Shuaib Y-basedComprehensive mahmudj.pptx

double halide perovskite

1. Welcome To my presentation 1

2. DFT investigation of Sc and Y based inorganic double perovskite halides, A 2 BB′X 6 (A= Cs, Rb , B= Au, B ′= Sc , Y, X= Cl , Br, I) for energy harvesting technology Shuaib Mahmud ID No: 20PHY003P Session: 2020-21 Department of Physics Chittagong University of Engineering & Technology (CUET) Chittagong-4349, Bangladesh 2 Supervisor Prof. Dr. Md. Ashraf Ali

3. 3 Introduction Literature Review Motivation Objectives Computational technique/Methodology Results and discussion Conclusions Content

4. 4 Introduction Perovskite CaTiO 3 (ABX 3 ) The mineral was discovered in the Ural Mountains of Russia by Gustav Rose in 1839 and is named after Russian mineralogist Lev Perovski (1792–1856 ). The chemical formula for double perovskite materials is A 2 BB′X 6 . A = Cs + , Rb + , B = Au + , B' = Sc 3+ /Y 3+ , X = Cl - /Br - / I -

5. W hy do we choose the double perovskite halide materials? Enhanced stability: Thermal and chemical. Tunable properties: B and B' Reduced band gap Improved charge transport 5

6. Literature review 6 Author Compounds Properties studied Application(s) K. Radja et al. Cs 2 AgFeCl 6 Structural, magneto-electronic, elastic, mechanical and thermoelectric Thermo-electric based instrument N. A. Noor et al. A 2 ScInI 6 (A= Rb , Cs) Structural, mechanical, electronic and optical IR part of renewable energy devices F. Aslam et al. Cs 2 InBiX 6 (X= Cl , Br, I)   Structural and opto-electronic Solar absorbing devices S. A. Dar et al. Cs 2 ScInCl 6 Structural, mechanical, electronic and optical   IR part of optoelectronic devices N. Erum Cs 2 ScTlX 6 (X = Cl , Br, I) Mechanical, optoelectronic and thermoelectric Conversion devices D.-Y. Hu et al Cs 2 CuBiX 6 (X= I, Br, Cl) structural, elastic, electronic and optical Photosensitive materials of solar cells Aldaghfag, Shatha A., et al. X 2 ScAgCl 6 (X= K, Na) electronic, optical and thermoelectric Solar cell and thermo-electric devices

7. 7 Author Compounds Properties studied Application(s) Mumtaz Manzoor et al. Rb 2 LiTlX 6 Opto-electronic and transport Solar cell Muskan Nabi et al. Cs 2 CuMCl 6 (M = Sb , Bi) Electronic ,optical and TE Green technology J.A.A et al. Pb 2 ScBiO 6 Structural, electronic, optical, thermoelectric Absorbing material Maryam Babaei et al. Cs 2 AgSbX 6 (X= Cl , Br, I) Opto -electro-mechanical Solar cell Radhakrishnan Anbarasan et al. Cs 2 AgInX 6 (X = Cl, Br, I) Structural, mechanical, electronic, and optical Photo-volataic Mazia Asghar et al. Rb 2 ScAgX 6 (X = Cl, Br, I) Opto -electronic and TE Solar cell Suhail A. Dar et al. Cs 2 XRhCl 6 (X= K, Na) stability and optoelectronic Absorbing material G. M. Mustafa et al. Cs 2 AgAsX 6 (X = cl, br , I) optoelectronic, thermoelectric, mechanical Solar cell and energy harvesting

8. Motivation 8 These Double perovskites compounds are ( A 2 AuYX 6 (A= Cs, Rb and X= Cl , Br, I) composed of abundant and non-toxic elements, making them environmentally friendly with along the cost effective and time efficient. No theoretical or practical work has been done on these substances in order to determine physical property qualities via DFT computation . The comprehensive study of double perovskites also contributes to fundamental scientific understanding.

9. Objectives 8 To study the structural stability such as tolerance factor, octahedral factor, formation energy and binding energy. To check the thermo-dynamical stability of compound. To study the mechanical stability and elastic behavior. To find out the energy gap of band structure and electron density of states. To find the suitability for use in solar cells and/or thermoelectric devices .

10. Computational Technique/Methodology 10 Schrödinger equation: Ĥ = wave function Ĥ= Hamiltonian operator  

11. 11 Born Oppenheimer Approximation Minimum 3 orders of magnitude mass difference between electrons and nuclei, i.e. any change in the position of nuclei corresponds to an immediate update the position of electron “ Nuclei is fixed with respect to electrons ”.

12. 12 Where, ᴪ elec is a function of electron position only, and it gives the lowest E elec is termed as ground state . How can be measured of ᴪ elec ? The probability is given by = Hartree product

13. 13 Density Functional techniques are based on two theorem, proved by Hohenberg and Kohn (1964) : Theorem 1: The ground state energy E is the unique functional of Electron density . E = E [ ρ (r)] Theorem 2: The electron density that minimizes the energy of the overall functional is the true ground state electron density. E[ ρ (r)] > E [ ρ (r)]

14. 14 Wien2k FP-LAPW: interstitial region and atomic sphere. SCF (self consistent field)- solving the K ohn S hams equations. Fig.1: Flowchart for DFT calculation

15. Results & Discussion Structural parameter Cubic structure(a = b = c; α = β = γ = 90 ⁰ ) Space group (Fm-3m, 225) Cs (0.25, 0.25, 0.25), Au(0.5 , 0.5, 0.5), Y (0, 0, 0), and Cl /Br/I (0.25, 0, 0 ). Four formula unit (2:1:1:6) Cs= 8, Au= 4, Y= 4, X= 24 Fig.2: Unit cell of a) Cs 2 AuYX 6 and b) Rb 2 AuYX 6 15

16. Structural stability Tolerance factor (T F ) Octahedral factor ( μ ) Formation energy Binding energy [1] [1] [2] [2]   T F = 0.81 to 1.1 [1] [1 ] = negative value [2] = negative value [2]   16 Liu , Xiang Chun ; Hong, Rongzi ; Tian , Changsheng (24 April 2008). "Tolerance factor and the stability discussion of ABO 3 type ilmenite ".  Journal of Materials Science: Materials in Electronics .  20  (4): 323–327 X . Du, D. He, H. Mei, Y. Zhong , and N. Cheng, “Insights on electronic structures, elastic features and optical properties of mixed-valence double perovskites Cs 2 Au 2 X 6 (X= F, Cl , Br, I),” Phys. Lett . A , vol. 384, no. 8, p. 126169, 2020.

17. Table.1: Different structural stability factor Parameter Cs 2 AuYCl 6 Cs 2 AuYBr 6 Cs 2 AuYI 6 Rb 2 AuYCl 6 Rb 2 AuYBr 6 Rb 2 AuYI 6 a=b=c (Ǻ) 10.7811 11.3529 12.1495 10.7261 11.2605 12.0988 T F 0.88 0.87 0.86 0.85 0.84 0.83 µ 0.62 0.57 0.51 0.62 0.57 0.51 E F (eV/atom) -2.45 -2.07 -1.62 -2.41 -2.02 -1.57 E b (eV/atom) -4.18 -3.81 -3.41 -4.16 -3.78 -3.37 19

18. D ynamic stability Fig.3: Cs based phonon dispersion with total and partial DOS of Cs 2 AuYX 6 ; X= Cl , Br, I 20

19. Fig. 4: Rb based phonon dispersion with total and partial DOS of Rb 2 AuYX 6 ; X= Cl , Br, I 19

20. Formation of competing phase energy, ∆ H cp = E(Compound) – E(A) – E(B); ∆ H cp < 0 For Rb series Where, X= Cl , Br and I   ∆ H cp ( = -17 meV /atom ∆ H cp ( = -10 meV /atom ∆ H cp ( = -5 meV /atom   For Cs series Where, X= Cl , Br and I   ∆ H cp ( = - 25 meV /atom ∆ H cp ( = -18 meV /atom ∆ H cp ( = - 12 meV /atom   Thermo-dynamic stability 22

21. Electronic properties Band structure DOS (TDOS and PDOS) Table.3: Band gap values of studied compounds Parameter Cs 2 AuYCl 6 Cs 2 AuYBr 6 Cs 2 AuYI 6 Rb 2 AuYCl 6 Rb 2 AuYBr 6 Rb 2 AuYI 6 Band gap (eV) GGA-PBE 2.06 1.57 1.05 2.07 1.60 1.07 TB- mBJ [3] 2.86 2.36 1.74 2.91 2.40 1.78 23 [3] Tran , Fabien, and Peter Blaha . "Accurate band gaps of semiconductors and insulators with a semi local exchange-correlation potential."  Physical review letters  102.22 (2009): 226401.

22. 22 Fig.5: Energy band structure of a) Cs 2 AuYCl 6 b) Cs 2 AuYBr 6 , c) Cs 2 AuYI 6 by GGA-PBE and TB- mBJ method.

23. 23 Fig.6: Energy band structure of d ) Rb 2 AuYCl 6 e) Rb 2 AuYBr 6 f) Rb 2 AuYI 6 by GGA-PBE and TB- mBJ method.

24. Fig.7: Total and partial DOS of Cs- based Cs 2 AuYCl 6 , Cs 2 AuYBr 6 and Cs 2 AuYI 6 by TB- mBJ method 24

25. Fig.8: Total and partial DOS of Rb - based Rb 2 AuYCl 6 , Rb 2 AuYBr 6 and Rb 2 AuYI 6 by TB- mBJ method 25

26. 26 Effective mass of charge carrier   Table.4: Effective masses of holes and electrons of Y based compound. Compound Approach m h */m m e */m Cs 2 AuYCl 6 GGA-PBE TB- mBJ 0.35 0.40 0.11 0.14 Cs 2 AuYBr 6 GGA-PBE TB- mBJ 0.29 0.31 0.08 0.12 Cs 2 AuYI 6 GGA-PBE TB- mBJ 0.25 0.25 0.07 0.08 Rb 2 AuYCl 6 GGA-PBE TB- mBJ 0.34 0.39 0.11 0.13 Rb 2 AuYBr 6 GGA-PBE TB- mBJ 0.28 0.30 0.08 0.12 Rb 2 AuYI 6 GGA-PBE TB-mBJ 0.24 0.25 0.06 0.08

27. 27 Fig.9: Charge density mapping of Cs and Rb based halides.

28. 28 Optical properties

29. 29 Fig. 10 a ) real part of the dielectric constant, b) imaginary part of the dielectric constant, c) absorption coefficient in eV and d) absorption coefficient in nm e) optical reflectivity and f) loss function for Y based compounds of Cs 2 AuYCl 6 , Cs 2 AuYBr 6 , Cs 2 AuYI 6 , Rb 2 AuYCl 6 , Rb 2 AuYBr 6 , and Rb 2 AuYI 6 .

30. 30 Thermoelectric properties

31. 31 Fig 11: a) Electrical conductivity (σ), b) Electronic conductivity ( Ke ), c) Lattice thermal conductivity, d) Total thermal conductivity, e) See-beck coefficient (S), f ) power factor (PF), g ) Figure of merit (ZT)

32. 32 Table 5 : Room temperature computed values of electrical conductivity (σ), electronic conductivity ( Ke ), Lattice thermal conductivity, See-beck coefficient (S), power factor (PF), and figure of merit (ZT) of the studied compounds by TB- mBJ approach. Compound σ ×10 5 (1/Ω.m) K e (Wm -1 k -1 ) K L (Wm -1 k -1 ) S (μV/K) PF ×10 -3 (Wm -1 k -2 )   ZT Cs 2 AuYCl 6 0.94 0.37 0.33 195 3.57 0.51 Cs 2 AuYBr 6 1.02 0.42 0.31 195 3.58 0.53 Cs 2 AuYI 6 0.93 0.39 0.28 206 3.94 0.58 Rb 2 AuYCl 6 1.01 0.4 0.26 189 3.62 0.55 Rb 2 AuYBr 6 1.02 0.42 0.21 197 3.94 0.62 Rb 2 AuYI 6 0.90 0.38 0.14 209 3.95 0.75

33.   Nature of compounds depends on Young’s Modulus (Y) Bulk Modulus (B) Shear Modulus (G) Pugh's ratio (B/G) Poisson's ratio ( ) Cauchy's pressure ( Cp )   1.75 < ductile; 0.26 < ductile 0 < ductile 33 Mechanical stability C 11 > 0, C 11 - C 12 > 0; C 11 + 2C 12 > 0; C 44 > 0 and C 11 > B > C 12 [4] 4 . M. Born, K. Huang, and M. Lax, “Dynamical theory of crystal lattices,” Am. J. Phys. , vol. 23, no. 7, p. 474, 1955.

34. Table.6: Elastic and thermo-mechanical parameter 34 Elastic constant Cs 2 AuYCl 6 Cs 2 AuYBr 6 Cs 2 AuYI 6 Rb 2 AuYCl 6 Rb 2 AuYBr 6 Rb 2 AuYI 6 C 11 ( GPa ) 54.27 47.87 37.60 56.52 45.80 37.83 C 12 ( GPa ) 20.56 16.59 14.33 20.76 17.01 14.51 C 44 ( GPa ) 9.60 8.89 8.61 8.18 7.23 5.37 B( GPa ) 31.80 27.02 22.09 32.68 26.60 22.28 G( GPa ) 12.05 11.16 9.71 11.25 9.56 7.37 Y(GPa) 32.10 29.44 25.42 28.34 25.62 19.91 B/G   2.63   2.42   2.27   2.90   2.78 3.02   0.33 0.32 0.31 0.35 0.34 0.35 CP = C 12 -C 44   10.96 7.7     5.72   12.58 9.78   9.14   A   0.57   0.56   0.74   0.46   0.50 0.46   Density(g/cm 3 ) 4.05 4.68 4.86 3.60 4.35 4.56 Ɵ D (k) 182.91 155.26 132.58 188.71 150.60 120.35 Tm (±300k) 873.73 835.91 775.21 887.03 823.67 776.57 K min (Wm -1 k -1 ) 0.27 0.22 0.17 0.28 0.21 0.16 Elastic constant Cs 2 AuYCl 6 Cs 2 AuYBr 6 Cs 2 AuYI 6 Rb 2 AuYCl 6 Rb 2 AuYBr 6 Rb 2 AuYI 6 C 11 ( GPa ) 54.27 47.87 37.60 56.52 45.80 37.83 C 12 ( GPa ) 20.56 16.59 14.33 20.76 17.01 14.51 C 44 ( GPa ) 9.60 8.89 8.61 8.18 7.23 5.37 B( GPa ) 31.80 27.02 22.09 32.68 26.60 22.28 G( GPa ) 12.05 11.16 9.71 11.25 9.56 7.37 Y(GPa) 32.10 29.44 25.42 28.34 25.62 19.91 B/G   2.63   2.42   2.27   2.90   2.78 3.02   0.33 0.32 0.31 0.35 0.34 0.35 CP = C 12 -C 44   10.96 7.7     5.72   12.58 9.78   9.14   A   0.57   0.56   0.74   0.46   0.50 0.46   Density(g/cm 3 ) 4.05 4.68 4.86 3.60 4.35 4.56 Ɵ D (k) 182.91 155.26 132.58 188.71 150.60 120.35 Tm (±300k) 873.73 835.91 775.21 887.03 823.67 776.57 K min (Wm -1 k -1 ) 0.27 0.22 0.17 0.28 0.21 0.16

35. Conclusions: 35 The all compounds (Y-based) are thermo-dynamically and mechanically stable, except . Rb 2 AuYI 6 which is dynamically unstable. Among the studied materials, the I-based DPs exhibit favorable band with a high absorption coefficient (in the order of 10 5 ), expected to be potential absorbing materials for solar cells. The other compounds are also like to be suitable for same. The Rb based halides are also less like to be potential candidates for use thermoelectric devices.

36. 36 Publication Publication S. Mahmud , M. A. Ali , M. M. Hossain, M. M. Uddin “DFT aided prediction of phase stability, optoelectronic and thermoelectric properties of A 2 AuScX 6 (A= Cs, Rb ; X= Cl , Br, I ) double perovskites for energy harvesting technology” Vacuum 221 ( 2023 ) 112926. IF 4.11 Acknowledgement W e are grateful to the Advanced Computational Materials Research Laboratory (ACMRL) , department of physics, CUET, for providing the lab facility and UGC Ph.D. fellowship program 2022-23 for financial support during this study.

37. THANK YOU! 37