Direct deposition of Sn-doped CsPbBr3perovskite for efficient solar cell application

Article abstract of DOI:10.1039/d0ra09202a

All inorganic carbon-based planar perovskites, particularly CsPbBr3, have attracted considerable attention due to their excellent stability against oxygen, moisture, and heat for photovoltaic utilization. However, the power conversion efficiency of carbon-based planar CsPbBr3 perovskite solar cells is mostly low, primarily because of the inferior film quality with undesirable crystallization and narrow light absorbance ranges. Herein, we develop a novel direct deposition approach combined with Sn doping to achieve highly efficient and stable carbon-based Sn-doped CsPbBr3 perovskite solar cells. Mass-scale Sn ion-doped CsPbBr3 perovskite powder was effectively synthesized and characterized via a facile strategy by adding hydrohalic acid in the CsBr, PbBr2 and SnBr2 precursor in a dimethyl sulfoxide solution. Moreover, using the as-synthesized CsPbBr3 and Sn-doped CsPbBr3 perovskite powder, PSCs were obtained via effective direct thermal evaporation. A smooth, constant and pinhole-free perovskite film was achieved with a configuration of FTO/TiO2/Sn:CsPbBr3/carbon. PSCs based on Sn:CsPbBr3 as an absorber and carbon as the HTM achieved an impressive power conversion efficiency of 8.95% compared to 6.87% for undoped CsPbBr3; moreover, it displayed admirable stability in an open-air atmosphere for an operational period of about 720 h without a noticeable negative result. The introduction of the Sn ion may advance the interface extraction of charge between the electric transport layer to the absorber layer and absorber to the carbon electrode. Accordingly, the Sn ion doping on CsPbBr3 during the synthesis phase and the direct evaporation paves a novel approach for intended photovoltaic applications.

Full text of DOI:10.1039/d0ra09202a

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PAPER
Direct deposition of Sn-doped CsPbBr perovskite
3
for efficient solar cell application†
Cite this: RSC Adv., 2021, 11, 3380
ab
a
a
a
a
Mukerem Helil Abib, Junchun Li, Heming Yang, Man Wang, Taotao Chen,
a
ac
EnzeXu and Yang Jiang
*
3
All inorganic carbon-based planar perovskites, particularly CsPbBr , have attracted considerable attention
due to their excellent stability against oxygen, moisture, and heat for photovoltaic utilization. However,
the power conversion efficiency of carbon-based planar CsPbBr perovskite solar cells is mostly low,
3
primarily because of the inferior film quality with undesirable crystallization and narrow light absorbance
ranges. Herein, we develop a novel direct deposition approach combined with Sn doping to achieve
highly efficient and stable carbon-based Sn-doped CsPbBr
doped CsPbBr perovskite powder was effectively synthesized and characterized via a facile strategy by
adding hydrohalic acid in the CsBr, PbBr and SnBr precursor in a dimethyl sulfoxide solution. Moreover,
using the as-synthesized CsPbBr and Sn-doped CsPbBr perovskite powder, PSCs were obtained via
effective direct thermal evaporation. A smooth, constant and pinhole-free perovskite film was achieved
with a configuration of FTO/TiO /Sn:CsPbBr /carbon. PSCs based on Sn:CsPbBr as an absorber and
carbon as the HTM achieved an impressive power conversion efficiency of 8.95% compared to 6.87% for
undoped CsPbBr ; moreover, it displayed admirable stability in an open-air atmosphere for an
3
perovskite solar cells. Mass-scale Sn ion-
3
2
2
3
3
2
3
3
3
Received 29th October 2020
Accepted 15th December 2020
operational period of about 720 h without a noticeable negative result. The introduction of the Sn ion
may advance the interface extraction of charge between the electric transport layer to the absorber layer
DOI: 10.1039/d0ra09202a
3
and absorber to the carbon electrode. Accordingly, the Sn ion doping on CsPbBr during the synthesis
rsc.li/rsc-advances
phase and the direct evaporation paves a novel approach for intended photovoltaic applications.
et al. reported CsPbBr all inorganic PSCs using carbon as an
electrode and realized long-term permanency for >3000 h in an
3
Introduction
Inorganic perovskite solar cells (PSCs) with CsPbX
or mixed) have been a hot topic in recent years because of their conditions (T ¼ 100 C). However, the wide bandgap of 2.3 eV
3
(X ¼ I, Br, Cl ambient environment (RH ꢀ 45%) and 700 h under thermal
ꢁ
22
tunable absorption, high carrier mobility and long diffusion affects the light capture, which results in lower limited effi-
1–5
23–25
length. The record efficiency of CsPbI PSCs over 19% showed ciency of 10.17% compared to the hybrid PSCs.
Therefore,
However, identifying a new approach to improve the initial efficiency and
iodine-based inorganic PSCs usually suffer from poor phase stability are important issues to realize practical applications.
3
6
–10
a fascinating potential application in future.
stability because of the phase transition from black to yellow
perovskite phase, which impedes their practical application.
The performance of PSCs depends on the quality of perov-
skite lms. Normally, one- or two-step spin-coating are facile
11,12
Therefore, how to alleviate the phase transition is still a chal- and well-controlled techniques to prepare perovskite lms.
lenge to realize their practical application. Bromide-based Duan et al. used a multi-spin coating technique to prepare the
26
inorganic PSCs provide a smaller ionic radius, which can CsPbBr
3
lm and achieved an impressive PCE of 9.7%.
effectively improve the phase stability, thus resulting in excel- However, the low solubility of CsX and perovskites in an organic
13–21
lent stability against humidity and heat.
For example, Tong solvent and complex Cs–Pb–X phase diagram makes it difficult
to obtain a high-quality perovskite lm and ideal stoichiometric
27
ratio. The evaporation method provides a non-solvent envi-
ronment and uniform deposition on a large scale. By control-
ling the thickness of the initial layer, we can obtain a dense and
uniform perovskite layer, which would benet in reducing
defects and provide a better interface contact. For example,
a
School of Materials Science and Engineering, Hefei University of Technology, Hefei,
2
30009, P. R. China. E-mail: apjiang@hfut.edu.cn; Fax: +86-551-62904358; Tel:
86-551-62904358
+
b
School of Electrical Engineering and Automation, Hefei University of Technology,
Hefei, 230009, P. R. China
c
Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow Tong et al. developed a sequential deposition method to prepare
University, Suzhou, 215123, P. R. China
3 2
the CsPbBr lm by evaporating CsBr and PbBr . Aer simple
annealing, high-quality PSCs lms were achieved and the
†
Electronic supplementary information (ESI) available. See DOI:
0.1039/d0ra09202a
1
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28
corresponding devices exhibited an impressive PCE of >10.9%.
Ltd. Dimethyl sulfoxide (DMSO, $99.5%), ethanol $99.7%,
Although considerable efforts have been made to improve the acetone $99.5%, hydrochloric acid (HCl) and hydrobromic acid
quality of the perovskite lm, the performance is still far away (HBr) were purchased from Sino Pharm Chemical Reagent Co.,
from the limited efficiency.
Ltd. Fluorine-doped tin oxide (FTO) coated conductive glasses
Incorporation of metal ion could effectively improve the with a block resistance of 14 U and light transmittances of
photovoltaic performance of the Pb-based PSCs because it can $90% were purchased from Wuhan Jinge solar energy tech-
suppress the trap states, tune the bandgap and enhance the nology Co., Ltd. All these chemicals were directly utilized
2
9–32
light absorption.
doped CsPbBr PSCs via several step spin coating technique and
the obtained lms showed better charge extraction and trans-
For example, Guo et al. conveyed SnBr
2
-
without additional modication.
3
CsPbBr and Sn doped CsPbBr perovskite synthesis
3
3
3
3
port ability and the PCE can be enhanced from 6.8% to 8.6%.
Recently, Wang et al. reported CoBr -doped CsPbBr PSCs
through a usual spin coating scheme, the resulting CoBr -doped
2
PbBr2 (1.9 mmol) and CsBr (1.9 mmol) powders and 3 mL
dimethyl sulfoxide (DMSO) precursors were rst placed in a ask
2
3
for the CsPbBr perovskite synthesis. Then, the mixture was vigor-
3
CsPbBr
.5% efficiency compared to the pristine 6.8%.
In this work, we proposed a Sn-doped CsPbBr
directly evaporating the Sn-doped CsPbBr perovskite powder.
3
lms photovoltaic performance was enhanced with
ously stirred for half an hour until the solution turned transparent.
Aerward, 3 mL of HBr was dropped in the above solution with
nonstop stirring for 1 h. To remove the unreacted agents or
supernatant, the solution was washed three times by ethanol, fol-
lowed by centrifugation and discarding process. The precipitate
was dried overnight in a vacuum drying oven at moderate
temperature. The same technique was developed to synthesize the
34
8
3
PSCs by
3
We rst synthesized Sn-doped CsPbBr through HBr dropping in
the CsBr, SnBr2 and PbBr2 precursor solution. Then, the Sn:
CsPbBr -based thin lm was formed by thermal evaporation. The
2 3
nal device with a conguration of FTO/TiO /Sn:CsPbBr /carbon
was fabricated aer blade coating the carbon ink. The incorpora-
tion of Sn would improve the quality of perovskite lm with less
voids/pinholes, high crystallinity and environment stability, which
results in an excellent efficiency of 8.95%. This direct evaporation
and Sn doping paved a new strategy to improve the performance of
PSCs using a facile and inexpensive method.
3
3

Sn-doped CsPbBr perovskite by introducing a measured amount of
3
2
SnBr precursor into the ask at the initial step.
Solar cells fabrication
The uorine-doped tin oxide (FTO) coated conductive glasses
were cleaned using a cleansing agent, ionized water, acetone,
2
and ethanol, in an ultrasonic machine. TiO thin lms were
deposited by spin-coating the titanium isopropoxide precursor
Materials and methods
Chemicals
solution at 2000 rpm for 40 s. Then, the pre-synthesized lms
ꢁ
were annealed at 500 C for 30 min in air and allowed to naturally
Chemicals consumed in this experimentation are itemized as cool down. Then, the samples were treated by 40 mM TiCl
4
and
ꢁ
follows: lead(II) bromide (PbBr
bromide (CsBr, purity $99.9%) were bought from Xi'an polymer previous works.
light technology corp. Tin (II) bromide (SnBr , 99.2%) product doped CsPbBr
was acquired from Alfa Aesar. Titanium diisopropox- vacuum deposition. The FTO/TiO
2
, purity >99.99%) and cesium annealed again at 500 C for another 30 min as mentioned in our
35,36
By using the as-synthesized CsPbBr
perovskite powders, thin lms were fabricated by
substrates were xed on the
3
and Sn-
2
3
2
idebis(acetylacetonate) (75 wt%) in isopropanol was purchased holder and perovskite powders were placed in the heating boat.
ꢃ4
from Sigma-Aldrich. Titanium tetrachloride (TiCl 99.0%) was When the vacuum degree of deposition system reached to 8 ꢂ 10
4
purchased from Shanghai Aladdin Biochemical Technology Co., Pa, the heat source was started to heat. A high-quality lm was
3
Fig. 1 The schematic diagram of the synthesis of Sn:CsPbBr perovskite through a facile scheme by dropping hydrohalic acid into the precursor
solution.
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Fig. 2 (a) The XRD patterns of as-synthesized perovskites powder at different Sn ion doping concentrations respectively, (b) the XPS spectra of as
3 3
synthesized undoped CsPbBr and Sn doped CsPbBr perovskite and (c–f) the corresponding spectrum of Cs 3d, Pb 4f, Br 3d and Sn 3d
respectively.
deposited on the TiO
2
-coated FTO glass with an evaporation rate of ray diffraction arrangements. Moreover, a Hitachi SU8020
ꢃ1
ꢁ
ꢀ
0.5 A˚ s . Then, the pre-deposited lms were annealed at 250 C in scanning electron microscope (SEM) was used for investigating
air for 10 min. Finally, commercial carbon ink was coated as the surface morphologies. To examine the device performance,
a counter electrode using a doctor blade method with active area of photocurrent density–voltage (J–V) characterization measure-
2
ꢁ
0
.09 cm annealed at 90 C for one hour in the open air.
3
ments of undoped and Sn ion-doped CsPbBr solar cells were
obtained under a xenon lamp solar simulator with one sun
ꢃ2
illumination (100 mW cm ). Note that J–V curves were
Characterizations
collected using a Keithley 2636 system source meter per
a scanning frequency of 100 mV s . All measurements were
carried out at room temperature in open air.
ꢃ1
The optical properties, including uorescence and absorption
range, were characterized using the F-4600 uorescence Hitachi
spectrophotometer and UV-2550, UV-vis Shimadzu spectro-
photometer, respectively. X-ray photoelectron spectroscopy
Results and discussion
(XPS) was used to measure the elemental composition of
undoped and Sn ion-doped CsPbBr perovskites. For structural The synthesis of environmentally stable, mass-scale undoped
3
characterization, Rigaku D/MaxrB by consuming CuKa radia- and Sn ion-doped CsPbBr
3
perovskites was carried out through
tion diffraction at 0.1540 nm was utilized to demonstrate the X- a facile scheme by hydrohalic acid falling on the CsBr, PbBr
2
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Fig. 3 The SEM represent of as-synthesized perovskites powder (a) undoped CsPbBr
3
and (b) Sn doped CsPbBr
3
at different magnification scales.
Fig. 4 (a) The crystal structure, (b and c) band gap energy, (d and e) conductivities, (f and g) dielectric functions and (h and i) density of states
DOS) of CsPbBr and CsPb0.998Sn0.002Br perovskites respectively.
(
3
3
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Fig. 5 (a) Schematic diagram of PSCs through thermal evaporation scheme, (b) picture of the PSCs with a configuration of FTO/TiO
2
/Sn:CsPbBr
3
structure and (c and d) top view of the SEM images of undoped CsPbBr
respectively.
3 3 2
and Sn ion-doped CsPbBr thin-film in FTO/TiO /perovskite structure
and SnBr
2
precursors in DMSO, as shown in Fig. 1. Synthesizing undoped CsPbBr
3
was 14.46/15.35/70.19, respectively. In the same
and corresponding
reduce the voids to improve the quality of perovskite lm. In individual elements of Cs 3d, Pb 4f, Br 3d and Sn 3d are shown in
addition, the incorporation of Sn ion in the CsPbBr perovskites Fig. 2(b–f) in black color. The separated elements of Sn-doped
perovskites by the addition of hydrohalic acid was used to manner, the XPS spectra of Sn-doped CsPbBr
3
37
3
could help in obtaining better crystallinity of the CsPbBr3 CsPbBr were assigned to Cs 3d, Pb 4f, Br 3d and Sn 3d spectra
3
perovskites and alleviate the energy mismatch between CsPbBr3 with their peak binding energies of 724.22, 138.04, 68.08 and
and carbon electrode in these devices.
487 eV, respectively. Aer the doping of Sn, the resulting binding
The X-ray powder diffraction (XRD) patterns of the CsPbBr
3
energies of Pb 4f and Br 3d increased, which resulted in an
perovskites powder with Sn (0%), Sn (0.1%), Sn (0.2%) and Sn improved bonding of the CsPbBr
0.3%) doping concentrations are presented in Fig. 2(a). The could help in the creation of steady and stabilized materials. The
XRD patterns of CsPbBr and Sn:CsPbBr perovskites with atomic proportion of Sn/Cs/Pb/Br in the Sn doped CsPbBr
different Sn ion doping concentrations have strong diffraction surveyed from the XPS spectra were 0.83/17.72/14.55/and 66.9,
3
perovskite. This improvement
(
3
3
3
ꢁ
ꢁ
ꢁ
ꢁ
ꢁ
ꢁ
peaks at 15 , 21 , 30 , 34 , 37 and 43 , which can be assigned to respectively.
the representative peaks of CsPbBr perovskite lattice planes of The scanning electron microscopy (SEM) images of undoped
3
(
001)/(100), (110)/(ꢃ110), (002)/(200), (210)/(201), (211)/(ꢃ121) CsPbBr and Sn doped CsPbBr perovskites powders are dis-
3
3
38,39
and (202)/(ꢃ220) respectively.
Under varying concentrations played in Fig. 3(a and b) at different magnication scale. The
from Fig. 3(a) showed less
of Sn ions, the perovskite materials have a good agreement to SEM images of the undoped CsPbBr
3
the undoped CsPbBr
ciated with the Sn ions. X-ray photoelectron spectroscopy (XPS) doped CsPbBr
was performed to investigate the CsPbBr perovskite without a smaller radius than that of the Pb ion existing in the lattice
and with Sn doping. The XPS of undoped CsPbBr perovskite gap of CsPbBr , and the incorporation of Sn ion maybe regu-
3
without any distinguishable peaks asso- densely distribution compared to the corresponding SEM of Sn
3
perovskite seen from Fig. 3(b). The Sn ion has
3
3
3
and the individual peaks conforming of the Cs 3d, Pb 4f and Br lating the typical dimensions of the CsPbBr3 perovskite.
d are presented in Fig. 2(b–e) in red. The Cs 3d, Pb 4f, and Br 3d Therefore, the dimensions of Sn doped materials become
spectra with their peak binding energy were revealed at 724.2, improved compared to the undoped perovskite material and
38.02, and 68.05 eV respectively. Moreover, from the XPS spectra, become signicantly denser.
we have examined that the atomic proportion of Cs/Pb/Br in the
3
1
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Fig. 6 (a) XRD patterns, (b) the diagram of inorganic PSC structure and the corresponding cross-sectional SEM image, (c) optical absorbance and
d) PL emission spectra of undoped and doped thin-film with altered amount of Sn ion.
(
Fig. 7 (a) The J–V curves of undoped and different amounts Sn ion doped perovskite, (b) the best accomplishment J–V devices under forward
and reverse scanning, (c) PCE statistical distribution of without Sn, 0.1% Sn, 0.2% Sn and 0.3% Sn PSCs devices and (d) normalized PCE stability of
undoped and 0.2% Sn doped CsPbBr PSCs devices as a function of storage period under open-air environment respectively.
3
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Table 1 PSCs parameters with different concentrations of Sn ion in perovskite shown in Fig. 4(d). The improvement in conductivity
the perovskite film
of doped perovskite may be ascribed to the alteration of
41
ꢃ2
bandgap energy. Moreover, the undoped CsPbBr and doped
3
Sn ion
VOC [V]
JSC [mA cm
]
FF [%]
PCE [%]
CsPb0.998Sn0.002Br perovskites dielectric functions are revealed
3
Without Sn
1.33
1.39
1.36
1.35
7.08
8.25
9.27
7.65
0.73
0.72
0.71
0.72
6.87
8.26
8.95
7.43
in Fig. 4(f and g). Similar to conductivity, the dielectric func-
tions of doped perovskite increased compared to the undoped
perovskite materials. Fig. 4(h and i) shows the density of states
0
0
0
.1% Sn
.2% Sn
.3% Sn
(DOS) of the optimized structure of CsPbBr
3
and CsPb0.998-
Sn0.002Br
3
perovskites. Based on this analysis, the incorporation
of small amounts of Sn could signicantly improve the photo-
voltaic properties of all the inorganic perovskites.
Theoretical schemes are employed using rst principle
calculations within the supportive system of generalized
gradient approximation (GGA) and Perdew–Burke–Ernzerhof
To further understand the Sn doping in perovskites, we
fabricated PSCs using undoped and doped CsPbBr
powder as precursor materials via direct thermal evaporation
Fig. 5(a)). Pinholes-free perovskite thin lm was deposited on
the TiO -coated FTO glass. Fig. 5(b) shows the image of FTO/
TiO /Sn:CsPbBr
3
perovskite
(
PBE) functionals. The calculated band-gap energy of the opti-
mized structure of CsPbBr perovskites
were 2.3 eV and 2.2 eV, respectively, which suggested that the
(
3
and CsPb0.998Sn0.002Br
3
2
33,40
2
3
substrate aer thermal evaporation and post-
annealing at 250 C for 10 min. Smooth, constant and
incorporation of Sn could tune the band gap energy.
The
ꢁ
schemes were achieved with the energy cutoff of 220 eV, and the
ꢃ5
pinhole-free PSCs lms are obtained through a proper deposi-
total energy of 2 ꢂ 10 eV per atom with a maximum force of
ꢃ1
tion state. Top view SEM images of the undoped CsPbBr
Sn-doped CsPbBr perovskite thin-lm are presented in Fig. 5(c)
and (d), respectively. From the SEM images, we could determine
that certain voids and pinholes existed in the undoped CsPbBr
3
and
˚
0
.05 eV A . Fig. 4(b and c) shows the calculated band gap
3
energy of the optimized structure of CsPbBr
perovskites. Fig. 4(d and e) shows the conductivity of
the undoped CsPbBr and doped CsPb0.998Sn0.002Br perov-
3
and CsPb0.998-
Sn0.002Br
3
3
3
3

lm layer, as shown in Fig. 5(c). From the gure, the interme-
skites. The calculated conductivity of the doped perovskite in
Fig. 4(e) was greater compared to the undoped CsPbBr3
3
diate grain size of the undoped CsPbBr perovskite lm was
reported to decrease compared to the doped perovskite lm. In
Fig. 8 (a and b) X-ray photoelectron spectroscopy (XPS) spectra of Pb4f and Br3d without and with Sn ion CsPbBr
spectra of CsPbBr films without and with Sn and inside the low binding energy and high binding energy cutoff boundary (d) the IPCE spectra of
solar cell device without and with Sn ion.
3
perovskite films (c) the UPS
3
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Table 2 PCE performance of CsPbBr
3
perovskite solar cells in a former report
Method
Device structure
PCE [%]
Reference
Evaporation
Evaporation
Evaporation
Evaporation
Evaporation
Evaporation
Laser deposition
Solution
FTO/c-TiO
FTO/c-TiO
FTO/c-TiO
FTO/c-TiO
FTO/c-TiO
FTO/c-TiO
FTO/c-TiO
FTO/c-TiO
FTO/c-TiO
FTO/c-TiO
2
2
2
2
2
2
2
2
2
2
/Sn doped CsPbBr
3
/carbon
8.95
7.09
8.65
8.34
6.95
9.01
6.30
8.87
8.20
8.63
8.57
This work
5
/CsPbBr
/CsPbBr
/CsPbBr
/CsPbBr
/CsPbBr
3
3
3
3
3
/carbon/CNT/MXene
/spiro-OMeTAD/Au
20
43
19
44
15
1
17
33
34
-CsPb
/spiro-OMeTAD/Au
/Ti -MXene/carbon
2 5
Br /spiro-OMeTAD/Ag
3 2
C
/m-TiO
/m-TiO
/m-TiO
/m-TiO
2
2
2
2
/CsPbBr
/CsPbBr
3
/spiro-OMeTAD/Ag
/carbon-PANi/G
3
Solution
Solution
Solution
/CQDs/CsPbBr
/SnBr doped CsPbBr
/spiro-OMeTAD/Au
3
/RPQDs/carbon
2
3
/carbon
ITO/TiO
2
/CoBr
2
doped CsPbBr
3
ꢃ2
contrast, a pinhole- and void-free full coverage lm was of 7.08 mA cm , 1.33 V and 0.73, respectively. Through Sn ion
observed aer the doping of Sn ion, as presented in Fig. 5(d). doping with different concentrations, the PCE of devices and other
Moreover, the corresponding intermediate grain size of the Sn parameters were enhanced. Thus, aer doping with Sn (0.2%), the
ion-doped CsPbBr
3
perovskite lm was enhanced compared to PCE value of the PSCs was increased to about 8.95% with Jsc of 9.27
ꢃ2
the pristine perovskite lm. The intermediate grain size of the mA cm , Voc of 1.36 V and FF of 0.71. Using a similar technique
undoped CsPbBr
3
lm, as shown in Fig. S1a,† was close to 1.04 PCE of the PSCs at 0.1% Sn doping concentration was calculated
ꢃ2
mm. The corresponding intermediate grain size of the Sn ion- about 8.26% with Jsc of 8.25 mA cm , Voc of 1.39 V and FF of 0.72.
doped CsPbBr
3
lm, as shown in Fig. S1b,† was 1.14 mm. Moreover, at 0.3% Sn doping concentration, the calculated PCE of
ꢃ2
When the Sn ion was introduced in CsPbBr lm, the voids and the PSCs was about 7.43% with Jsc of 7.65 mA cm , Voc of 1.35 V
3
pinholes reduced, and thus perhaps the minor crystal grains and FF of 0.72. The current density to voltage curvature for
could ll-in the gap/voids between the large crystals grains, without/with Sn at different amounts along with the power
which condenses the pinholes of the perovskite layer and thus conversion efficiency (PCE) and related solar cells parameters,
33
the continuity of the lm was enhanced.
Fig. 6(a) shows the XRD patterns of undoped FTO/TiO
CsPbBr and Sn-doped FTO/TiO /Sn:CsPbBr thin lm with
such as current density, open-circuit voltage and ll factor, are
discussed in Table 1.
2
/
3
2
3
Therefore, the introduction of Sn ion might develop inter-
different concentrations of Sn ion. The XRD designs of undoped face extraction of charge between the electron transport layer to
FTO/TiO /CsPbBr and Sn doped FTO/TiO /Sn:CsPbBr3 thin perovskite and perovskite to the carbon. Fig. 7(b) shows the best
2
3
2

lm with different concentrations of Sn ion have similarity with accomplished J–V devices under forward and reverse scanning
the perovskite XRD discussed above, with the difference being voltage is presented in with the calculated PCE value of 8.64%
ꢁ
ꢁ
that the lm XRD have diffraction peaks at 26 , and 51 , which under forward and 8.95% under reverse scanning. The statis-
was related to the conductive FTO substrates. Fig. 6(b) shows tical distribution of PSCs parameters for pristine and Sn doped
the PSCs structure with a conguration of FTO/TiO
2
/Sn:CsPbBr
3
/
devices for a set of ten solar cells in Fig. 7(c) and S2† shows
carbon and the corresponding cross-sectional SEM image. Fig. 6(c) a slight deviation and high reproducibility via the direct depo-
shows the optical absorbance spectra of the undoped and doped sition method described in this study.
CsPbBr3 thin-lm with different quantities of Sn ion. The
Moreover, higher stability under continual thermal and
absorption peaks of the CsPbBr perovskite thin lm with different ambient air occurrence is a determined asset to be used in the
3
quantities of Sn ion doping was slightly shied to the higher commercial utilization of the PSCs devices. The solar cell's
wavelength compared with the pristine CsPbBr
3
perovskite thin- performances for the undoped CsPbBr
3
and 0.2% Sn doped
lm absorption peaks. Similarly, Fig. 6(d) shows the photo- CsPbBr
3
constructed PSCs in air is characterized over 720 h.
luminescence (PL) spectra of the undoped and doped CsPbBr
lm with different quantities of Sn ion.
To realize the effect of Sn ion on the performance of CsPbBr
3
thin Normalized solar cells PCE with storage time revealed in

Fig. 7(d) are approximately unaffected over an operational
3
period of 720 h. The result shown in Fig. 7(d) and aer intro-
solar cells, we introduced different amounts of Sn ion into the ducing Sn ions in the direction of the CsPbBr matrix, there is
3
pure CsPbBr -based solar cells. Fig. 7(a) shows the current no noticeable negative result on the stability of the conforming
3
density to voltage curvature of the undoped and Sn ion-doped at device, even for slight advanced withholding values upon
different doping amounts. Power conversion efficiency (PCE) persistent open environment exposure compared to the undo-
and related solar cells parameters such as current density, open- ped device performances. Recently, researchers presented that
circuit voltage and ll factor were calculated for undoped and the environmental stability of all-inorganic perovskite solar
Sn ion-doped perovskite solar cells. Fig. 7(a) shows the calcu- cells performance is enhanced by metal ions doping due to
42
lated PCE value of the undoped PSCs is about 6.87%, with lattice reduction. The incident photon-to-electron conversion
current density (J ), open-circuit voltage (V ) and ll factor (FF) efficiency (IPCE) spectrum of the devices presented in Fig. 8(d)
sc
oc
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show that the absorbable wavelength range of the pristine and Province of China (Grant No. 1704a0902023), and the Funda-
with Sn introduced devices plateau between 350 and 530 nm. mental Research Funds for the Central Universities (No.
The maximum IPCE of about 80% was obtained in the wave- JZ2019HGBH0202) for the nancial support.
length range of 350 to 530 nm.
To understand the alteration of the bond energy of Pb and Br
aerward introducing the Sn ion, we measured the XPS spectra
to illustrate the perovskite lm without and with Sn ion. The
introduction of Sn ion in the perovskite lattice results in an
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©
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RSC Adv., 2021, 11, 3380–3389 | 3389