INFLUENCE OF THE SOLVENT AND THE RATIO OF STARTING REAGENTS ON THE PROPERTIES OF ORGANIC-INORGANIC PEROVSKITE MAPbI3
The peculiarities of formation and properties of organiс-inorganic MAPbI3 perovskite films, obtained from solutions with different ratios of starting reagents (PbI2:MAI = 1:1,1:2, and 1:3), in the DMF and DMSO solvents, studied. As the PbI2:MAI ratio increases, the temperature of the formation of a...
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Ukrainian Chemistry Journal| _version_ | 1871465820767387648 |
|---|---|
| author | Torchyniuk, Pavlo V'yunov, Oleg Vlasyuk, Viktor Kostylyov, Vitaliy Belous, Anatolii |
| author_facet | Torchyniuk, Pavlo V'yunov, Oleg Vlasyuk, Viktor Kostylyov, Vitaliy Belous, Anatolii |
| author_institution_txt_mv | [
{
"author": "Pavlo Torchyniuk",
"institution": "V.I. Vernadsky Institute of General and Inorganic Chemistry of National Academy of Sciences of Ukraine, Palladina ave., 32\/34, Kyiv, 03142, Ukraine mob. phone. (+38099) 727-98-06"
},
{
"author": "Oleg V'yunov",
"institution": "Candidate of Chemical Sciences, Senior Researcher, V.I. Vernadsky Institute of General and Inorganic Chemistry of National Academy of Sciences of Ukraine, Palladina ave., 32\/34, Kyiv, 03142,"
},
{
"author": "Viktor Vlasyuk",
"institution": "Researcher, V. E. Lashkarev Institute of Semiconductor Physics of National Academy of Sciences of Ukraine, pr. Nauki 41, Kyiv, 03028"
},
{
"author": "Vitaliy Kostylyov",
"institution": "Doctor of Physical and Mathematical Sciences, Senior Researcher, V. E. Lashkarev Institute of Semiconductor Physics of National Academy of Sciences of Ukraine, pr. Nauki 41, Kyiv, 03028"
},
{
"author": "Anatolii Belous",
"institution": "Doctor of Chemical Sciences, Professor, Academician of NAS of Ukraine V.I. Vernadsky Institute of General and Inorganic Chemistry of National Academy of Sciences of Ukraine, Palladina ave., 32\/34, Kyiv, 03142, "
}
] |
| author_sort | Torchyniuk, Pavlo |
| baseUrl_str | https://ucj.org.ua/index.php/journal/oai |
| collection | OJS |
| datestamp_date | 2026-07-22T08:23:49Z |
| description | The peculiarities of formation and properties of organiс-inorganic MAPbI3 perovskite films, obtained from solutions with different ratios of starting reagents (PbI2:MAI = 1:1,1:2, and 1:3), in the DMF and DMSO solvents, studied. As the PbI2:MAI ratio increases, the temperature of the formation of a single-phase MAPbI3 perovskite film also increases. The slight changes in the structural and electrophysical characteristics for perovskite films obtained at the  different ratios of PbI2:MAI in DMF and DMSO were found. These changes are related to the solvent that is included in the crystalline structure of perovskite. In the same ratios of starting reagents, DMF is included in the structure of perovskite in a greater amount than DMSO. |
| doi_str_mv | 10.33609/2708-129X.88.04.2022.79-93 |
| first_indexed | 2025-09-24T17:43:44Z |
| format | Article |
| fulltext |
79
UCD: 539.216:546.817:548.736.442.6 doi: 10.33609/2708-129X.88.04.2022.79-93
INFLUENCE OF THE SOLVENT AND THE RATIO OF STARTING REAGENTS
ON THE PROPERTIES OF ORGANIC-INORGANIC PEROVSKITE MAPbI3
Torchyniuk P.V.1, V’yunov O.I.*1, Vlasiuk V.M.2, Kostylyov V.P.2, Belous A.G.1
1V.I. Vernadsky Institute of General and Inorganic Chemistry of National Academy of Sciences of
Ukraine, Acad. Palladina Ave., 32/34, Kyiv 03142, Ukraine
2V.E. Lashkarev Institute of Semiconductor Physics of National Academy of Sciences of Ukraine,
pr. Nauki 41, Kyiv 03028, Ukraine
* e-mail: vyunov@ionc.kiev.ua
The peculiarities of formation and properties of organiс-inorganic MAPbI3 perovskite
films, obtained from solutions with different ratios of starting reagents (PbI2:MAI = 1:1,1:2,
and 1:3), in the DMF and DMSO solvents, studied. As the PbI2:MAI ratio increases, the
temperature of the formation of a single-phase MAPbI3 perovskite film also increases.
The slight changes in the structural and electrophysical characteristics for perovskite films
obtained at the different ratios of PbI2:MAI in DMF and DMSO were found. These changes
are related to the solvent that is included in the crystalline structure of perovskite. In the same
ratios of starting reagents, DMF is included in the structure of perovskite in a greater amount
than DMSO.
Keywords: organic-inorganic perovskite, phase transformations, structural parameters,
electrophysical characteristics.
INTRODUCTION. The global energy crisis
is one of the greatest challenges facing human-
ity. It is necessary to develop new technologies
for the successful use of energy from renew
able sources due to the reduced availability of
fossil fuels. Solar energy is a rich, freely avail-
able source and promising replacement for
non-renewable fossil fuels.
The solar cells based on organic-inorgan-
ic perovskites have attracted the attention of
scientists according to a significant increase
in efficiency to 25.2%, low cost, and ease of
production. [1–2]. This effect was achieved
by improving the design of solar cells, adding
new conductive layers (of n- and p-type), and
improving the quality of the perovskite films.
Organic-inorganic perovskites combine the ad-
vantages of organic and inorganic semiconduc-
tors: high optical absorption, high mobility of
charge carriers [3], and regulated bandgap [4].
Photoactive halide perovskites usually ex-
hibit a three-dimensional crystal structure
with the characteristic chemical formula ABX3,
where A is a monovalent cation of methyl-
ammonium (CH3NH3
+), formamidinium
(HC(NH2)2
+), cesium (Cs+) or rubidium (Rb+),
80 ISSN 2708-129X. Укр. хім. журн., 2022
INFLUENCE OF THE SOLVENT AND THE RATIO OF STARTING REAGENTS ON THE PROPERTIES
OF ORGANIC-INORGANIC PEROVSKITE MAPbI3INORGANIC CHEMISTRY
and B is a divalent metal cation Pb2+ or Sn2+,
and X is a halide anion (Cl-, Br- or I-) [5, 6].
Achieving the high photoelectric character-
istics of organic-inorganic perovskite depends
on the nucleation and growth of crystal pro-
cesses. As a result of the process control, it is
possible to obtain a smooth and compact film
of perovskite. External factors (temperature,
moisture, oxygen), as well as solvent, methods
of obtaining films, and annealing can signifi-
cantly affect the structural and physical pro
perties of organic-inorganic perovskite. It is
known that solvents (DMF, DMSO, γ-buty
rolactone (GBL), NMP) [7, 8] were used for
the synthesis of perovskites can affect the pro
perties of films.
Changes in the synthesis conditions (ratio
of starting reagents and solvent) may affect the
properties of perovskites. It was shown that the
ratio of starting reagents PbI2:MAI (CH3NH3I)
affects electrophysical characteristics, particu-
larly, the bandgap [9]. Solvent replacement
also affects the properties of organic-inorganic
perovskite. An increase in the stability of films
to moisture and the mobility of charge carriers
detected by using dimethyl sulfoxide instead
of dimethylformamide during the synthesis of
perovskite [10].
The method of obtaining perovskites is a
key factor in achieving high characteristics
(surface coverage, crystallinity, thickness, and
quality of films responsible for the morpho-
logical and transport properties of perovskite).
Several methods can be used to obtain films of
organic-inorganic perovskites. The most com-
mon methods of them are one-step and two-
step deposition, spin-coating, the method of
rapid deposition crystallization, and thermal
evaporation.
It is known that organic-inorganic perov
skites are unstable materials that can degrade
and decompose into various components un-
der the influence of external factors. Finding
ways to increase the stability of perovskites is
an urgent task, as its solution will allow them
to be used in the large-scale creation of solar
cells. Nowadays, the best laboratory samples
of elements based on perovskite demonstrate
high efficiency and a low cost of their produc-
tion. However, they have relatively low stabili-
ty, although some solar cells show stable ope
ration throughout the year [11, 12].
This work aims to study the peculiarities of
perovskite formation, and structural and elec-
trophysical characteristics of organic-inorga
nic MAPbI3 perovskite films depending on the
solvent and the ratio of starting reagents.
EXPERIMENT AND DISCUSSION OF
THE RESULTS.
Materials. Lead iodide (PbI2) and methyl
ammonium iodide MAI (CH3NH3I) were
used as starting reagents for the synthesis of
organic-inorganic perovskites. To stabilize the
structure of perovskite, partial replacement of
iodine with chlorine was carried out by adding
chemically pure methylammonium chloride
MACl (CH3NH3Cl). Dried chemically pure
dimethylformamide (DMF) and dimethyl sulf
oxide (DMSO) were used as solvents.
The starting reagents PbI2 and MAI in the
ratios 1:1, 1:2, 1:3 were dissolved in DMF and
DMSO and stirred at 70 °C for 1 hour to obtain
MAPbI3 (CH3NH3PbI3) films. The formation
of crystalline MAPbI3 films was performed
in a dry box. A pre-prepared clear solution
was deposited on cleaned glass substrates by
spin-coating at a speed of 1200 rpm for 30 s.
The heat treatment of the films was performed
on a preheated stove at temperatures from
20 to 205 °C for 15 minutes.
81https://ucj.org.ua
Torchyniuk P.V., V’yunov O.I., Vlasyuk V.M., Kostylyov V. P., Belous A.G. UCJ № 4 / Vol. 88
The identifications of the phase composition
of films and calculations of the parameters of
the unit cell were performed by X-ray diffrac-
tometry (XRD) using a DRON-4-07 (CuKα
radiation and Ni filter, 40 kV, 18 mA) at 2Θ =
5–50º, a step of 0.04º and a count time of 4 s.
SiO2 (angle standard 2Θ) and Al2O3 (cer-
tified intensity standard) were used as stand-
ards [13]. The parameters of the unit cell and
the coordinates of atoms were determined us-
ing the FullProf program developed by Juan
Rodríguez-Carvajal, Laboratoire Léon Bril-
louin (France) [14].
Peculiarities of phase transformations in
the formation of organic-inorganic perovskite
MAPbI3 in DMF, DMSO solvents. Plots of the
percentage of crystalline phases versus the film
treatment temperature were constructed based
on diffractograms of perovskite films obtained
at different ratios of starting reagents in the
DMF solvent (Fig. 1).
Figure 1 shows that the temperature rang-
es of the existence of intermediate compounds
(MA)2(DMF)2Pb3I8, (MA)2(DMF)xPbI4, (MA)3
(DMF)PbI5, (MA)2(DMF)2Pb2I6 and organic-in-
organic perovskite MAPbI3 in the film can be
determined depending on the ratio of reagents.
The structure of MAPbI3 perovskite begins to
form at a temperature of 20-25 °C, regardless of
the ratio of starting reagents. The formation of
organic-inorganic perovskite occurs by the for-
mation and decomposition of various amounts
of intermediate compounds. At the ratio of
starting reagents PbI2:MAI – 1:1, there are three
intermediate compounds, and at 1:2, 1:3 four
and two intermediate compounds, respectively.
In a detailed analysis of the percentage of crys-
talline phases and diffractograms, formation re-
actions of MAPbI3 perovskite were obtained at
the PbI2:MAI = 1:1 ratio in DMF (Table 1).
Fig. 1. The dependence of the percentage of
crystalline phases on the treatment temperature
of the film obtained at different ratios PbI2:MAI in
DMF: a) 1:1; (b) 1:2; (с) 1:3.
3
Fig. 1. The dependence of the percentage of crystalline phases on the treatment temperature of the film
obtained at different ratios PbI2:MAI in DMF: a) 1:1; (b) 1:2; (с) 1:3.
Figure 1 shows that the temperature ranges of the existence of intermediate compounds
(MA)2(DMF)2Pb3I8, (MA)2(DMF)xPbI4, (MA)3(DMF)PbI5, (MA)2(DMF)2Pb2I6 and organic-inorganic
perovskite MAPbI3 in the film can be determined depending on the ratio of reagents. The structure of
MAPbI3 perovskite begins to form at a temperature of 20-25 °C, regardless of the ratio of starting reagents.
The formation of organic-inorganic perovskite occurs by the formation and decomposition of various
amounts of intermediate compounds. At the ratio of starting reagents PbI2:MAI – 1:1, there are three
intermediate compounds, and at 1:2, 1:3 four and two intermediate compounds, respectively. In a detailed
analysis of the percentage of crystalline phases and diffractograms, formation reactions of MAPbI3
perovskite were obtained at the PbI2:MAI = 1:1 ratio in DMF (Table 1).
Table 1
Phase transformations in the formation of MAPbI3 perovskite at a ratio of starting reagents of 1:1 in
DMF.
Reagents Temperature Reaction products
20-45 °C (MA)3(DMF)PbI5 + (MA)2(DMF)xPbI4 + 2MAPbI3 +
3(MA)2(DMF)2Pb3I8
50 °C 0,5(MA)3(DMF)PbI5 + 0,75(MA)2(DMF)xPbI4 +
1,25MAI + 3(MA)2(DMF)2Pb3I8 + 2,75MAPbI3
82 ISSN 2708-129X. Укр. хім. журн., 2022
INFLUENCE OF THE SOLVENT AND THE RATIO OF STARTING REAGENTS ON THE PROPERTIES
OF ORGANIC-INORGANIC PEROVSKITE MAPbI3INORGANIC CHEMISTRY
Table 1
Phase transformations in the formation of MAPbI3 perovskite at a ratio of starting
reagents of 1:1 in DMF.
Reagents Temperature Reaction products
13PbI2 + 13MAI
(1:1 in DMF)
20–45 °C (MA)3(DMF)PbI5 + (MA)2(DMF)xPbI4 + 2MAPbI3 +
3(MA)2(DMF)2Pb3I8
50 °C 0.5(MA)3(DMF)PbI5 + 0.75(MA)2(DMF)xPbI4 + 1.25MAI
+ 3(MA)2(DMF)2Pb3I8 + 2.75MAPbI3
55°C 0.5(MA)2(DMF)xPbI4 + 2.5(MA)2(DMF)2Pb3I8 + 2MAI +
5MAPbI3
> 55–105 °C (MA)2(DMF)2Pb3I8 + 10MAPbI3 + MAI
>105–110 °C 0.5(MA)2(DMF)2Pb3I8 + 11MAPbI3 + MAI +0.5PbI2
> 110–115 °C 13 MAPbI3
13PbI2 + 13MAI 20–45° C (MA)3(DMF)PbI5 + (MA)2(DMF)xPbI4 + 2MAPbI3 +
3(MA)2(DMF)2Pb3I8
(MA)3(DMF)PbI5
50 °C
0.5(MA)3(DMF)PbI5 + 0.5(MA)2(DMF)xPbI4 + 0.5MAI +
(0.5-0.5x)DMF
2(MA)2(DMF)xPbI4 0.25(MA)2(DMF)xPbI4 + 0.75MAPbI3 + 0.75MAI +
1.5xDMF
0.5(MA)3(DMF)PbI5
55 °C
0.5(MA)2(DMF)xPbI4 + 0.5MAI + (0.5-0.5x)DMF
0.75(MA)2(DMF)xPbI4 0.75MAPbI3 + 0.75MAI + 0.75xDMF
3(MA)2(DMF)2Pb3I8 +
0.5MAI
2.5(MA)2(DMF)2Pb3I8 + 1,5MAPbI3 + 2DMF
0.5(MA)2(DMF)xPbI4
>55-105 °C
0.5MAPbI3 + 0.5MAI + 0.5xDMF
2.5(MA)2(DMF)2Pb3I8 +
0.5MAI
(MA)2(DMF)2Pb3I8 + 4.5MAPbI3 + 3DMF
(MA)2(DMF)2Pb3I8 > 105–110 °C 0.5(MA)2(DMF)2Pb3I8 + MAPbI3 + 0.5PbI2 + DMF
0.5(MA)2(DMF)2Pb3I8 +
0.5MAI > 110–115 °C
1,5MAPbI3 + DMF
0.5PbI2 + 0.5MAI 0.5MAPbI3
At a ratio of 1:1, a single-phase perovskite
film is formed at 115 °C. There is a gradual de-
composition of the intermediate compound
(MA)3(DMF)PbI5 into (MA)2(DMF)xPbI4,
which completely decomposes into MAPbI3 at
T> 55 °C. The compound (MA)2(DMF)2Pb3I8
is completely decomposed into MAPbI3 pe
rovskite at T> 110 °C.
When the ratio of starting reagents is 1:2 in
DMF, a single-phase MAPbI3 perovskite film is
formed at 170 °C (Table 2). At this ratio, sim-
ilar transformations of the intermediate com-
pounds (MA)3(DMF)PbI5, (MA)2(DMF)xPbI4,
(MA)2(DMF)2Pb3I8 are observed for the ratio
1:1, but the temperatures of transformations
are greatly different. In addition, the conver-
sion of the intermediate (MA)2(DMF)2Pb2I6 to
MAPbI3 is observed in this system at T> 30 °C.
83https://ucj.org.ua
Torchyniuk P.V., V’yunov O.I., Vlasyuk V.M., Kostylyov V. P., Belous A.G. UCJ № 4 / Vol. 88
Table 2
Phase transformations in the formation of MAPbI3 perovskite at a ratio of starting
reagents of 1:2 in DMF.
Reagents Temperature Reaction products
24PbI2 + 48MAI
(1:2 in DMF)
20 °C 4(MA)2(DMF)2Pb2I6 + 2(MA)3(DMF)PbI5 + 20MAI +
3(MA)2(DMF)xPbI4 + 3(MA)2(DMF)2Pb3I8 + 2MAPbI3
25 °C 3(MA)2(DMF)2Pb2I6 + (MA)3(DMF)PbI5 + 20MAI +
4(MA)2(DMF)xPbI4 + 2(MA)2(DMF)2Pb3I8 + 7MAPbI3
>30–130 °C 3(MA)2(DMF)xPbI4 + 0.5(MA)3(DMF)PbI5 + 20MAI +
20.5MAPbI3
>130–160 °C 2.5(MA)2(DMF)xPbI4 + 21.5MAPbI3 + 21.5MAI
>160–170 °C 24MAPbI3 + 24MAI
24PbI2 + 48MAI 20 °C 4(MA)2(DMF)2Pb2I6 + 2(MA)3(DMF)PbI5 + 3(MA)2(DMF)
xPbI4 + 3(MA)2(DMF)2Pb3I8 + 2MAPbI3 + 20MAI
4(MA)2(DMF)2Pb2I6
25 °C
3(MA)2(DMF)2Pb2I6 + 2MAPbI3 + 2DMF
2(MA)3(DMF)PbI5 (MA)3(DMF)PbI5 + (MA)2(DMF)xPbI4 + МАІ + (1-x)DMF
3(MA)2(DMF)2Pb3I8 +
MAI
2(MA)2(DMF)2Pb3I8 + 3MAPbI3 + 2DMF
3(MA)2(DMF)2Pb2I6
>30–130 °C
6MAPbI3 + 6DMF
(MA)3(DMF)PbI5 0.5(MA)3(DMF)PbI5 + 0.5(MA)2(DMF)xPbI4 + 0.5МАІ +
(0.5-0.5x)DMF
4(MA)2(DMF)xPbI4 2.5(MA)2(DMF)xPbI4 + 1.5MAPbI3 + 1.5MAI + 1.5xDMF
2(MA)2(DMF)2Pb3I8 +
2MAI
6MAPbI3 + 4DMF
3(MA)2(DMF)xPbI4 >130–160 °C 2(MA)2(DMF)xPbI4 + MAPbI3 + MAI + xDMF
0.5(MA)3(DMF)PbI5 0.5(MA)2(DMF)xPbI4 + 0.5МАІ + (0.5-0.5x)DMF
2.5(MA)2(DMF)xPbI4 >160–170 °C 2.5MAPbI3 + 2.5MAI + 2.5xDMF
Table 3
Phase transformations in the formation of MAPbI3 perovskite at a ratio of starting
reagents of 1:3 in DMF.
Reagents Temperature Reaction products
9PbI2 + 27MAI
(1:3 in DMF)
20–150 °C 4(MA)2(DMF)xPbI4 + (MA)3(DMF)PbI5 + 4MAPbI3 + 12MAI
>150–170 °C 2(MA)2(DMF)xPbI4 + 7MAPbI3 + 16MAI
>170–175 °C 9MAPbI3 + 18MAI
9PbI2 + 27MAI 20–150 °C 4(MA)2(DMF)xPbI4 + (MA)3(DMF)PbI5 + 4MAPbI3 + 12MAI
4(MA)2(DMF)xPbI4 +
(MA)3(DMF)PbI5
>150–170 °C 2(MA)2(DMF)xPbI4 + 4МАІ + 3MAPbI3 + (2x+1)DMF
2(MA)2(DMF)xPbI4 >170–175 °C 2MAPbI3 + 2MAI + 2xDMF
84 ISSN 2708-129X. Укр. хім. журн., 2022
INFLUENCE OF THE SOLVENT AND THE RATIO OF STARTING REAGENTS ON THE PROPERTIES
OF ORGANIC-INORGANIC PEROVSKITE MAPbI3INORGANIC CHEMISTRY
At the ratio PbI2:MAI = 1:3, the formation
of a single-phase MAPbI3 perovskite film oc-
curs at 175 °C (Table 3).
There is a gradual decomposition of the in-
termediate compound (MA)3(DMF)PbI5 into
4MAI and (MA)2(DMF)xPbI4; the latter com-
pletely decomposes into MAPbI3 at T> 170 °C.
Thus, the ratio of starting reagents in DMF
significantly affects the number of intermediate
compounds that are formed during the synthe-
sis. As the ratio of reagents increases, the tem-
perature of formation of single-phase MAPbI3
perovskite film increases. The MAPbI3 phase is
present in the film after heat treatment at 20 °C
in amounts of 15-30 wt. %. However, at high-
er temperatures of 40-60 °C, the intermediate
phases begin to decompose, and in this tempe
rature range, the transformation of the interme-
diate phases into perovskite is not completed.
For the perovskite films synthesized at dif-
ferent ratios of starting reagents in the DMSO
solvent, plots of the crystalline phase content
versus the film treatment temperature were
constructed (Fig. 2).
Figure 2 shows that the structure of MAPbI3
perovskite begins to form at 60 °C for the ra-
tios 1:1, 1:2, and at 70 °C for the ratio 1:3. At
a ratio of 1:1, the perovskite film obtained at
T> 160 °C begins to degrade, which is accom-
panied by a decrease in the percentage of per-
ovskite MAPbI3 and an increase in the percent-
age of the intermediate PbI2∙DMSO (Fig. 2a).
At this ratio of starting reagents, a single-phase
film is not formed. At a ratio of 1:2, 1:3, inter-
mediate compounds completely decompose
and a single-phase MAPbI3 film is formed at
190 and 205 °C, respectively.
The quantitative content of the phases
(MA)2(DMSO)2Pb3I8, (MA)2(DMSO)xPbI4,
PbI2∙DMSO, PbI2∙2DMSO, and organic-inor-
ganic perovskite MAPbI3 in the film depends on
the ratio of reagents and treatment temperature.
Fig. 2. The dependence of the percentage of
crystalline phases on the treatment temperature
of the film obtained at different ratios PbI2:MAI in
DMSO: (a) 1:1; (b) 1:2; (с) 1:3.
6
Fig. 2. The dependence of the percentage of crystalline phases on the treatment temperature of the film obtained at
different ratios PbI2:MAI in DMSO: (a) 1:1; (b) 1:2; (с) 1:3.
The quantitative content of the phases (MA)2(DMSO)2Pb3I8, (MA)2(DMSO)xPbI4, PbI2∙DMSO,
PbI2∙2DMSO, and organic-inorganic perovskite MAPbI3 in the film depends on the ratio of reagents and
treatment temperature.
In a detailed analysis of diffractograms and the phase content of the film, formation reactions of
MAPbI3 perovskite at the ratio PbI2:MAI = 1:1 in DMSO were obtained (Table 4).
Table 4
Phase transformations in the formation of MAPbI3 perovskite at a ratio of starting reagents of 1:1 in
DMSO.
Reagents Temperature Reaction products
10PbI2 + 10MAI
(1:1 in DMSO)
20-50 °C 3(MA)2(DMSO)2Pb3I8 + PbI2∙ 2DMSO + 4MAI
60-85 °C 2(MA)2(DMSO)2Pb3I8 + PbI2∙ 2DMSO + 3MAPbI3 +
3MAI
90 °C (MA)2(DMSO)2Pb3I8+ (MA)2(DMSO)xPbI4 +
6MAPbI3
> 90-100 °C (MA)2(DMSO)2Pb3I8 + 7MAPbI3 + MAI
110 °C 0,5(MA)2(DMSO)2Pb3I8 + 0,5PbI2∙ 2DMSO + MAI +
85https://ucj.org.ua
Torchyniuk P.V., V’yunov O.I., Vlasyuk V.M., Kostylyov V. P., Belous A.G. UCJ № 4 / Vol. 88
Table 4
Phase transformations in the formation of MAPbI3 perovskite at a ratio of starting
reagents of 1:1 in DMSO.
Reagents Temperature Reaction products
10PbI2 + 10MAI
(1:1 in DMSO)
20–50 °C 3(MA)2(DMSO)2Pb3I8 + PbI2∙ 2DMSO + 4MAI
60–85 °C 2(MA)2(DMSO)2Pb3I8 + PbI2∙ 2DMSO + 3MAPbI3 + 3MAI
90 °C (MA)2(DMSO)2Pb3I8+ (MA)2(DMSO)xPbI4 + 6MAPbI3
> 90–100 °C (MA)2(DMSO)2Pb3I8 + 7MAPbI3 + MAI
110 °C 0.5(MA)2(DMSO)2Pb3I8 + 0.5PbI2∙ 2DMSO + MAI +
8MAPbI3
> 110–160 °C 0.5(MA)2(DMSO)2Pb3I8 + 8.5MAPbI3 + 0.5MAI
> 165–180 °C 0.25(MA)2(DMSO)2Pb3I8 + 9MAPbI3 + 0.5MAI +
0.25PbI2∙DMSO
190 °C 0.25(MA)2(DMSO)2Pb3I8 + 7MAPbI3 + 2.25PbI2∙ DMSO +
2.5MAI
10PbI2 + 10MAI 20–50 °C 3(MA)2(DMSO)2Pb3I8 + PbI2∙ 2DMSO + 4MAI
3(MA)2(DMSO)2Pb3I8
+ MAI
60–85 °C 2(MA)2(DMSO)2Pb3I8 + 3 MAPbI3 +
2DMSO
2(MA)2(DMSO)2Pb3I8 +
2MAI 90 °C
(MA)2(DMSO)2Pb3I8 + (2-x)DMSO +
(MA)2(DMSO)xPbI4 + 2MAPbI3
PbI2∙ 2DMSO + MAI MAPbI3 + 2DMSO
(MA)2(DMSO)xPbI4 > 90–100 °C MAPbI3 + MAI + xDMSO
(MA)2(DMSO)2Pb3I8 110 °C 0.5(MA)2(DMSO)2Pb3I8 + MAPbI3 + 0.5PbI2∙ 2DMSO
0.5PbI2∙ 2DMSO + MAI > 110–160 °C 0.5 MAPbI3 + 0.5 MAI + DMSO
0.5(MA)2(DMSO)2Pb3I8
+ 0.5MAI
> 165–180 °C 0.25(MA)2(DMSO)2Pb3I8 + 0.5MAPbI3 + 0.25PbI2∙ DMSO
+ 0.25DMSO
0.25PbI2∙ DMSO +
2MAPbI3
190 °C 2 MAI + 2.25PbI2∙ DMSO
In a detailed analysis of diffractograms
and the phase content of the film, formation
reactions of MAPbI3 perovskite at the ratio
PbI2:MAI = 1:1 in DMSO were obtained (Ta-
ble 4).
At a ratio of starting reagents of 1:1 in
DMSO, the formation of organic-inorganic
perovskite MAPbI3 occurs through the for-
mation and decomposition of 4 intermediates
(MA)2(DMSO)2Pb3I8, (MA)2(DMSO)xPbI4,
PbI2∙DMSO, PbI2∙2DMSO. It was shown that the
intermediate compound (MA)2(DMSO)2Pb3I8
at 90 °C decomposes into the compound
(MA)2(DMSO)xPbI4, from which perovskite
formation takes place.
At a ratio of 1:2 in DMSO, a single-phase
perovskite film is formed at 190 °C (Table 5). In
this case, the same 4 intermediate compounds
are also formed, which are formed at a ratio
of 1:1.
86 ISSN 2708-129X. Укр. хім. журн., 2022
INFLUENCE OF THE SOLVENT AND THE RATIO OF STARTING REAGENTS ON THE PROPERTIES
OF ORGANIC-INORGANIC PEROVSKITE MAPbI3INORGANIC CHEMISTRY
Table 5
Phase transformations in the formation of MAPbI3 perovskite at a ratio of starting rea-
gents of 1:2 in DMSO.
Reagents Temperature Reaction products
8PbI2 + 16MAI
(1:2 in DMSO)
20–55 °C 3(MA)2(DMSO)2Pb3I8 + PbI2∙2DMSO + PbI2∙ DMSO +
12MAI
60–85 °C 2(MA)2(DMSO)2Pb3I8 + PbI2∙DMSO + MAPbI3 + 11MAI
90–140 °C (MA)2(DMSO)2Pb3I8 + PbI2∙DMSO + 3MAPbI3 + 9MAI +
(MA)2(DMSO)xPbI4
>140–160 °C PbI2∙DMSO + 2(MA)2(DMSO)xPbI4 + 5MAPbI3 + 7MAI
165 °C 0.5(MA)2(DMSO)2Pb3I8 + 0.5PbI2∙DMSO + 5MAPbI3 +
(MA)2(DMSO)xPbI4 + 8MAI
>165–185 °C 0.75(MA)2(DMSO)2Pb3I8 + 5.25MAPbI3 + 0.5PbI2∙DMSO
+ 9.25MAI
190 °C 8MAPbI3 + 8MAI
8PbI2 + 16MAI 20–55 °C 2(MA)2(DMSO)2Pb3I8 + PbI2∙2DMSO + PbI2∙DMSO +
12MAI
PbI2∙ 2DMSO 60–85 °C PbI2∙DMSO + DMSO
PbI2∙ DMSO + MAI MAPbI3 + DMSO
2(MA)2(DMSO)2Pb3I8 +
2MAI
90–140 °C (MA)2(DMSO)2Pb3I8 + 2MAPbI3 + (2-x)DMSO +
(MA)2(DMSO)xPbI4
(MA)2(DMSO)2Pb3I8 +
2MAI
>140–160 °C (MA)2(DMSO)xPbI4 + 2MAPbI3 + (2-x)DMSO
2(MA)2(DMSO)xPbI4 +
PbI2∙ DMSO 165 °C
0.5(MA)2(DMSO)2Pb3I8 + 0.5PbI2∙DMSO +
(MA)2(DMSO)xPbI4 + MAI + (x-0.5)DMSO
0.5(MA)2(DMSO)2Pb3I8
+ (MA)2(DMSO)xPbI4
>165-185 °C 0.75(MA)2(DMSO)2Pb3I8 + 0.25MAPbI3 + 1.25MAI + (x-
0.5)DMSO
0.75(MA)2(DMSO)2Pb3I8
+ 1.25MAI 190 °C
2.25 MAPbI3 + 1.5DMSO + 0.5MAI
0.5PbI2∙ DMSO + 0.5MAI 0.5MAPbI3 + 0.5DMSO
At a ratio of 1:2, interconversion of com-
pounds (MA)2(DMSO)2Pb3I8 ↔ (MA)2(DM-
SO)xPbI4 is observed. At low temperatures
(90-160 °C) the preceding reaction proceeds
in the forward direction with the forma-
tion of (MA)2(DMSO)xPbI4, while a part of
(MA)2(DMSO)2Pb3I8 is converted into MAPbI3.
At T > 165-185 °C, the reaction proceeds in the
reverse direction, while a part of (MA)2(DM-
SO)xPbI4 is converted into MAPbI3. A con-
version of the compound PbI2∙2DMSO to
PbI2∙DMSO is also observed, which in interac-
tion with MAI forms perovskite MAPbI3.
When increasing the ratio of starting rea-
gents to 1:3, a single-phase perovskite film is
formed at 205 °C (Table 6). The formation of
87https://ucj.org.ua
Torchyniuk P.V., V’yunov O.I., Vlasyuk V.M., Kostylyov V. P., Belous A.G. UCJ № 4 / Vol. 88
perovskite occurs through the formation and
decomposition of 4 intermediate compounds.
At a ratio of 1:3, interconversion of compounds
(MA)2(DMSO)2Pb3I8 ↔ (MA)2(DMSO)xPbI4
is also observed, but in a wider temperature
range. There is also a conversion of the com-
pound PbI2∙2DMSO to PbI2∙DMSO, which
when interacting with MAI forms perovskite
MAPbI3 as for the ratio 1:2.
Table 6
Phase transformations in the formation of MAPbI3 perovskite at a ratio of starting
reagents of 1:3 in DMSO.
Reagents Temperature Reaction products
8PbI2 + 24MAI
(1:3 in DMSO)
20–30 °C 2(MA)2(DMSO)2Pb3I8 + PbI2∙ 2DMSO + PbI2∙ DMSO +
20MAI
>30–65 °C 2(MA)2(DMSO)2Pb3I8 + 2PbI2∙ DMSO + 20MAI
70–75 °C 2(MA)2(DMSO)2Pb3I8 + PbI2∙ DMSO + MAPbI3 + 19MAI
80–140 °C (MA)2(DMSO)2Pb3I8 + PbI2∙ DMSO + 3MAPbI3 +
(MA)2(DMSO)xPbI4 + 17MAI
>140–160 °C 3(MA)2(DMSO)xPbI4 + 5MAPbI3 + 13MAI
>165–185 °C 0.5(MA)2(DMSO)2Pb3I8 + 0.5(MA)2(DMSO)xPbI4 +
6MAPbI3 + 16MAI
>185–200 °C PbI2∙ DMSO + 7MAPbI3 + 17MAI
205 °C 8MAPbI3 + 16MAI
8PbI2 + 24MAI 20–30 °C 2(MA)2(DMSO)2Pb3I8 + PbI2∙ 2DMSO + PbI2∙ DMSO +
20MAI
PbI2∙ 2DMSO + PbI2∙
DMSO
>30–65 °C 2PbI2∙ DMSO + DMSO
2PbI2∙ DMSO + MAI 70–75 °C PbI2∙ DMSO + MAPbI3 + DMSO
2(MA)2(DMSO)2Pb3I8 +
2MAI
80–140 °C (MA)2(DMSO)2Pb3I8 + 2MAPbI3 + (2-x)DMSO +
(MA)2(DMSO)xPbI4
(MA)2(DMSO)2Pb3I8 +
3MAI >140–165 °C
MAPbI3 + 2(MA)2(DMSO)xPbI4 + (2-2x) DMSO
PbI2∙ DMSO + MAI MAPbI3 + DMSO
3(MA)2(DMSO)xPbI4 >165-185 °C 0.5(MA)2(DMSO)2Pb3I8 + MAPbI3 + 3MAI +
0.5(MA)2(DMSO)xPbI4 + (2.5x-1) DMSO
0.5(MA)2(DMSO)2Pb3I8
+ 0.5(MA)2(DMSO)
xPbI4
>185-200 °C PbI2∙ DMSO + MAPbI3 + MAI + 0.5xDMSO
PbI2∙ DMSO + MAI 205 °C MAPbI3 + DMSO
88 ISSN 2708-129X. Укр. хім. журн., 2022
INFLUENCE OF THE SOLVENT AND THE RATIO OF STARTING REAGENTS ON THE PROPERTIES
OF ORGANIC-INORGANIC PEROVSKITE MAPbI3INORGANIC CHEMISTRY
Thus, regardless of the ratio of starting re-
agents in DMSO, the formation of MAPbI3
perovskite occurs through the formation of 4
intermediate compounds. When the ratio of
reagents increases, the temperature of forma-
tion of single-phase MAPbI3 film increases.
Crystallographic and electrophysical charac-
teristics of organic-inorganic perovskites MAPbI3,
obtained at different ratios PbI2:MAI in DMF,
and DMSO. The calculation of the unit cell
parameters of organic-inorganic MAPbI3 pe
rovskite films was performed by the Rietveld
full-profile analysis method using X-ray dif-
fraction patterns (Fig. 3).
Fig. 3. Experimental X-ray diffraction patterns of samples of MAPbI3 films obtained at different
ratios of starting reagents in the DMSO solvent. The Miller indices are given in parentheses. * –
(MA)2(DMSO)2Pb3I8.
9
Reagents Temperature Reaction products
0,5(MA)2(DMSO)xPbI4 + (2,5x-1) DMSO
0,5(MA)2(DMSO)2Pb3I8 +
0,5(MA)2(DMSO)xPbI4
>185-200 °C PbI2∙ DMSO + MAPbI3 + MAI + 0,5xDMSO
PbI2∙ DMSO + MAI 205 °C MAPbI3 + DMSO
Thus, regardless of the ratio of starting reagents in DMSO, the formation of MAPbI3 perovskite occurs
through the formation of 4 intermediate compounds. When the ratio of reagents increases, the temperature of
formation of single-phase MAPbI3 film increases.
Crystallographic and electrophysical characteristics of organic-inorganic perovskites MAPbI3,
obtained at different ratios PbI2:MAI in DMF, and DMSO. The calculation of the unit cell parameters of
organic-inorganic MAPbI3 perovskite films was performed by the Rietveld full-profile analysis method using
X-ray diffraction patterns (Fig. 3).
Fig. 3. Experimental X-ray diffraction patterns of samples of MAPbI3 films obtained at different ratios of starting
reagents in the DMSO solvent. The Miller indices are given in parentheses. * – (MA)2(DMSO)2Pb3I8.
It was found that depending on the ratio of starting reagents and solvent, there are slight changes in
the volume of the cell for perovskite films (Table 7). The changes in the unit cell volume are associated with
a small amount of the solvent that is part of the crystalline structure of perovskite. It was proved that the
solvent DMSO can replace the cation MA+ in the structure of organic-inorganic perovskite MAPbI3 [17]. The
radius of DMSO and DMF molecules are 3.05 Å and 3.13 Å, respectively [18], and the radius of the cation
MA+ is 2.17 Å [19]. Since DMF and DMSO molecules are close in size, it can be assumed that DMF enters
into the crystal structure, creating deformations. To test this assumption, we will calculate the changes in
volume and solvent concentration.
From literature, it is known that the volume of the unit cell for perovskite is Vperovskite = 990 Å3 [20], or
Vperovskite/Z = 990/4 = 247.5 Å3. Table 7 shows that the experimental values of unit cell volume are slightly
larger than the theoretical value of unit cell volume of 990 Å3.
Table 7
Structural parameters of organic-inorganic perovskites MAPbI3, obtained at different ratios
PbI2:MAI (1:1, 1:2, 1:3) in the DMF and DMSO solvents.
Parameters DMF DMSO
1:1 1:2 1:3 1:1 1:2 1:3
V, Å3 994.5(3) 998.6(5) 997.5(4) 991.3(1) 994.7(4) 994.5(2)
Deposition
temperature
115 °С 170 °С 175 °С 150 °С 190 °С 205 °С
It was found that depending on the ratio
of starting reagents and solvent, there are
slight changes in the volume of the cell for
perovskite films (Table 7). The changes in the
unit cell volume are associated with a small
amount of the solvent that is part of the crys-
talline structure of perovskite. It was proved
that the solvent DMSO can replace the cati-
on MA+ in the structure of organic-inorganic
perovskite MAPbI3 [15]. The radius of DMSO
and DMF molecules are 3.05 Å and 3.13 Å,
respectively [16], and the radius of the cation
MA+ is 2.17 Å [17]. Since DMF and DMSO
molecules are close in size, it can be assumed
that DMF enters into the crystal structure,
creating deformations. To test this assump-
tion, we will calculate the changes in volume
and solvent concentration.
From literature, it is known that the volu
me of the unit cell for perovskite is Vperovskite =
990 Å3
[18], or Vperovskite/Z = 990/4 = 247.5 Å3.
Table 7 shows that the experimental values of
unit cell volume are slightly larger than the
theoretical value of unit cell volume of 990 Å3.
89https://ucj.org.ua
Torchyniuk P.V., V’yunov O.I., Vlasyuk V.M., Kostylyov V. P., Belous A.G. UCJ № 4 / Vol. 88
Table 7
Structural parameters of organic-inorganic perovskites MAPbI3, obtained at different
ratios PbI2:MAI (1:1, 1:2, 1:3) in the DMF and DMSO solvents.
Parameters
DMF DMSO
1:1 1:2 1:3 1:1 1:2 1:3
V, Å3 994.5(3) 998.6(5) 997.5(4) 991.3(1) 994.7(4) 994.5(2)
Deposition
temperature 115 °С 170 °С 175 °С 150 °С 190 °С 205 °С
The calculation of the amount of solvent in
the structure of perovskite was performed ac-
cording to formula (1) using the unit cell vo
lumes of the starting reagents, and perovskite,
as well as the volumes of DMF, DMSO solvent
molecules, and methylammonium cation MA+:
where Z1, Z2, and Z3 are the formula unit for
perovskite, PbI2, and MAI, respectively, x is the
amount of solvent included in the structure of
perovskite, V(PbI2) is the unit cell volume of
PbI2, V(MAI) is the unit cell volume of MAI,
Vsolvent is the volume of the solvent molecule,
V (MA+) is the volume of the methylammoni-
um cation MA+. Taking into account the values
of the volumes of compounds and their for-
mula units, we obtain V(PbI2)/Z2 = 125.69/1 =
125.69 Å3, V(MAI)/Z3 = 235.93/2 = 117.965 Å3,
The calculation of the volume of the solvent
(Vsolvent) was performed according to formula
(2) under the assumption that the solvent mo
lecule has a spherical shape [18].
, (2)
where R is the radius of the solvent molecule.
A similar volume calculation was performed
for the MA+ cation. The volume of the DMF
and DMSO solvents is V(DMF) = 128.4 Å3, and
V(DMSO) = 118.8 Å3, respectively. The volume of
the cation MA+ is V (MA+) = 42.8 Å3.
The replacement of a smaller MA+ cation
with a larger molecule of DMF or DMSO leads
to minor changes in structural and electro-
physical characteristics, which is confirmed by
the following calculations.
The solvent content of the structure (x) was
determined from formula (3), which was de-
rived from formula (1):
. (3)
The results of the calculations are summa-
rized in table 8.
10
The calculation of the amount of solvent in the structure of perovskite was performed according to
formula (1) using the unit cell volumes of the starting reagents, and perovskite, as well as the volumes of
DMF, DMSO solvent molecules, and methylammonium cation MA+:
𝑉𝑉𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝
𝑍𝑍1
= 𝑉𝑉(𝑃𝑃𝑃𝑃𝐼𝐼2)
𝑍𝑍2
+ 𝑉𝑉(𝑀𝑀𝑀𝑀𝑀𝑀)
𝑍𝑍3
+ (𝑉𝑉𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠 − 𝑉𝑉(𝑀𝑀𝑀𝑀+)) ∙ 𝑥𝑥 , (1)
where Z1, Z2, and Z3 are the formula unit for perovskite, PbI2, and MAI, respectively, x is the amount of
solvent included in the structure of perovskite, V(PbI2) is the unit cell volume of PbI2, V(MAI) is the unit cell
volume of MAI, Vsolvent is the volume of the solvent molecule, V (MA+) is the volume of the
methylammonium cation MA+. Taking into account the values of the volumes of compounds and their
formula units, we obtain V(PbI2)/Z2 = 125.69/1 = 125.69 Å3, V(MAI)/Z3 = 235.93/2 = 117.965 Å3,
The calculation of the volume of the solvent (Vsolvent) was performed according to formula (2) under
the assumption that the solvent molecule has a spherical shape [Ошибка! Источник ссылки не найден.].
𝑉𝑉 = 4
3 𝜋𝜋𝑅𝑅3 (2),
where R is the radius of the solvent molecule. A similar volume calculation was performed for the MA+
cation. The volume of the DMF and DMSO solvents is V(DMF) = 128.4 Å3, and V(DMSO) = 118.8 Å3,
respectively. The volume of the cation MA+ is V (MA+) = 42.8 Å3.
The replacement of a smaller MA+ cation with a larger molecule of DMF or DMSO leads to minor
changes in structural and electrophysical characteristics, which is confirmed by the following calculations.
The solvent content of the structure (x) was determined from formula (3), which was derived from
formula (1):
x =
Vperovskite
Z1
−
V(PbI2)
Z2
−
V(MAI)
Z3
Vsolvent−V(MA+)
(3)
The results of the calculations are summarized in table 8.
Table 8
Determination of the amount of solvent in the structure of perovskite depending on the ratios of starting
reagents PbI2:MAI in the DMF, DMSO solvent.
PbI2:MAI Vperovskite, Å3 Z1 Vperovskite/Z1, Å3 Vsolvent, Å3 x, %
MAPbI3 990.0 4 247,5 – – 0
1:1 991.3(1) 4 247,8
DMSO
118,8
5.5
1:2 994.7(4) 4 248,7 6.6
1:3 994.5(2) 4 248,6 6.5
1:1 994.5(3) 4 248,6
DMF
128,4
5.8
1:2 998.6(5) 4 249,6 7.0
1:3 997.5(4) 4 249,4 6.7
It was found that at the same ratios of starting reagents, the structure of perovskite included the DMF
solvent in a greater amount than DMSO.
The fact that the solvent is part of the structure of perovskite affects not only the structural parameters
but also the electrophysical characteristics, in particular, the width of the bandgap (Table 9).
Table 9
Influence of the solvent on the electrophysical characteristics of perovskite MAPbI3.
Solvent DMF DMSO
PbI2:MAI 1:1 1:2 1:3 1:1 1:2 1:3
Solvent content, % 0 5.8 7 6.7 5.5 6.6 6.5
Bandgap, еV 1.55 [20] 1.59 1.62 1.57 1.57 1.53 1.54
(1)
10
The calculation of the amount of solvent in the structure of perovskite was performed according to
formula (1) using the unit cell volumes of the starting reagents, and perovskite, as well as the volumes of
DMF, DMSO solvent molecules, and methylammonium cation MA+:
𝑉𝑉𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝
𝑍𝑍1
= 𝑉𝑉(𝑃𝑃𝑃𝑃𝐼𝐼2)
𝑍𝑍2
+ 𝑉𝑉(𝑀𝑀𝑀𝑀𝑀𝑀)
𝑍𝑍3
+ (𝑉𝑉𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠 − 𝑉𝑉(𝑀𝑀𝑀𝑀+)) ∙ 𝑥𝑥 , (1)
where Z1, Z2, and Z3 are the formula unit for perovskite, PbI2, and MAI, respectively, x is the amount of
solvent included in the structure of perovskite, V(PbI2) is the unit cell volume of PbI2, V(MAI) is the unit cell
volume of MAI, Vsolvent is the volume of the solvent molecule, V (MA+) is the volume of the
methylammonium cation MA+. Taking into account the values of the volumes of compounds and their
formula units, we obtain V(PbI2)/Z2 = 125.69/1 = 125.69 Å3, V(MAI)/Z3 = 235.93/2 = 117.965 Å3,
The calculation of the volume of the solvent (Vsolvent) was performed according to formula (2) under
the assumption that the solvent molecule has a spherical shape [Ошибка! Источник ссылки не найден.].
𝑉𝑉 = 4
3 𝜋𝜋𝑅𝑅3 (2),
where R is the radius of the solvent molecule. A similar volume calculation was performed for the MA+
cation. The volume of the DMF and DMSO solvents is V(DMF) = 128.4 Å3, and V(DMSO) = 118.8 Å3,
respectively. The volume of the cation MA+ is V (MA+) = 42.8 Å3.
The replacement of a smaller MA+ cation with a larger molecule of DMF or DMSO leads to minor
changes in structural and electrophysical characteristics, which is confirmed by the following calculations.
The solvent content of the structure (x) was determined from formula (3), which was derived from
formula (1):
x =
Vperovskite
Z1
−
V(PbI2)
Z2
−
V(MAI)
Z3
Vsolvent−V(MA+)
(3)
The results of the calculations are summarized in table 8.
Table 8
Determination of the amount of solvent in the structure of perovskite depending on the ratios of starting
reagents PbI2:MAI in the DMF, DMSO solvent.
PbI2:MAI Vperovskite, Å3 Z1 Vperovskite/Z1, Å3 Vsolvent, Å3 x, %
MAPbI3 990.0 4 247,5 – – 0
1:1 991.3(1) 4 247,8
DMSO
118,8
5.5
1:2 994.7(4) 4 248,7 6.6
1:3 994.5(2) 4 248,6 6.5
1:1 994.5(3) 4 248,6
DMF
128,4
5.8
1:2 998.6(5) 4 249,6 7.0
1:3 997.5(4) 4 249,4 6.7
It was found that at the same ratios of starting reagents, the structure of perovskite included the DMF
solvent in a greater amount than DMSO.
The fact that the solvent is part of the structure of perovskite affects not only the structural parameters
but also the electrophysical characteristics, in particular, the width of the bandgap (Table 9).
Table 9
Influence of the solvent on the electrophysical characteristics of perovskite MAPbI3.
Solvent DMF DMSO
PbI2:MAI 1:1 1:2 1:3 1:1 1:2 1:3
Solvent content, % 0 5.8 7 6.7 5.5 6.6 6.5
Bandgap, еV 1.55 [20] 1.59 1.62 1.57 1.57 1.53 1.54
10
The calculation of the amount of solvent in the structure of perovskite was performed according to
formula (1) using the unit cell volumes of the starting reagents, and perovskite, as well as the volumes of
DMF, DMSO solvent molecules, and methylammonium cation MA+:
𝑉𝑉𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝
𝑍𝑍1
= 𝑉𝑉(𝑃𝑃𝑃𝑃𝐼𝐼2)
𝑍𝑍2
+ 𝑉𝑉(𝑀𝑀𝑀𝑀𝑀𝑀)
𝑍𝑍3
+ (𝑉𝑉𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠 − 𝑉𝑉(𝑀𝑀𝑀𝑀+)) ∙ 𝑥𝑥 , (1)
where Z1, Z2, and Z3 are the formula unit for perovskite, PbI2, and MAI, respectively, x is the amount of
solvent included in the structure of perovskite, V(PbI2) is the unit cell volume of PbI2, V(MAI) is the unit cell
volume of MAI, Vsolvent is the volume of the solvent molecule, V (MA+) is the volume of the
methylammonium cation MA+. Taking into account the values of the volumes of compounds and their
formula units, we obtain V(PbI2)/Z2 = 125.69/1 = 125.69 Å3, V(MAI)/Z3 = 235.93/2 = 117.965 Å3,
The calculation of the volume of the solvent (Vsolvent) was performed according to formula (2) under
the assumption that the solvent molecule has a spherical shape [Ошибка! Источник ссылки не найден.].
𝑉𝑉 = 4
3 𝜋𝜋𝑅𝑅3 (2),
where R is the radius of the solvent molecule. A similar volume calculation was performed for the MA+
cation. The volume of the DMF and DMSO solvents is V(DMF) = 128.4 Å3, and V(DMSO) = 118.8 Å3,
respectively. The volume of the cation MA+ is V (MA+) = 42.8 Å3.
The replacement of a smaller MA+ cation with a larger molecule of DMF or DMSO leads to minor
changes in structural and electrophysical characteristics, which is confirmed by the following calculations.
The solvent content of the structure (x) was determined from formula (3), which was derived from
formula (1):
x =
Vperovskite
Z1
−
V(PbI2)
Z2
−
V(MAI)
Z3
Vsolvent−V(MA+)
(3)
The results of the calculations are summarized in table 8.
Table 8
Determination of the amount of solvent in the structure of perovskite depending on the ratios of starting
reagents PbI2:MAI in the DMF, DMSO solvent.
PbI2:MAI Vperovskite, Å3 Z1 Vperovskite/Z1, Å3 Vsolvent, Å3 x, %
MAPbI3 990.0 4 247,5 – – 0
1:1 991.3(1) 4 247,8
DMSO
118,8
5.5
1:2 994.7(4) 4 248,7 6.6
1:3 994.5(2) 4 248,6 6.5
1:1 994.5(3) 4 248,6
DMF
128,4
5.8
1:2 998.6(5) 4 249,6 7.0
1:3 997.5(4) 4 249,4 6.7
It was found that at the same ratios of starting reagents, the structure of perovskite included the DMF
solvent in a greater amount than DMSO.
The fact that the solvent is part of the structure of perovskite affects not only the structural parameters
but also the electrophysical characteristics, in particular, the width of the bandgap (Table 9).
Table 9
Influence of the solvent on the electrophysical characteristics of perovskite MAPbI3.
Solvent DMF DMSO
PbI2:MAI 1:1 1:2 1:3 1:1 1:2 1:3
Solvent content, % 0 5.8 7 6.7 5.5 6.6 6.5
Bandgap, еV 1.55 [20] 1.59 1.62 1.57 1.57 1.53 1.54
90 ISSN 2708-129X. Укр. хім. журн., 2022
INFLUENCE OF THE SOLVENT AND THE RATIO OF STARTING REAGENTS ON THE PROPERTIES
OF ORGANIC-INORGANIC PEROVSKITE MAPbI3INORGANIC CHEMISTRY
Table 8
Determination of the amount of solvent in the structure of perovskite depending on the
ratios of starting reagents PbI2:MAI in the DMF, DMSO solvent.
PbI2:MAI Vperovskite. Å
3 Z1 Vperovskite/Z1. Å
3 Vsolvent. Å
3 x. %
MAPbI3 990.0 4 247.5 – – 0
1:1 991.3(1) 4 247.8
DMSO 118.8
5.5
1:2 994.7(4) 4 248.7 6.6
1:3 994.5(2) 4 248.6 6.5
1:1 994.5(3) 4 248.6
DMF 128.4
5.8
1:2 998.6(5) 4 249.6 7.0
1:3 997.5(4) 4 249.4 6.7
It was found that at the same ratios of start-
ing reagents, the structure of perovskite in-
cluded the DMF solvent in a greater amount
than DMSO.
The fact that the solvent is part of the struc-
ture of perovskite affects not only the struc-
tural parameters but also the electrophysical
characteristics, in particular, the width of the
bandgap (Table 9).
Table 9
Influence of the solvent on the electrophysical characteristics of perovskite MAPbI3.
Solvent DMF DMSO
PbI2:MAI 1:1 1:2 1:3 1:1 1:2 1:3
Solvent content, % 0 5.8 7 6.7 5.5 6.6 6.5
Bandgap, еV 1.55 [18] 1.59 1.62 1.57 1.57 1.53 1.54
The bandgap for the perovskites obtained at
different ratios of starting reagents in DMSO
is less than for the films obtained using DMF.
CONCLUSIONS
The peculiarities of formation and proper-
ties of organic-inorganic MAPbI3 perovskite
films have been studied as a function of the
ratio of starting reagents in DMF and DMSO
solvents. As the PbI2:MAI ratio increases, the
temperature of the formation of single-phase
MAPbI3 perovskite film increases. It was found
that when using the DMF solvent, the number
of crystalline phases in the film depends on
91https://ucj.org.ua
Torchyniuk P.V., V’yunov O.I., Vlasyuk V.M., Kostylyov V. P., Belous A.G. UCJ № 4 / Vol. 88
the ratio of starting reagents. At a ratio of 1:1
in DMF, the number of phases is 4 and at 1:2,
1:3 5, and 3, respectively. When using DMSO,
regardless of the ratio of starting reagents,
there are 5 crystalline phases in the film.
Plots of the percentage of crystalline phases
in the film versus the treatment temperature
have been constructed for perovskite films
synthesized at different ratios of starting rea-
gents in the DMF, and DMSO solvents. It was
shown that the formation of organic-inorganic
perovskite occurs through the formation and
decomposition of intermediate compounds
(phases). Reactions of MAPbI3 perovskite for-
mation at different ratios PbI2:MAI in DMF
and DMSO have been obtained.
It was found that for the perovskite films
obtained at different ratios PbI2: MAI in DMF
and DMSO, there are slight changes in the
structural (unit cell volume) and electrophy
sical (bandgap) characteristics. These changes
are related to the solvent that is included in the
crystalline structure of perovskite. It was found
that at the same ratios of starting reagents,
DMF is included in the structure of perovskite
in a greater amount than DMSO.
Acknowledgment. The authors ex-
press their gratitude to the Armed
Forces of Ukraine for providing secu-
rity to perform this work. This work
has become possible only because
of the fortitude and courage of the
Ukrainian Army.
ВПЛИВ РОЗЧИННИКА ТА СПІВВІДНОШЕННЯ
ВИХІДНИХ РЕАГЕНТІВ НА ВЛАСТИВОСТІ ОР
ГАНО-НЕОРГАНІЧНОГО ПЕРОВСЬКІТУ MAPbI3
Торчинюк П. В.1, В’юнов О. І.1,
Власюк В. М. 2, Костильов В. П. 2,
Білоус А. Г.1
1Інститут загальної та неорганічної хімії
ім. В. І. Вернадського НАН України, просп.
Академіка Палладіна, 32/34, Київ, 03142,
Україна
2Інститут фізики напівпровідників імені
В. Є. Лашкарьова НАН України, просп. На
уки, 41, Київ, 03028, Україна
* e-mail: vyunov@ionc.kiev.ua
Синтезовано органо-неорганічний пе-
ровськіт MAPbI3 (CH3NH3PbI3) методом
одностадійного осадження за різного спів-
відношення вихідних реагентів (PbI2 та
MAI, які брали у співвідношенні 1:1, 1:2,
1:3) у розчиннику ДМФА та ДМСО. Для от-
римання плівок органо-неорганічного пе-
ровськіту MAPbI3 використовували метод
spin-coating.
Досліджено особливості утворення та
властивості плівок органо-неорганічного
перовськіту MAPbI3 залежно від співвід-
ношення вихідних реагентів у розчиннику
DMF, DMSO. Зі збільшенням співвідношен-
ня PbI2:MAI зростає температура утворен-
ня однофазної плівки перовськіту MAPbI3.
Показано, що утворення органо-неорганіч-
ного перовськіту відбувається через утво-
рення та розкладання проміжних сполук
(фаз). Отримано реакції утворення перов-
ськіту MAPbI3 за різного співвідношення
PbI2:MAI у DMF, DMSO.
92 ISSN 2708-129X. Укр. хім. журн., 2022
INFLUENCE OF THE SOLVENT AND THE RATIO OF STARTING REAGENTS ON THE PROPERTIES
OF ORGANIC-INORGANIC PEROVSKITE MAPbI3INORGANIC CHEMISTRY
Встановлено, що структура перовськіту
MAPbI3 починає формуватися за темпера-
тури 20–25 °C незалежно від співвідношен-
ня вихідних реагентів у DMF. При викорис-
танні DMSO структура перовськіту MAPbI3
починає формуватися за температури 60 °C
для співвідношень 1:1, 1:2, та при 70 °C для
співвідношення 1:3.
Встановлено, що при використанні роз-
чинника DMF кількість кристалічних фаз
у плівці залежить від співвідношення ви-
хідних реагентів. При співвідношенні 1:1 у
DMF кількість фаз становить 4, а при 1:2,
1:3 – 5 та 3 відповідно. При використанні
DMSO незалежно від співвідношення ви-
хідних реагентів у плівці присутні 5 криста-
лічних фаз.
Для плівок перовськіту, отриманих за
різного співвідношення вихідних реагентів
у розчиннику DMF, DMSO, було побудова-
но залежність вмісту кристалічних фаз у
плівці від температури оброблення. Вста-
новлено, що для плівок перовськіту, отри-
маних за різного співвідношення PbI2:MAI
у DMF, DMSO спостерігаємо незначні змі-
ни в структурних (об’єм елементарної ко-
мірки) та електрофізичних (ширина забо-
роненої зони) характеристиках. Ці зміни
пов’язані з розчинником, який входить у
кристалічну структуру перовськіту. Вста-
новлено, що за однакових співвідношень
вихідних реагентів DMF входить в струк-
туру перовськіту у більшій кількості, ніж
DMSO.
Ключові слова: органо-неорганічний
перовськіт, фазові перетворення, струк-
турні параметри, електрофізичні характе-
ристики.
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Стаття надійшла 18.05.2022.
|
| id | oai:ojs2.1444248.nisspano.web.hosting-test.net:article-434 |
| institution | Ukrainian Chemistry Journal |
| keywords_txt_mv | keywords |
| language | English |
| last_indexed | 2026-07-23T01:08:07Z |
| publishDate | 2022 |
| publisher | V.I.Vernadsky Institute of General and Inorganic Chemistry |
| record_format | ojs |
| resource_txt_mv | ucjorgua/3b/171ef8dce68a88cfede15bed316f073b.pdf |
| spelling | oai:ojs2.1444248.nisspano.web.hosting-test.net:article-4342026-07-22T08:23:49Z INFLUENCE OF THE SOLVENT AND THE RATIO OF STARTING REAGENTS ON THE PROPERTIES OF ORGANIC-INORGANIC PEROVSKITE MAPbI3 Torchyniuk, Pavlo V'yunov, Oleg Vlasyuk, Viktor Kostylyov, Vitaliy Belous, Anatolii organic-inorganic perovskite, phase transformations, structural parameters, electrophysical characteristics. The peculiarities of formation and properties of organiс-inorganic MAPbI3 perovskite films, obtained from solutions with different ratios of starting reagents (PbI2:MAI = 1:1,1:2, and 1:3), in the DMF and DMSO solvents, studied. As the PbI2:MAI ratio increases, the temperature of the formation of a single-phase MAPbI3 perovskite film also increases. The slight changes in the structural and electrophysical characteristics for perovskite films obtained at the  different ratios of PbI2:MAI in DMF and DMSO were found. These changes are related to the solvent that is included in the crystalline structure of perovskite. In the same ratios of starting reagents, DMF is included in the structure of perovskite in a greater amount than DMSO. V.I.Vernadsky Institute of General and Inorganic Chemistry 2022-05-25 Article Article Inorganic Chemistry Неорганическая химия Неорганічна хімія application/pdf https://ucj.org.ua/index.php/journal/article/view/434 10.33609/2708-129X.88.04.2022.79-93 Ukrainian Chemistry Journal; Vol. 88 No. 4 (2022): Ukrainian Chemistry Journal; 79-93 Украинский химический журнал; ##issue.vol## 88 ##issue.no## 4 (2022): Ukrainian Chemistry Journal; 79-93 Український хімічний журнал; Том 88 № 4 (2022): Український хімічний журнал; 79-93 2708-129X 2708-1281 en https://ucj.org.ua/index.php/journal/article/view/434/222 Copyright (c) 2022 Pavlo Torchyniuk, Oleg V'yunov, Viktor Vlasyuk, Vitaliy Kostylyov, Anatolii Belous https://creativecommons.org/licenses/by-nc/4.0 |
| spellingShingle | Torchyniuk, Pavlo V'yunov, Oleg Vlasyuk, Viktor Kostylyov, Vitaliy Belous, Anatolii INFLUENCE OF THE SOLVENT AND THE RATIO OF STARTING REAGENTS ON THE PROPERTIES OF ORGANIC-INORGANIC PEROVSKITE MAPbI3 |
| title | INFLUENCE OF THE SOLVENT AND THE RATIO OF STARTING REAGENTS ON THE PROPERTIES OF ORGANIC-INORGANIC PEROVSKITE MAPbI3 |
| title_full | INFLUENCE OF THE SOLVENT AND THE RATIO OF STARTING REAGENTS ON THE PROPERTIES OF ORGANIC-INORGANIC PEROVSKITE MAPbI3 |
| title_fullStr | INFLUENCE OF THE SOLVENT AND THE RATIO OF STARTING REAGENTS ON THE PROPERTIES OF ORGANIC-INORGANIC PEROVSKITE MAPbI3 |
| title_full_unstemmed | INFLUENCE OF THE SOLVENT AND THE RATIO OF STARTING REAGENTS ON THE PROPERTIES OF ORGANIC-INORGANIC PEROVSKITE MAPbI3 |
| title_short | INFLUENCE OF THE SOLVENT AND THE RATIO OF STARTING REAGENTS ON THE PROPERTIES OF ORGANIC-INORGANIC PEROVSKITE MAPbI3 |
| title_sort | influence of the solvent and the ratio of starting reagents on the properties of organic-inorganic perovskite mapbi3 |
| topic_facet | organic-inorganic perovskite phase transformations structural parameters electrophysical characteristics. |
| url | https://ucj.org.ua/index.php/journal/article/view/434 |
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