Supporting information Low-Temperature Synthesis of Bismuth Chalcohalides: Candidate Photovoltaic Materials with Easily, Continuously Controllable Band gap Hironobu Kunioku1, Masanobu Higashi1, Ryu Abe1,2,* 1
Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University Katsura, Nishikyo-ku, Kyoto 615-8510, Japan 2
CREST, Japan Science and Technology Agency (JST), Kawaguchi, Saitama 332-0012, Japan *
[email protected]
Si
● Bi12.7S18I2 (PDF 01-073-1157)
●
Intensity / a. u.
●
● ●
● ●
●● ● ● ● ●● ●●
● ●●
●
400 °C
● ●
●● ●● ● ●● ● ● ● ●
●
300 °C
●
200 °C 150 °C BiSI (PDF 00-043-0652)
10
20
30 40 2θ / degree (Cu Kα)
50
60
Figure S1. XRD patterns of the prepared samples at high temperature.
Table S1. Atomic % of BiOI before and after H2S treatment as determined by EDX analysis. Atomic % Before
After
Bi
34
34
O
33
n.d.
S
n.d.
32
I
33
33
BiSI (PDF 00-043-0652)
Intensity / a. u.
(d) 60 min (c) 30 min (b) 15 min (a) Before BiOI (PDF 00-010-0445)
10
20
30
40
50
60
2θ / degree (Cu Kα)
Figure S2. XRD patterns of prepared samples (a) before and after the heat treatment with 5% H2S gas at 150 °C for (b) 15 min, (c) 30 min, and (d) 60 min.
Figure S3. SEM images of prepared BiOI and BiSI (after heating under H2S flow at 150 °C).
BiSeI (PDF 00-044-0162)
Intensity / a. u.
After H2Se treatment
Before
BiOI (PDF 00-010-0445)
10
20
30
40
50
60
2θ / degree (Cu Kα)
Figure S4. XRD patterns of prepared BiSBr1–xIx samples by heat treatment with H2Se gas.
Kubelka−Munk / a. u.
3
BiSeI 2
1
BiSI 0 400
500
600
700
800
900
1000
Wavelength / nm
Figure S5. UV–vis diffuse reflectance spectra of BiSI and BiSeI.
Figure S6. Crystal structure of BiOX (X = Cl, Br, I).
8.6
10.4
8.5
b-axis /Å b-axis/Å
a-axis /Å a-axis/Å
10.2 8.4 8.3 8.2
10.0
9.8 8.1 8.0
9.6 0.0
0.2
0.4
0.6
0.8
1.0
I− content x for x BiSBr1−xIx
0.0
0.2
0.4
0.6
0.8
I− content xxfor BiSBr1−xIx
4.20
c-axis /Å c-axis/Å
4.15
4.10
4.05
4.00 0.0
0.2
I−
0.4
0.6
0.8
1.0
content x for x BiSBr1−xIx
Figure S7. Lattice constants of BiSBr1–xIx calculated by Le Bail analysis.
1.0
I/(Br+I)
1.0
BiOBr1−xIx ● BiSBr1−xIx
EDX EDX Atomic atomic Ratios ratio
▲
0.8 0.6 0.4 0.2 0.0 0.0
0.2
I−
0.4
0.6
0.8
1.0
content x for BiOBr I or BiSBr1−xIx x 1−x x
Figure S8. Atomic ratio of I to (Br+I) determined by the EDX analysis of BiOBr1–xIx and BiSBr1–xIx.
2.8
! BiOBr1−xIx ! BiSBr1−xIx
Indirect Band Indirect band Gap gap // eV eV
2.6 2.4 2.2 2.0 1.8 1.6 1.4 0.0
0.2
I−
0.4
0.6
0.8
1.0
content x for BiOBr x 1−xIx or BiSBr1−xIx
Figure S9. Indirect band gap of BiOBr1–xIx and BiSBr1–xIx.
40
25
b) BiSI
Total Bi (Total) S (Total) Br (Total)
30
DOS(Electrons (Electrons/ /eV) eV) DOS
DOS (Electrons DOS (Electrons //eV) eV)
a) BiSBr
20
10
Total Bi (Total) S (Total) I (Total)
20
15
10
5
0
0 -4
-2
0
2
4
6
-4
-2
Energy / eV Energy
0 2 Energy Energy/ /eV eV
4
6
Figure S10. Density of states (DOS) of a) BiSBr and b) BiSI, and PDOS projected onto each constituent element.
14 DOS (Electrons / eV)
12
a) BiOBr
Total Bi (Total) O (Total) Br (Total)
12 10 8 6 4
b) BiOI
Total Bi (Total) O (Total) I (Total)
10 DOS (Electrons / eV)
16
8 6 4 2
2
0
0 -6
-4
-2
0
2
Energy / eV
4
6
-6
-4
-2
0
2
4
6
Energy / eV
Figure S11. Density of states (DOS) of a) BiOBr and b) BiOI and, PDOS projected onto each constituent element.
SnO2
BiSI (PDF 00-043-0652)
Intensity / a. u.
After H2S treatment
BiOI-cated FTO (via squeegee)
BiOI (PDF 00-010-0445) 10
20
30
40
50
60
2θ / degree (Cu Kα)
Figure S12. XRD patterns of the BiSI electrode prepared via the squeegee method using BiOI particles, which involves heating the BiOI-coated FTO under H2S/Ar at 150 °C.
SnO2
BiSI (PDF 00-043-0652)
Intensity / a. u.
After H2S treatment
BiOI-cated FTO (via EPD)
BiOI (PDF 00-010-0445) 10
20
30
40
50
60
2θ / degree (Cu Kα)
Figure S13. XRD patterns of the BiSI electrode prepared by heating the BiOI-coated FTO via the EPD of BiOI particles under H2S/Ar at 150 °C.
BiOI (PDF 00-010-0445)
001
x = 1.0
Intensity
Intensity / a. u.
x = 0.8 x = 0.6 x = 0.4 x = 0.2 x=0 BiOBr (PDF
10
20
30
40
50
)
001
60 9
10
2θ / degree (Cu Kα) 2θ/degree
11
12
2θ / degree (Cu Kα) 2θ/degree
Figure S14. XRD patterns of prepared BiOBr1–xIx.
4.00
a/Å / Å a-axis
3.98
3.96
3.94
3.92
3.90 0.0
0.2
I−
0.4
0.6
0.8
1.0
content x xfor BiOBr1−xIx
Figure S15. Lattice parameter of BiOBr1–xIx calculated by Le Bail analysis.
