Supporting Information Shape-controlled Synthesis of All-inorganic ...
Supporting Information
Shape-controlled Synthesis of All-inorganic CsPbBr3 Perovskite Nanocrystals with Bright Blue Emission Zhiqin Liang1,2 , Suling Zhao1,2, *, Zheng Xu1,2, Bo qiao1,2 , Pengjie Song1,2 , Di Gao1,2 , Xurong Xu1,2
1
Key Laboratory of Luminescence and Optical Information, Beijing Jiaotong
University, Ministry of Education, Beijing, 100044, China 2
Institute of Optoelectronics Technology, Beijing Jiaotong University, Beijing,
100044, China
*
Corresponding author: [email protected]
S-1
Figure S1. (a) TEM image of colloidal CsPbBr3 quantum dots. (b) Size distribution histogram for the samples shown in (a).
Figure S2. EDX spectra of the CsPbBr3 single quantum dots.
S-2
Figure S3. (a) Low-resolution TEM image depicting close-ups of CsPbBr3 lamellar structures. (b and c) Magnified TEM images in (a).
From the magnified TEM images in Figure S3 (b) and (c), we can obviously observe the CsPbBr3 quantum dots grow and align along with the organic mesostructures, thus forming the CsPbBr3 lamellar structures. We infer this phenomenon is related to the organic mesostructures that serve as a soft template.
S-3
Figure S4. Size distribution histogram for the samples shown in Figure S3b.
Figure S5. EDX spectra of the CsPbBr3 lamellar-structured quantum dots.
S-4
Figure S6. Size distribution histogram for the CsPbBr3 nanoplatelets stacking face-to-face.
Figure S7. EDX spectra of the CsPbBr3 nanoplatelets stacked face-to-face.
S-5
Figure S8. EDX spectra of the 2D CsPbBr3 nanosheets.
EDX indicates that these CsPbBr3 nanocrystals with different shapes are all composed of Cs, Pb and Br elements. There are slight deviations between the experimental atomic ratio and the theoretical value of the three elements as the samples were characterized without any purification.
S-6
Figure S9. Multi-peak fitting of the PL spectra for the 2D CsPbBr3 nanosheets.
The multi-peak-emitting spectra was fitted by the type of Gaussian. The peak positions extracted from the fit are: 452 nm, 478 nm, 489 nm and 516 nm. This result shows the obtained product consists of nanosheets with n = 3, 4, 5 and ∞, respectively, where n represents the number of unit cell layers.
S-7
Figure S10. HRTEM images of the irregular CsPbBr3 nanosheets (a) and its corresponding FFT (b).
The final 2D nanosheets in the manuscript might be formed by the oriented attachment of small single sheets. As shown in Figure S10 (a) and (b), these nanosheets present missing corners and irregular boundaries. We infer that they are grown from small single sheets by the oriented attachment mechanism.
S-8
Table S1. Fitted parameters of the decay curve for CsPbBr3 NCs with various shapes.
CsPbBr3 Samples Single quantum dots (2.4 nm in diameter) Lamellar-structured quantum dots (3.6 nm in diameter) Nanoplatelets (2.3 nm in thickness) Nanosheets (2.4 nm in thickness)
A1 (%)
τ1 (ns)
A2 (%)
τ2 (ns)
A3 (%)
τ3 (ns)
τave (ns)
32.90
2.18
64.21
5.03
2.89
19.16
4.45
47.95
3.56
44.98
9.22
7.08
40.50
8.57
18.48
1.80
74.30
4.23
7.22
11.70
4.33
40.01
2.13
56.94
5.40
3.05
37.09
4.63
Blue emissions of the CsPbBr3 nanocrystals with various shapes are ascribed to the quantum confinement effects (smaller diameters for single and lamellar-structured quantum dots as well as smaller thickness for nanoplatelets and nanosheets compared to the excitonic Bohr diameter). PL decay curve can be well fitted with tri-exponential function, in which the short lifetime (τ1) represents the radiative energy transfer. As shown in table S1, PL radiative lifetimes increased when the quantum-confined sizes increased. This phenomenon indicates, once again, the blue PL emission is due to excitonic recombination.
S-9
Table S2. Photoluminescence quantum yields (PLQY) of the four samples Samples
PLQY (%)
CsPbBr3 Quantum Dots (single)
50.41
CsPbBr3 Quantum Dots (lamellar-structured)
35.70
CsPbBr3 Nanoplatelets (stacked face-to-face)
54.61
CsPbBr3 Nanosheets (2D nanosheets)
47.52
S-10
Shape-controlled Synthesis of All-inorganic CsPbBr3 Perovskite Nanocrystals with Bright Blue Emission Zhiqin Liang1,2 , Suling Zhao1,2, *, Zheng Xu1,2, Bo qiao1,2 , Pengjie Song1,2 , Di Gao1,2 , Xurong Xu1,2
1
Key Laboratory of Luminescence and Optical Information, Beijing Jiaotong
University, Ministry of Education, Beijing, 100044, China 2
Institute of Optoelectronics Technology, Beijing Jiaotong University, Beijing,
100044, China
*
Corresponding author: [email protected]
S-1
Figure S1. (a) TEM image of colloidal CsPbBr3 quantum dots. (b) Size distribution histogram for the samples shown in (a).
Figure S2. EDX spectra of the CsPbBr3 single quantum dots.
S-2
Figure S3. (a) Low-resolution TEM image depicting close-ups of CsPbBr3 lamellar structures. (b and c) Magnified TEM images in (a).
From the magnified TEM images in Figure S3 (b) and (c), we can obviously observe the CsPbBr3 quantum dots grow and align along with the organic mesostructures, thus forming the CsPbBr3 lamellar structures. We infer this phenomenon is related to the organic mesostructures that serve as a soft template.
S-3
Figure S4. Size distribution histogram for the samples shown in Figure S3b.
Figure S5. EDX spectra of the CsPbBr3 lamellar-structured quantum dots.
S-4
Figure S6. Size distribution histogram for the CsPbBr3 nanoplatelets stacking face-to-face.
Figure S7. EDX spectra of the CsPbBr3 nanoplatelets stacked face-to-face.
S-5
Figure S8. EDX spectra of the 2D CsPbBr3 nanosheets.
EDX indicates that these CsPbBr3 nanocrystals with different shapes are all composed of Cs, Pb and Br elements. There are slight deviations between the experimental atomic ratio and the theoretical value of the three elements as the samples were characterized without any purification.
S-6
Figure S9. Multi-peak fitting of the PL spectra for the 2D CsPbBr3 nanosheets.
The multi-peak-emitting spectra was fitted by the type of Gaussian. The peak positions extracted from the fit are: 452 nm, 478 nm, 489 nm and 516 nm. This result shows the obtained product consists of nanosheets with n = 3, 4, 5 and ∞, respectively, where n represents the number of unit cell layers.
S-7
Figure S10. HRTEM images of the irregular CsPbBr3 nanosheets (a) and its corresponding FFT (b).
The final 2D nanosheets in the manuscript might be formed by the oriented attachment of small single sheets. As shown in Figure S10 (a) and (b), these nanosheets present missing corners and irregular boundaries. We infer that they are grown from small single sheets by the oriented attachment mechanism.
S-8
Table S1. Fitted parameters of the decay curve for CsPbBr3 NCs with various shapes.
CsPbBr3 Samples Single quantum dots (2.4 nm in diameter) Lamellar-structured quantum dots (3.6 nm in diameter) Nanoplatelets (2.3 nm in thickness) Nanosheets (2.4 nm in thickness)
A1 (%)
τ1 (ns)
A2 (%)
τ2 (ns)
A3 (%)
τ3 (ns)
τave (ns)
32.90
2.18
64.21
5.03
2.89
19.16
4.45
47.95
3.56
44.98
9.22
7.08
40.50
8.57
18.48
1.80
74.30
4.23
7.22
11.70
4.33
40.01
2.13
56.94
5.40
3.05
37.09
4.63
Blue emissions of the CsPbBr3 nanocrystals with various shapes are ascribed to the quantum confinement effects (smaller diameters for single and lamellar-structured quantum dots as well as smaller thickness for nanoplatelets and nanosheets compared to the excitonic Bohr diameter). PL decay curve can be well fitted with tri-exponential function, in which the short lifetime (τ1) represents the radiative energy transfer. As shown in table S1, PL radiative lifetimes increased when the quantum-confined sizes increased. This phenomenon indicates, once again, the blue PL emission is due to excitonic recombination.
S-9
Table S2. Photoluminescence quantum yields (PLQY) of the four samples Samples
PLQY (%)
CsPbBr3 Quantum Dots (single)
50.41
CsPbBr3 Quantum Dots (lamellar-structured)
35.70
CsPbBr3 Nanoplatelets (stacked face-to-face)
54.61
CsPbBr3 Nanosheets (2D nanosheets)
47.52
S-10
