a liquid corrosive electrolyte was
used, the cell was only stable for a matter of minutes. Park et al., 2011
improved, using the same dye-sensitized concept, achieving 6.5% PCE (Im et al., 2011).There are some another low cost solar PV technology
like Polymer, Dye synthesized, Quantum Dot are also available, The low
efficiency is major issue in 3rd generation Solar cell (Verma et al.,
2017). Because of high efficiency researcher gives keen
interest on the development of perovskite based solar cell.
Mike Lee et al., 2012
reported that the perovskite was stable if contacted with a solid-state hole
transporter such as spiro-OMeTAD and replaced the requirement of mesoporous TiO2
layer in order to transport electrons (Lee et al., 2012, Hadlington, 2012).They showed that efficiencies of almost 10% were
achievable using the 'sensitized' TiO2 architecture with the
solid-state hole transporter, for higher efficiencies, above 10%, were attained
by replacing it with an inert scaffold (Kim
et al., 2012). Furthere xperiments in replacing
the mesoporous TiO2 with Al2O3 resulted in
increased open-circuit voltage and a relative improvement in efficiency of 3–5%
more than those with TiO2 scaffolds (Liu,
et al. 2013).Scaffold architecture shows
hypothesis which is not needed for electron extraction, which was later, proved
correct. The result from scaffold architectures is then closely demonstrated
the result that the perovskite itself could also transport both holes and
electrons (Ball et al., 2013). A thin-film
perovskite solar cell, with no mesoporous scaffold, of more than 10% efficiency
was reported (Eperon et al., 2014, Saliba et al., 2014, Tan et al., 2014). Summarised data of introduction with their efficiency and specified
parameters is listed below in table 1.
Table 1. Reported efficiency of perovskite solar cell
Kojima, A., Teshima, K., Miyasaka, T.
& Shirai, Y.
Organic-inorganic halide perovskite
Miyasaka et al
Based on dye-sensitized solar cell
Park et al.
Same dye-sensitized concept
Henry Snaith and Mike Lee
Solid-state hole transporter such as
spiro-OMeTAD and replaced the requirement of mesoporous TiO2 layer
Burschka et al.
Two-step solution processing
Planar thin-film architecture
Researchers from KRICT and UNIST
Single-junction perovskite solar cell
Researchers from KRICT
Single-junction with different
architecture perovskite solar cell
Single-junction, Tandem solar cell
based on perovskite-silicon
et al., (2013) for increasing the efficiency of cell, a deposition technique
was demonstrated with the sensitized architecture,efficiency exceeding from 15%
by a two-step solution processing, (Burschka et al., 2013).
Olga Malinkiewicz et al. and Liu
et al., 2013 also worked on these and gives a proposed possible
way to fabricate planar solar cells by thermal co-evaporation techniques
and achieved more than 12% and 15% efficiency in a p-i-n and an n-i-p
architecture respectively (Malinkiewicz et al., 2014, Liu et al., 2013).Docampo et al., 2013 showed 10% efficiency of fabricated
perovskite solar cells in the typical 'organic solar cell' architecture, an
'inverted' configuration with the hole transporter below and the electron
collector above the perovskite planar film (Docampo
et al., 2013).
deposition techniques and higher efficiencies were reported. A reverse-scan
efficiency of 19.3% was claimed by Yang Yang  using the planar thin-film
architecture (Zhou et al., 2014). PCE values over 20% are realistically accepted with
the use of cheap organometal halide perovskite materials, because of
efficiencies have quickly raised to 18-22 % in just 2 years. In addition,
comments on the issues to current and future challenges are mentioned.
Perovskite material structure
The perovskite (the
mineral) is composition of calcium, titanium and oxygen in the form CaTiO3.
Meanwhile, a perovskite structure is anything that has the generic form ABX3
and thesame crystallographic structure as perovskite(Giorgi
et al., 2013). The perovskite lattice and
morphology arrangement is discussed below.A large atomic or molecular cation
(positively-charged) of type A are situated in the centre of a cube. And the
corners of the cube are then occupied by atoms B (positively-charged cations)
and the cube faces are occupied by a smaller atom X with negative charge
Figure 1. ABX3 perovskite structure showing BX6
octahedral and larger A cation occupied in cubo-octahedral site and Unit cell
of cubic CH3NH3PbI3 perovskite, (Giorgi, et al.
structure of the perovskites currently used in solar cells consists of a
network of corner-sharing BX6 octahedral with the B cation
(typically Sn2+ or Pb2+) and X is a halogen
grouptypically F-, Cl-, Br- or I-.
The cation A is selected to balance the total charge and it can be an organic
(eg. Methylammonium CH3NH3+, Formamidinium NH2CH=NH2+)
or inorganic material like Cs+ ion (Borriello,
et al. 2008, Kagan, et al. 1999). Perovskites are well known for their phase
complexity, with accessible cubic, tetragonal, orthorhombic, trigonal and
monoclinic polymorphs depending on the tilting and rotation of the BX6
polyhedra in the lattice (Tributsch, H. 2004). Phase transitions are frequently
observed in lead perovskites under the influence of temperature, pressure
and/or applied electric field (Mitzi, et al. 1995).
light absorber: Structure
A and B
are usually divalent and tetravalent, respectively whenever O2- anion
is used.Charge neutrality is done by perovskite halogen anions allow monovalent
and divalent cations in A and B sites, respectively. In CH3NH3PbI3,
the A-site cation is CH3NH3+ and the B-site
cation is Pb2+, as shown in Fig. 1. The formability of perovskite is
estimated based on its geometric tolerance factor (t) t = (rA + rX)/[H2(rB
+ rX)], where rA, rB and rX are the effective ionic radii for A, B and X ions,
respectively(Goldschmidt, V. M.1927). For transition metal cations containing oxide
perovskite, an ideal cubic perovskite is expected when t = 1 while octahedral
distortion is expected when t < 1. Symmetry also decreases for t < 1,
which may affect electronic properties (Rini, et al.
alkali metal halide perovskite, formability is expected for 0.813 < t <
1.107 (Li, et al.2008).
Optical band gap and absorption
coefficient of CH3NH3PbX3
absorption coefficient of ABX3, here CH3NH3PbX3
was estimated from a nanocrystalline TiO2 thin film surface coated
with CH3NH3PbX3. Table 2 shows the absorption
coefficient as a function of wavelength for the CH3NH3PbX3
nanodot-coated TiO2 film.
coefficient (α) as a function of wavelength for perovskite CH3NH3PbX3
nanodot coated with 1.4 µm TiO2 film (amount of adsorbed perovskite =
3.2 ×10^4 /µm2), α was obtained from T = I/I0 = exp (_α l), where T,
I, I0 and l represent transmittance, transmitted light intensity, incident
light intensity and TiO2 film thickness, respectively.
Table 2.Absorption coefficients, as a function ofwavelength.
absorption coefficient was estimated to be 1.5 ×10^4 cm-1 at 550
nm, indicating that the penetration depth for 550 nm light is only 0.66 µm.
At 700 nm, the absorption coefficient was 0.5 ×10^4 cm-1,
corresponding to a penetration depth of 2 µm. Incoming light mostly absorbed
by the perovskite within a thin layer of about 2 µm, which is suitable as a
sensitizer for high efficiency solid-state sensitized solar cells(Kim, et
Physical device structure of perovskite solar cells
As the technology
mature the structure of perovskite solar cell offered variety of structure with
theirown significant. With respect to the time the physical structural designed
and concept are changed. Perovskite material is basically chemical compound so
the structure is also based on chemical reaction of materials. The various
structures with their concept and maturity are listed below.
Table 3.Various Spectrum analysis of CH3NH3PbI3
ultraviolet photoelectron spectroscopy (UPS) and the Tauc plot obtained with
UV–vis spectral data, valance band maximum (VBM), band gap, and conduction
band minimum (CBM) for CH3NH3PbI3 were
estimated to be 5.43 eV, 3.93 eV and 1.5 eV, respectively, as depicted in
Fig. 5. From a thermodynamic view-point, the VBM position is suitable for
hole separation while CBM is suitable for electron separation. On the basis
of band gap energy, the absorption onset wavelength is expected to be around
826 nm(Kim, et
Table 4. Absorption coefficients as a function of wavelength
was first used as in which molecular dye concept was replaced by perovskite a
sensitizer in dye-sensitized solid-state devices. In the sensitization
concept shown in Fig. 6, to induce heterojunction concept HTM should be fully
infiltrated inside the mesoporous oxide layer. In addition, oxide layers with
electron accepting properties are required to separate the photo-excited
electrons in perovskite(Kim, et al. 2012).
Al2O3 served as a scaffold layer because electron
injection from perovskite to Al2O3 was not allowed. So
the result of this architecture the sensitization concept is not always
necessary for perovskite solar cell design. So perovskite solar cells were
confirmed to work in the absence of a mesoporous TiO2 layer. As
shown in Fig. 7, the CH3NH3PbI3_xClx thin
layer coated Al2O3 film had a PCE of 10.9% (Lee, et
pillared structure was designed in which the pores of a mesoporous TiO2
film (pillars) were filled with perovskite instead of a surface coating. As
shown in Fig. 8, a thin capping layer (over active layer) was formed after
infiltration with the perovskite. PCE
of 12% was reported using CH3NH3PbI3 and
polytriarylamine (PTAA) (Heo, et al. 2013).For higher PCE in pillar
structure, the pillared structure with a two-step coating procedure was used.
CH3NH3PbI3 layer was prepared by dipping the
PbI2 layer formed in mesoporous TiO2 film into a
diluted CH3NH3I solution while the perovskite layer was
in contact with spiro-MeOTAD, 15% PCE was achieved in this structure (Burschka,
et al. 2013).
structure with deposited CH3NH3PbI3_xClx
film was designed. In addition to the
sensitization and planar pin junction concepts, a pn junction structure is
available. A pn junction structure with FTO/TiO2/CH3NH3PbI3/Au
configuration was proposed Fig. 9 in which CH3NH3PbI3
was used as a p-type semiconductor (Laban,et
al.2013).5.5% PCE with a
500 nm-thick nanosheet TiO2 film for the n-type layer with
HTM-free perovskite solar cell was showed initially. Then after replacing the
TiO2 nanosheet with a thinner nanoparticle TiO2 film,
PCE was improved to 8%(Green, et al. 2017).
Perovskite solar cells efficiency from beginning to
Plots show the
progress in perovskite solar cell efficiency by year. Since 2009, organolead
halide perovskites have been used for solar cells and 3.8% PCE were reported.
For improvement in efficiency and stability in 2012 liquid dye was replaced by
solid HTM. Since then, solid-state perovskite-containing solar cells have been
called perovskite solar cells.
Progress in perovskite solar cell efficiency by year (Vidyasagar,
et al. 2018).
of June 10th 2014, the certified record PCE of 17.9% was achieved by the Korean
Research Institute of Chemical Technology (KRICT), which was certified by the
National Renewable Energy Laboratory (NREL, 2018). Recently in 2017 the 22.1% PCE
was reported by KRICT co-authorship (Seo, et al. 2016) and 2018 from the Energy
Environmental Science report 23.9% PCE was achieved (Vidyasagar, et al. 2018).
Stability and degradation issue in perovskite solar
years reported result, shown very well understanding about the efficiency
enhancement with different architecture. Perovskite materials offers higher
efficiency with compare to other standing solar technology, because of the
absorption coefficient is higher, higher charge carrier mobility and higher
open circuited voltage. But the major
issue related to the performance of perovskite solar cell are their degradation
and instability in environment and another changing atmosphere. The life time
of cell is very short and it degrades within very short time some of the cells
shown degrade in less than 10 min during the measurement procedure itself. Due
to degradation Perovskite solar cell shows instability. There are various
issues for instability the chemical reaction between perovskite with other
materials shows rapid crystallization between organic cations and PbI2”
is stressed as is the role of manipulating “the chemical composition of the
perovskites via solvent engineering and intra molecular exchange process” ((Vidyasagar
et al., 2018). The
luminescent properties of the perovskite materials need to be better understood
to improve open-circuit voltage (Voc). To overcome degradation issues, replace
metal electrodes with something like indium−tin oxide because the halogens in
the perovskite react with most metals.
stability results, however, have recently been reported for solid solutions of
Cs and FA lead-halide perovskites (Berhe et al.,
Another way to increase the stability of perovskite at high relative humidity
is to form the mixed halide perovskite. The simple solution mixture of CH3NH3PbI3
and CH3NH3PbBr3 was reported to result in a
solid-solution of CH3NH3PbI3_xBrx (x = 0–3) (McGehee M,
triio-dide and tribromide perovskite have a band gap difference, the solid
solution resulted in band gap tuning and colour control. The inclusion of
bromide in CH3NH3PbI3 will likely enhance the
stability of the CH3NH3+ cation in the lattice.
Hysteresis effects in
perovskite solar cell
current-voltage response curves fluctuations are depending on the presence of
Hysteresis, so the corresponding photovoltaic parameters vary depending on the
rate of the scan and scanning direction. Reliable photovoltaic operation and stability
of organic-inorganic perovskite solar cells affected by the influence of
hysteresis effects. Ferroelectric polarization, ion migration, charge trapping,
and capacitive effects, are the major responsible mechanisms behind the origin
of hysteresis phenomenon in perovskite solar cells(Noh et al.,
of hysteresis in ferromagnetic materials is the result of two effects, rotation
of magnetization and changes in size or number of magnetic domains. In general,
the magnetization varies (in direction but not magnitude) across a magnet. For
high efficient solar cell we require very low hysteresis loss (Elumalai et
Because of metal
materials Hysteresis Effects originated in perovskite solar cell. For
observation of capacitive effects in perovskite-absorber devices of different
architecture and study changes in devices during degradation, Staircase
voltammetry is used. Hysteretic phenomena have been observed in solar cells
other than perovskite-absorber solar cells (Jacobs et
most of cell was designed with organolead halides, lead is toxic material and
it react with environment and gives harmful effect to human being so researcher
took around the other material (Sn, K) in place of lead. With these materials,
a PCE of 20% is expected from single junction structures and a PCE of 29% is
expected from tandem structures (Unger, et al. 2014, Park, N. G. 2013).Higher
efficiency is still possible through structural modification (Park N. G.,
2013), along with band gap tuning.
Modification of the bond distance and/or angle of X–Pb–X in CH3NH3PbX3
is one of strategies to tune band gap energy. More recently, a PCE approaching
30% was achieved from a single junction perovskite solar cell (Snaith H. J.,
Pb-free compounds such as MA2AgBiI6, with a
double-perovskite unit cell, also have excessively high band gap (Yin et al., 2014,
Volonakis et al., 2016).The
same approaches will be done using Sn based perovskite material. Preciously
control of the luminescent property of perovskite could further improve Voc,
hence contributing to an even higher PCE.
Clean and green electricity
is most requiring thing for human being. The sun is the source of light energy,
and we are converting this light into electricity by using device called solar
cell. Today varieties of solar cell are present with various specific
parameters. Now solar industries are based on Silicon (Si) technology, we know
its mature technology but the cost and processing of Si solar cell is very high.
Now a day a new kind of solar cell were reported and on progresses named
perovskite solar cell. This review article, represent perovskite solar cells in
the order of historical background, materials used, production of perovskite
solar cells and their properties and mechanisms to explain them properly. Within
a journey in term of efficiency, its dominant some other solar cell technology
like Dye solar cell, Organic solar cell, etc. The instability and degradation
and toxicity in case of Pb based perovskite are major issue in perovskite solar
cell. More broadly, the progress work will create a transformative, high
efficient, low cost, and easy to fabrication to serve as bridge between basic
Photovoltaic sciences, applied sciences and engineering and photovoltaic
technology. In future so its stand with Silicon based technology.
I would like
to express my sincere gratitude to my supervisor Prof. Sanjay Tiwari for the
continuous support of my research, for his motivation, and immense knowledge. I
am also thankful to Photonics Research Laboratory, Pt. Ravishankar Shukla
University, Raipur, Chhattisgarh (India) for research facilities, and Group
members are also thankful and acknowledged.
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