Determination of Defect Levels in Melt-Grown All-Inorganic Perovskite

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C: Energy Conversion and Storage; Energy and Charge Transport

Determination of Defect Levels in Melt-Grown All-Inorganic Perovskite CsPbBr Crystals by Thermally Stimulated Current Spectra 3

Mingzhi Zhang, Zhiping Zheng, Qiuyun Fu, Pengju Guo, Sen Zhang, Cheng Chen, Hualin Chen, Mei Wang, Wei Luo, and Yahui Tian J. Phys. Chem. C, Just Accepted Manuscript • DOI: 10.1021/acs.jpcc.8b01532 • Publication Date (Web): 25 Apr 2018 Downloaded from http://pubs.acs.org on April 25, 2018

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The Journal of Physical Chemistry

Schematic diagram of carrier trapping and generating process through the defect levels in TSC measurement. 82x82mm (600 x 600 DPI)

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Figure 1. A typical TSC spectrum of a wafer from the tip part of a stoichiometric CsPbBr3 ingot 59x43mm (600 x 600 DPI)


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Figure 2. (a) I-V curves and (b-d) TSC spectra of CsPbBr3 wafers as a function of regions of a same crystal: (b) the tip, (c) the middle, (c) the tail 99x71mm (600 x 600 DPI)



Figure 3. (a) I-V curves and (b-d) TSC spectra of CsPbBr3 wafers as a function of stoichiometric condition : (b) 1% Pb-poor, (c) stoichiometric, (d) 1% Pb-rich 99x71mm (600 x 600 DPI)


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Figure S1. (a) Defect charge-transition levels calculated by HSE+SOC; (b) Illustration of the formation of shallow levels. 53x19mm (600 x 600 DPI)



Figure S2. Bias-dependent photocurrent of two samples from (a) the tip and the tail part of a same ingot, (b) tip part of a 1% Pb-rich and a 1% Pb-poor crystal 59x24mm (600 x 600 DPI)


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Figure S3. Elemental ratio of wafer as a function of regions of a same crystal 64x49mm (600 x 600 DPI)



Figure S4. Elemental ratio in CsPbBr3 crystals as a function of stoichiometric condition (1% Pb-poor, stoichiometric and 1% Pb-rich) 64x49mm (600 x 600 DPI)


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Determination of defect levels in melt-grown allinorganic perovskite CsPbBr3 crystals by thermally stimulated current spectra Mingzhi Zhang a, Zhiping Zheng * a, Qiuyun Fu a, Pengju Guo a, Sen Zhang a, Cheng Chen a, Hualin Chen a, Mei Wang a,Wei Luo a, Yahui Tian a a

School of Optical and Electronic Information, Engineering Research Center for Functional

Ceramics of the Ministry of Education, Huazhong University of Science and Technology, Wuhan 430074, P. R. China Full affiliation address: No. 1037, Luoyu Road, Hongshan District, Wuhan, Hubei Province, P. R. China, 430074 Corresponding Author * Zhiping Zheng Email: [email protected] Tel: +86-27-87545167

Fax: +86-27-87545167

KEYWORDS: melt-grown CsPbBr3 crystals; intrinsic point defects; thermally stimulated current (TSC) technology; activation energy; defect formation mechanism.


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ABSTRACT: Further improvement of optoelectronic performance is a target for all-inorganic lead halide perovskite material CsPbBr3, however it is greatly limited by quality of the material which is dominated to some extent by defects especially intrinsic point defects. In this study, the intrinsic point defects in melt-grown CsPbBr3 crystals were studied by thermally stimulated current (TSC) technology and simultaneous multiple peak analysis (SIMPA) method. Defect formation mechanism was analyzed systematically by combining the SIMPA fitting results with defect-related parameters, material properties, and external conditions. The main analytical defects, VCs and VBr vacancies, Csi and Pbi interstitials and PbBr antisites, matched up with theoretical prediction well. Such systematic studies of defect types and concentration give us more insights into the carrier transport mechanism of CsPbBr3 and will help us find ways to improve the crystal quality by controlling the types and concentration of point defects. 1. Introduction Compared to the hybrid halide perovskites, all-inorganic lead halide perovskites have attracted a great attention for its better stability.

1-4

Cesium lead bromine (CsPbBr3), as a typical

representative of all-inorganic lead halide perovskites, has been widely studied in the field of optoelectronic devices, such as high-efficiency solar cells, 5 lasers, 6 light-emitting diodes (LED), 7

and high-gain photo-detectors.

8

In view of its relatively high density (4.84 g/cm3) and high

average atomic number (Cs: 55, Pb: 82 and Br: 35), CsPbBr3 is also an attractive detection medium for nuclear radiation.

9-10

In addition, its large band gap (2.25 eV) offers the possibility

of low noise performance at room temperature. 11-12 What is more, CsPbBr3 has a direct band gap and a same order of carrier mobility lifetime products for both electrons and holes (1.7 × 10-3 cm2/V and 1.3 × 10-3 cm2/V for electrons and holes, respectively), implying that no special engineering methodologies are required for patching mismatches between holes and electrons.


9-

2

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10

Thus, this ternary compound shows potential characteristic in optoelectronic performance,

especially in X-ray and γ-ray radiation detection. However, even very low concentration of deep point defects and impurities in the semiconductor crystals can serve as traps and recombination centers that degrade the detector performance.

13-19

Therefore, intrinsic point defects of a semiconductor are always critical to its

optoelectronic performance which is determined by charge carrier transport properties and charge collection efficiency. In order to achieve large carrier mobility lifetime products, control of point defects in radiation detector materials is very essential. In addition, intrinsic defects also determine doping element types and their concentration limit.

20-22

Therefore, it is urgent to

obtain a full understanding of the origin, the distribution and the concentration of intrinsic point defects within detector level CsPbBr3 crystals. Although the theoretical work of the defect formation energies had been done by Jun kang and Lin-Wang Wang,

23

related experimental

investigation has not been found yet. 2. Experimental Section CsPbBr3 single crystal growth. The growth of CsPbBr3 single crystal ingots was conducted in a self-designed vertical two-zone tube furnace by a creative electronic dynamic gradient (EDG) method, and the detailed process was described in our previous work.

24-25

The

detailed procedures of wafer treatment were described in Supporting Information Section 1. Device Fabrication. Au electrode approximately 100 nm thick was made by vacuum evaporation on the well-treated wafer surfaces. Two corresponding electrodes 1 mm in diameter (0.785 mm2 in area) and 6 mm interval were formed on the same surface of wafers. Then the samples annealed under vacuum for more than 2 h to strengthen the metal-semiconductor contact.


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3. Theoretical Basis TSC measurement. Thermally stimulated current (TSC) technology is a simple and effective method for determining the defect levels in semiconductors with high resistivity.

26

In

this paper, TSC technology was used to study the intrinsic point defect signatures in melt-grown semi-insulating (SI) CsPbBr3 single crystals. In TSC measurement, free carriers excited by achromatic light from a halogen lamp were captured by defects at low temperature 18 K. With temperature increasing in the dark from 18 to 315 K at a constant heating rate (0.10 K/s), the trapped electrons and holes were released by thermal emission, and thermally stimulated current was obtained by a Keithley 6514 electrometer under a 10V applied bias. Each peak in the TSC spectrum corresponded to a certain defect level in the band gap which was introduced by a certain defect state in the crystal lattice. The transition levels for different charged defect states were calculated using HSE+SPC by Jun Kang et al, and the results are shown in Supporting Information Figure S1.

23

The

corresponding activation energy of the point defects in Figure S1 is summarized in Table 1. Table 1. Calculated activation energy of intrinsic point defects in CsPbBr3 in Figure S1 (a) 23 The activation energy of donor defects, namely electronic-type defects ( eV ) Defect state

CsBr

Csi

Pbi

PbBr

PbCs

VBr

D1+

0.01603

0.02761

0.21062*

0.05861*

0.03663

0.07072

D2+

0.04465

0.26819

0.48371

D3+

0.62439 The activation energy of acceptor defects, namely hole-type defects ( eV )

Defect state

BrCs

BrPb

CsPb

Bri

VCs

A1-

0.03027*

0.03921

0.14237

0.05611*

0.16743

A2-

0.09024

0.96736

A

3-

VPb 0.14237

1.38036


4

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The simultaneous multiple peak analysis (SIMPA) method was introduced to resolve TSC spectra for a full characterization of defect levels. activation energy (ETi),

27

27-30

Defect-related parameters: thermal

effectively collected charge (QTi),

28

initial defect density (NTi),

30

defect dependent coefficient (Dti) 28 and capture cross section (σni) 29 were obtained by Equations (1) ~ (4). 31-32 Details of mathematical analysis were described in Supporting Information Section 2. The point defects in melt-grown CsPbBr3 crystals were determined by combining the SIMPA fitting results of TSC spectra with the analysis of the distribution of elements. Carrier mobility lifetime product μτ was calculated by fitting photocurrent employing the modified Hecht equation, and 6.384 × 10-4 and 5.412 × 10-4 cm2/V for a tip and a tail wafer of a same crystal were obtained, respectively.

33-34

In the same way, μτ for 1% Pb-rich and 1% Pb-poor crystal

were calculated to be 2.243 × 10-4 and 1.751 × 10-4 cm2/V, respectively. The detailed calculation procedures were described in Supporting Information Section 3.

QTi 



 T4  ETi  k0Tm ln m   β  1 Ti i ITSC dt  ITSC dT  dT  βdt  β T0 QTi NTi  2 μτeAE



m  Dti  3.0  1021 σ ni  m0  *

(1) (2) (3) (4)

Where, in equation (1), ETi is the thermal activation energy of the ith defect which is related to a TSC peak position, k0 is the Boltzmann constant, T is the absolute temperature, and β is the heating rate of the TSC measurement. In Equation (2), QTi is the effective collecting charge which is released from the ith defect level, and ITSCi is the ith individual TSC current peak. In Equation (3), NTi is the ith defect density at the beginning of the temperature rising, e is the electron charge, μ is the carrier mobility, τ is the carrier lifetime, A is the area of electrode, and E is the applied electric field. In Equation (4), Dti is the ith defect dependent coefficient, σni is the


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capture cross section of the ith defect, m0 is the rest mass of a carrier, and m* is the effective mass of the carrier which is calculated to be 0.23 m0 for both holes and electrons at room temperature (for orthorhombic phase). 9 4. Result Figure 1 shows a typical experimental TSC spectrum and its SIMPA fitting results of a CsPbBr3 wafer from the tip part of a stoichiometric CsPbBr3 ingot. The black solid line denotes the measured TSC spectrum, with seven main defect peaks of P1, P2, P3 (SIMPA best fitting P3-1, P3-2, P3-3), P4 (SIMPA best fitting P4-1, P4-2), P5, P6 and P7. Corresponding defect-related parameters calculated from Equations (1) ~ (4) are listed in Table 2. According to the theoretically calculated activation energies of the intrinsic point defects in Table 1, the intrinsic point defects in Figure 1 should be Csi1+, PbBr1+, VBr1+, VCs1-, Pbi1+, Pbi2+ and PbBr2+, respectively. More detailed analysis is given in the Supporting Information Table S3.

Figure 1. A typical TSC spectrum of a wafer from the tip part of a stoichiometric CsPbBr3 ingot


6

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Table 2. Defect-related parameters based on SIMPA best fitting of the TSC spectrum in Figure 1 Peak level (T)

Tm / K

Ea / eV

NT / cm-3

σn / cm2

Possible defect

P1

22.2

0.02821

6.34×1012

1.03×10-14

Csi1+

P2

37.5

0.05428

1.53×1013

1.61×10-14

PbBr1+

P3-1

50.6

0.07851

1.48×1013

P3-2

59.3

0.09513

5.83×1013

P3-3

71.3

0.11911

1.11×1014

P4-1

87.3

0.15178

1.07×1014

P4-2

96.8

0.17183

1.28×1013

P5

117.1

0.21540

3.92×1013

2.02×10-17

Pbi1+

P6

158.2

0.30762

7.70×1012

1.33×10-16

Pbi2+

P7

232.1

0.48175

1.12×1013

1.84×10-17

PbBr2+

P3

P4

Total

1.17×10-14 1.84×1014

1.58×10-15

VBr1+

4.76×10-16 1.20×1014

1.59×10-16

VCs1-

2.35×10-15

3.84×1014

Figure 2 shows the current voltage (I-V) curves, experimental TSC spectra and their SIMPA fitting results of CsPbBr3 wafers as a function of regions of a same crystal. The corresponding defect-related parameters calculated from Equations (1) ~ (4) are presented in Table 3 and more details are given in the Supporting Information Table S3 ~ S5. It was found that the dominant defect in the same ingot changed along the axial direction, i.e. VBr1+ (P3 peak) for the tip part, PbBr2+ (P5 peak) for the middle part, and Pbi1+ (P2 peak) for the tail part, respectively. According to the fitting results in Table 3 and Supporting Information Table S3 ~ S5, the total concentration of the defects had an evident increase along the grown direction, i.e. 3.84 × 1014 cm-3 for the tip, 4.12 × 1014 cm-3 for the middle, and 2.35 × 1015 cm-3 for the tail, respectively. According to the theoretically calculated activation energies of intrinsic point defects in Table 1, the point defects in Figure 2 (b) should be Csi1+, PbBr1+, VBr1+, VCs1-, Pbi1+, Pbi2+ and PbBr2+, in Figure 2 (c) Csi1+, PbBr1+, VCs1-, Pbi1+ and PbBr2+, and in Figure 2 (d) VCs1-, Pbi1+, Pbi2+, PbBr2+ and PbBr3+.


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Figure 2. (a) I-V curves and (b-d) TSC spectra of CsPbBr3 wafers as a function of regions of a same crystal: (b) the tip, (c) the middle, (c) the tail Table 3. Defect-related parameters based on SIMPA best fitting of the TSC spectrum in Figure 2 (b-d) Peak

Tip Region

Middle Region

Tail Region

level

Ea / eV

defect

NT / cm-3

Ea / eV

defect

NT / cm-3

Ea / eV

defect

NT / cm-3

1

0.02821

Csi1+

6.34×1012

0.02341

Csi1+

1.34×1012

0.17491

VCs1-

1.35×1013

2

0.05428

PbBr1+

1.53×1013

0.04624

4.11×1011

0.27705

3

0.07851

1.48×1013

0.05543

3.39×1011

0.29688

4

0.09513

5.83×1013

0.12951

2.35×1013

0.29688

5

0.11911

1.11×1014

0.13843

1.53×1013

0.39792

Pbi2+

6.68×1013

6

0.15178

1.07×1014

0.21635

1.35×1011

0.46616

PbBr2+

7.51×1013

7

0.17183

VCs1-

1.28×1013

0.52541

2.22×1014

0.55708

8

0.21540

Pbi1+

3.92×1013

0.52541

5.89×1013

0.59431

9

0.30762

Pbi2+

7.70×1012

0.52541

9.01×1013

0.61587

10

0.48175

PbBr2+

1.12×1013

Total

3.84×1014

VBr1+

PbBr1+ VCs1Pbi1+ PbBr2+

3.71×1014 Pbi1+

7.57×1014

3.59×1014 PbBr3+

0.63042 Total

4.12×1014


1.38×1014

3.04×1014 1.87×1014 7.99×1013

Total

2.35×1015

8

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Figure 3 shows the I-V curves, experimental TSC spectra and their SIMPA fitting results of CsPbBr3 wafers as a function of stoichiometric condition (1% Pb-poor, stoichiometric and 1% Pb-rich). Corresponding defect-related parameters together with possible point defects are presented in Table 4, and more detail analyses are given in the Supporting Information Table S3, S6, and S7. Compared to the stoichiometric crystal having concentration of defects of 3.84 × 1014 cm-3, the off-stoichiometric crystals for the 1% Pb-poor crystal (8.18 × 1014 cm-3) and for the 1% Pb-rich crystal (1.57 × 1017 cm-3) have higher concentration of defects.

Figure 3. (a) I-V curves and (b-d) TSC spectra of CsPbBr3 wafers as a function of stoichiometric condition : (b) 1% Pb-poor, (c) stoichiometric, (d) 1% Pb-rich


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Table 4. Defect-related parameters based on SIMPA best fitting of TSC spectra in Figure 3 (b-d) Peak

1% Pb-poor

Stoichiometric

1% Pb-rich

level

Ea / eV

defect

NT / cm-3

Ea / eV

defect

NT / cm-3

Ea / eV

defect

NT / cm-3

1

0.02857

Csi1+

5.65×1013

0.02821

Csi1+

6.34×1012

0.02926

Csi1+

3.97×1016

2

0.06441

2.66×1013

0.05428

PbBr1+

1.53×1013

0.05565

PbBr1+

7.76×1016

3

0.08848

1.75×1013

0.07851

1.48×1013

0.17192

4

0.13848

CsPb1-

9.45×1013

0.09513

5.83×1013

0.17192

5

0.21901

Pbi1+

7.71×1013

0.11911

1.11×1014

0.52960

6

0.25961

6.11×1013

0.15178

1.07×1014

0.52960

7

0.28920

1.24×1014

0.17183

8

0.31669

1.82×1014

0.21540

Pbi1+

3.92×1013

9

0.34781

1.20×1013

0.30762

Pbi2+

7.70×1012

10

0.39620

2.08×1013

0.48175

PbBr2+

1.12×1013

11

0.50422

12

0.51880

Total

3.84×1014

VBr1+

Pbi2+

PbBr2+

VBr1+

VCs1-

VCs1PbBr2+

1.57×1017 1.19×1016 6.19×1017 6.70×1017

1.28×1013

6.91×1013 7.63×1013

Total

8.18×1014

Total

1.57×1017

5. Discussion As is known, CsPbBr3 is a direct band gap semiconductor with a wide band gap of 2.25 eV. The states around the band gap come from Br and Pb atoms, whereas Cs has no contribution. In the valence band, the Pb s and Br p states have strong hybridization, and their antibonding interaction leads to the formation of the upper valence band. On the other hand, the conduction band is formed through the coupling between the empty Pb p states. Because of the ionic character of CsPbBr3, the antibonding interactions between the valence band and conduction band states are negligible, so the lower conduction bands have almost no contribution from Br atoms.

23

Such lacking of bonding-antibonding interaction between the conduction bands and

valence bands leads to high defect tolerance in CsPbBr3. 35


10

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The Cs-based defect, i.e. Vcs vacancy is a common defect with the lowest formation energy of 0.01603 eV in CsPbBr3. CsPbBr3 has an ABX3 type perovskite structure and go through two successive phase transitions. With the temperature decrease during crystal growth, the crystal structure of CsPbBr3 transforms from cubic (space group Pm-3m, 221) to tetragonal (space group P4/mbm, 99) at 130 °C and to orthorohombic (space group Pbnm, 62) at 88 °C.

24

[PbBr6]

octahedra, the core structure in CsPbBr3, with a Pb2+ cation bonded to six bromide ions, gradually disorders with the temperature decrease. Cation Cs+ ions locate in the octahedra voids to form a stable structure. Compared to the organic cation ( radius 1.8 Å for MA+, 2.3 Å for EA+, and 2.3 Å for DMA+),

36

Cs+ ions (1.67 Å) has a relative small radius, therefore the Cs+ ions

could migrate easily between the voids.

37

Apart from that, the high temperature in the melt-

grown process of crystals promotes this migration. According to the theoretically calculation, the intrinsic VCs has low formation energy especially in Pb-rich/Br-poor CsPbBr3 crystals.

23

In

addition, the measured elemental ratio of all our melt-grown crystals are Pb-rich, as shown in the Supporting Information Figure S3, S4, indicated that VCs can be easily formed in the crystals. The majority of Vcs vacancies are formed because of the Cs-poor situation and the minority of Vcs vacancies are formed by Frenkel effect. The forming process can be described:

CsCs  Csi  VCs

(5)

The Br-based defect, i.e. VBr vacancy has a relatively low formation energy 0.16 eV according to the theoretical calculation.

38

Shallow halogen vacancies can be easily formed in

halide optoelectronic materials including the all-inorganic halide perovskite CsPbBr3.

39

According to the study of Mao-Hua Du et al, VBr+ is the most stable state in the crystals where Fermi level is near the mid-gap.

39

Note that the melt-grown CsPbBr3 crystals had a high

resistivity (deduced from the I-V curves in Figure 2 (a) and Figure 3 (a)), thus the Fermi level is


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near the mid-gap and VBr+ is the most stable state in the melt-grown crystals. Furthermore, for the melt-grown CsPbBr3, VBr vacancies is apt to form due to high Br vapor pressure under melt grown situation, 40 and the forming process can be described:

BrBr  VBr 

1 Br2  2

(6)

The Pbi interstitial can be introduced in crystals because of the crystal structure disorder and Pb-rich characteristic in the melt-grown CsPbBr3 crystals. Compared to that in the cubic and tetragonal phases, the [PbBr6] octahedra in the orthorhombic phase are slightly tilted. The detailed structure parameters (octahedra volume, bond distance and bond angle of Pb-Br) are shown in Supporting Information Table S2. Obviously, with the temperature decrease, the bond distance and bond angles have a slight expansion (0.6% ~ 1.6%), however the octahedra volumetric expansion is obvious (more than 3%). The distortion of [PbBr6] octahedra makes the possibility of lead-based defect formation. In the melt-grown CsPbBr3 crystals, high temperature and temperature gradient during crystal growth process are “the chief culprit” for defect formation. As shown in Table 3, Table 4 and Supporting Information Figure S3, S4, it can be seen: 1) all our melt-grown crystals are of experimentally measured Pb-rich, 2) the measured concentration of Pb-based defects (including Pbi interstitials and PbBr antisites) in the Pb-rich crystal is 3 ~ 4 order of magnitudes higher than that in the stoichiometric crystal, 3) Pb element had an in-homogeneous distribution along the crystal growth direction inside the crystals, and the concentration of Pb-based defects increased sharply from the tip to the tail of a crystal. Therefore, the excess Pb atoms, especially in the Pbrich crystals and the tail part of a crystal, may occupy the interstitial sites. In conclusion, the disorder of the [PbBr6] octahedra makes the possibility of defect formation, and the high temperature gradient during crystal growth and Pb-rich condition


12

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promote the Pb-based defect formation. Note that a certain concentration (9.45 × 1013 cm-3) of Pb vacancies (VPb2- or CsPb1-) in the Pb-poor crystal, and it indicates that a small amount of Pbi was caused by the Frenkel effect, and the forming process can be described as:

PbPb  Pbi  VPb

(7)

The PbBr antisites may be generated by the nonradiative recombination which combination VBr vacancies with Pbi interstitials. According to the analysis above, VBr vacancies and Pbi interstitials have a certain concentration within the melt-grown CsPbBr3 crystals. The formation of PbBr antisites can be expressed as follow:

VBr  Pbi  PbBr

(8)

The concentration of PbBr increases sharply from the tip to the middle of a crystal because of the enrichment of Pb element along the growth direction. However the concentration of PbBr increases slowly from the middle to the tail of a crystal because of the gradual exhaustion of VBr. Among the crystals with different stoichiometric condition, the Pb-rich one has the highest concentration of Pb-based defects and the stoichiometric crystal has the lowest concentration of defects because of the role of stoichiometry in the growth of large single crystal. 41 Therefore the concentration of Csi, Pbi, and PbBr in the Pb off-stoichiometric is higher than that in the stoichiometric crystal. 6. Conclusions In summary, the intrinsic point defects in melt-grown CsPbBr3 crystals were investigated systematically by TSC technology. Five possible intrinsic point defects, namely, VCs and VBr vacancies, Csi and Pbi interstitials and PbBr antisites were found in the CsPbBr3 crystals. VCs was the common defect due to the low formation energy (ΔHCs) especially in Pb-rich samples. Shallow defect VBr was easily formed in CsPbBr3 because of the high Br vapor pressure. The


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formation of Pbi originated from the Pb deviation in samples and the expansion of [PbBr6] octahedra induced by the distortion with the temperature decrease. The high temperature and temperature gradient were the “the chief culprit” for promoting the formation of VCs, VBr and Pbi defects in melt-grown crystals. PbBr antisites were generated by nonradiative recombination of VBr vacancies and Pbi interstitials. The distribution rule of the defects under different conditions was also acquired. The concentration of Pb-based defects increased sharply from the tip to the tail of a crystal. However the concentration of PbBr increased slowly from the middle to the tail because of the gradual exhaustion of VBr. As for the crystals under various stoichiometric conditions, the concentration of PbBr in the Pb-rich crystals was 3 ~ 4 order of magnitudes higher than that in the stoichiometric crystals. Compared to the Pb off-stoichiometric crystals, the stoichiometric crystals have the lowest concentration of defects. Such systematically experimental studies of intrinsic point defects in melt-grown CsPbBr3 crystals can help us to know more about the internal carrier transport mechanism, and and therefore can also help us to determine doping elements and their limit for improving the crystal quality by achieving low density of point defects. ASSOCIATED CONTENT Supporting Information The detailed procedures of wafer treatment, theoretical formula analysis of TSC measurement and SIMPA method, the calculation of carrier mobility lifetime product (μτ) and the detailed defect-related fitting parameters of TSC spectra. (PDF)


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AUTHOR INFORMATION Corresponding Author * E-mail: [email protected]. ORCID

Zhiping Zheng: 0000-0002-9613-2117 Mingzhi Zhang: 0000-0002-7113-4634 Notes

The authors declare no competing financial interest. ACKNOWLEDGMENTS This work was financially supported by the National Natural Science Foundation of China under Grant Nos. 11575065 and 11275078. The authors acknowledge the assistance of the Analytical and Testing Center (ATC) and State Key Laboratory of Material Processing and Die & Mold Technology of Huazhong University of Science and Technology (HUST). The authors also wish to express their hearty thanks to State Key Laboratory of Solidification Processing of Northwestern Polytechnical University for thermally stimulated current spectra testing. REFERENCES (1) Rakita, Y.; Kedem, N.; Gupta, S.; Sadhanala, A.; Kalchenko, V.; Böhm, M. L.; Kulbak, M.; Friend R. H.; Cahen, D.; Hodes, G. Low-Temperature Solution-Grown CsPbBr3 Single Crystals and Their Characterization. Cryst. Growth Des. 2016, 16(10), 5717-5725. (2) Li, G.; Wang, H.; Zhu, Z.; Chang, Y.; Zhang, T.; Song, Z.; Jiang, Y. Shape and phase evolution from CsPbBr3 perovskite nanocubes to tetragonal CsPb2Br5 nanosheets with an indirect bandgap. Chem. Commun. 2016, 52(75), 11296-11299.


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Determination of Defect Levels in Melt-Grown All-Inorganic Perovskite

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