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Fabini DH, Honasoge K, Cohen A, Bette S, McCall KM, Stoumpos CC, Klenner S, Zipkat M, Hoang LP, Nuss J, Kremer RK, Kanatzidis MG, Yaffe O, Kaiser S, Lotsch BV. Noncollinear Electric Dipoles in a Polar Chiral Phase of CsSnBr 3 Perovskite. J Am Chem Soc 2024; 146:15701-15717. [PMID: 38819106 PMCID: PMC11177262 DOI: 10.1021/jacs.4c00679] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2024] [Revised: 05/14/2024] [Accepted: 05/16/2024] [Indexed: 06/01/2024]
Abstract
Polar and chiral crystal symmetries confer a variety of potentially useful functionalities upon solids by coupling otherwise noninteracting mechanical, electronic, optical, and magnetic degrees of freedom. We describe two phases of the 3D perovskite, CsSnBr3, which emerge below 85 K due to the formation of Sn(II) lone pairs and their interaction with extant octahedral tilts. Phase II (77 K < T < 85 K, space group P21/m) exhibits ferroaxial order driven by a noncollinear pattern of lone pair-driven distortions within the plane normal to the unique octahedral tilt axis, preserving the inversion symmetry observed at higher temperatures. Phase I (T < 77 K, space group P21) additionally exhibits ferroelectric order due to distortions along the unique tilt axis, breaking both inversion and mirror symmetries. This polar and chiral phase exhibits second harmonic generation from the bulk and pronounced electrostriction and negative thermal expansion along the polar axis (Q22 ≈ 1.1 m4 C-2; αb = -7.8 × 10-5 K-1) through the onset of polarization. The structures of phases I and II were predicted by recursively following harmonic phonon instabilities to generate a tree of candidate structures and subsequently corroborated by synchrotron X-ray powder diffraction and polarized Raman and 81Br nuclear quadrupole resonance spectroscopies. Preliminary attempts to suppress unintentional hole doping to allow for ferroelectric switching are described. Together, the polar symmetry, small band gap, large spin-orbit splitting of Sn 5p orbitals, and predicted strain sensitivity of the symmetry-breaking distortions suggest bulk samples and epitaxial films of CsSnBr3 or its neighboring solid solutions as candidates for bulk Rashba effects.
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Affiliation(s)
- Douglas H. Fabini
- Max
Planck Institute for Solid State Research, Stuttgart 70569, Germany
- Department
of Chemistry, Massachusetts Institute of
Technology, Cambridge, Massachusetts 02139, United States
| | - Kedar Honasoge
- Max
Planck Institute for Solid State Research, Stuttgart 70569, Germany
| | - Adi Cohen
- Department
of Chemical and Biological Physics, Weizmann
Institute of Science, Rehovot 76100, Israel
| | - Sebastian Bette
- Max
Planck Institute for Solid State Research, Stuttgart 70569, Germany
| | - Kyle M. McCall
- Department
of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Constantinos C. Stoumpos
- Department
of Materials Science and Technology, University
of Crete, Vassilika Voutes, Heraklion 70013, Greece
| | - Steffen Klenner
- Institut
für Anorganische und Analytische Chemie, Universität Münster, Münster 48149, Germany
| | - Mirjam Zipkat
- Department
of Chemistry, Ludwig-Maximilians-Universität, München 81377, Germany
| | - Le Phuong Hoang
- Max
Planck Institute for Solid State Research, Stuttgart 70569, Germany
| | - Jürgen Nuss
- Max
Planck Institute for Solid State Research, Stuttgart 70569, Germany
| | | | - Mercouri G. Kanatzidis
- Department
of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Omer Yaffe
- Department
of Chemical and Biological Physics, Weizmann
Institute of Science, Rehovot 76100, Israel
| | - Stefan Kaiser
- Max
Planck Institute for Solid State Research, Stuttgart 70569, Germany
| | - Bettina V. Lotsch
- Max
Planck Institute for Solid State Research, Stuttgart 70569, Germany
- Department
of Chemistry, Ludwig-Maximilians-Universität, München 81377, Germany
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Liu S, Wang X, Dou Y, Wang Q, Kim J, Slebodnick C, Yan Y, Quan L. Direct Observation of Circularly Polarized Nonlinear Optical Activities in Chiral Hybrid Lead Halides. J Am Chem Soc 2024; 146:11835-11844. [PMID: 38570347 PMCID: PMC11066869 DOI: 10.1021/jacs.4c00619] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2024] [Revised: 03/17/2024] [Accepted: 03/20/2024] [Indexed: 04/05/2024]
Abstract
Circularly polarized light emission is a crucial application in imaging, sensing, and photonics. However, utilizing low-energy photons to excite materials, as opposed to high-energy light excitation, can facilitate deep-tissue imaging and sensing applications. The challenge lies in finding materials capable of directly generating circularly polarized nonlinear optical effects. In this study, we introduce a chiral hybrid lead halide (CHLH) material system, R/S-DPEDPb3Br8·H2O (DPED = 1,2-diphenylethylenediammonium), which can directly produce circularly polarized second harmonic generation (CP-SHG) through linearly polarized infrared light excitation, exhibiting a polarization efficiency as high as 37% at room temperature. To understand the spin relaxation mechanisms behind the high polarization efficiency, we utilized two models, so-called D'yakonov-Perel' (DP) and Bir-Aronov-Pikus (BAP) mechanisms. The unique zigzag inorganic frameworks within the hybrid structure are believed to reduce the dielectric confinement and exciton binding energy, thus enhancing spin polarization, especially in regions with a high excitation pump fluence based on the DP mechanism. In the case of low excitation pump fluence, the BAP mechanism dominates, as evidenced by the observed decrease in the polarization ratio from CP-SHG measurement. Using density functional theory analysis, we elucidate how the distinctive 8-coordination environment of lead bromide building blocks effectively suppresses spin-orbit coupling at the conduction band minimum. This suppression significantly diminishes spin-splitting, thereby slowing the spin relaxation rate.
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Affiliation(s)
- Sunhao Liu
- Department
of Chemistry, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Xiaoming Wang
- Department
of Physics and Astronomy and Wright Center for Photovoltaics Innovation
and Commercialization, The University of
Toledo, Toledo, Ohio 43606, United States
| | - Yixuan Dou
- Department
of Chemistry, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Qian Wang
- Department
of Chemistry, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Jiyoon Kim
- Department
of Chemistry, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Carla Slebodnick
- Department
of Chemistry, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Yanfa Yan
- Department
of Physics and Astronomy and Wright Center for Photovoltaics Innovation
and Commercialization, The University of
Toledo, Toledo, Ohio 43606, United States
| | - Lina Quan
- Department
of Chemistry, Virginia Tech, Blacksburg, Virginia 24061, United States
- Department
of Materials and Science Engineering, Virginia
Tech, Blacksburg, Virginia 24061, United States
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Arya M, Bhumla P, Sheoran S, Bhattacharya S. Rashba and Dresselhaus effects in doped methylammonium lead halide perovskite MAPbI 3. Phys Chem Chem Phys 2024; 26:10419-10426. [PMID: 38502185 DOI: 10.1039/d3cp04334g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/21/2024]
Abstract
Inorganic-organic lead halide perovskites, particularly methylammonium lead halide (MAPbI3) perovskite, have been regarded as promising materials for optoelectronics and spintronics. However, the practical applications of these perovskites are limited by lead toxicity and instability under air and pressure. This study investigates the substitution of Pb with Sn and Ge in cubic MAPbI3 perovskite. The properties of the resulting hybrid perovskites are compared using state-of-the-art first-principles-based methodologies, viz., density functional theory (DFT) with generalized gradient approximation (PBE) and hybrid functional (HSE06), in conjunction with spin-orbit coupling (SOC). Here, we mainly study the Rashba-Dresselhaus (RD) effect, which arises due to two major mechanisms: (i) the breaking of inversion symmetry (static and dynamic) and (ii) SOC, originating from the presence of heavy elements. We find significant spin-splitting effects in the conduction band minimum and valence band maximum for hybrid perovskites. To gain a deeper understanding of the observed spin-splitting, the spin textures are analyzed, and Rashba coefficients are calculated. We find that the Dresselhaus effect comes into play in substituted hybrid structures in addition to the usual Rashba effect observed in the pristine compound. Additionally, we observe that the strength of Rashba spin-splitting is substantially tuned by the application of uniaxial strain (±5%). Moreover, certain hybrid perovskites exhibit mechanical stability and ductility, making them potential candidates in perovskite-based optoelectronics and spintronics applications.
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Affiliation(s)
- Megha Arya
- Department of Physics, Indian Institute of Technology Delhi, New Delhi, India.
| | - Preeti Bhumla
- Department of Physics, Indian Institute of Technology Delhi, New Delhi, India.
| | - Sajjan Sheoran
- Department of Physics, Indian Institute of Technology Delhi, New Delhi, India.
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Ghosh S, Chowdhury J. Predicting band gaps of ABN 3 perovskites: an account from machine learning and first-principle DFT studies. RSC Adv 2024; 14:6385-6397. [PMID: 38380242 PMCID: PMC10877485 DOI: 10.1039/d4ra00402g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2024] [Accepted: 02/14/2024] [Indexed: 02/22/2024] Open
Abstract
The present paper is primarily focused on predicting the band gaps of nitride perovskites from machine learning (ML) models. The ML models have been framed from the feature descriptors and band gap values of 1563 inorganic nitride perovskites having formation energies <-0.026 eV and band gaps ranging from ∼1.0 to 3.1 eV. Four supervised ML models such as multi-layer perceptron (MLP), gradient boosted decision tree (GBDT), support vector regression (SVR) and random forest regression (RFR) have been considered to predict the band gaps of the said systems. The accuracy of each model has been tested from mean absolute error, root-mean-square error and determination coefficient R2 values. The bivariate plots between the predicted and input band gaps of the compounds for both the training and test datasets have also been estimated. Additionally, two ABN3-type nitride perovskites CeBN3 (B = Mo, W) have been selected and their electronic band structures and optoelectronic properties have been studied from density functional theory (DFT) calculations. The band gap values of the said compounds have been estimated from DFT calculations at PBE, HSE06, G0W0@PBE, G0W0@HSE06 level of theories. The present study will be helpful in exploring the ML models in predicting the band gaps of nitride perovskites which in turn may bear potential applications in photovoltaic cells and optical luminescent devices.
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Affiliation(s)
- Swarup Ghosh
- Department of Physics, Jadavpur University 188, Raja S.C. Mallick Road Kolkata 700032 India
| | - Joydeep Chowdhury
- Department of Physics, Jadavpur University 188, Raja S.C. Mallick Road Kolkata 700032 India
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de Araujo LO, Rêgo CRC, Wenzel W, Silveira DN, Piotrowski MJ, Sabino FP, Pramudya Y, Guedes-Sobrinho D. How cation nature controls the bandgap and bulk Rashba splitting of halide perovskites. J Comput Chem 2023; 44:1395-1403. [PMID: 36805580 DOI: 10.1002/jcc.27094] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2022] [Revised: 02/03/2023] [Accepted: 02/08/2023] [Indexed: 02/23/2023]
Abstract
Because of instability issues presented by metal halide perovskites based on methylammonium (MA), its replacement to Cs $$ \mathrm{Cs} $$ has emerged as an alternative to improve the materials' durability. However, the impact of this replacement on electronic properties, especially gap energy and bulk Rashba splitting remains unclear since electrostatic interactions from organic cations can play a crucial role. Through first-principles calculations, we investigated how organic/inorganic cations impact the electronic properties of MAPbI 3 $$ {\mathrm{MAPbI}}_3 $$ and CsPbI 3 $$ {\mathrm{CsPbI}}_3 $$ perovskites. Although at high temperatures the organic cation can assume spherical-like configurations due to its rotation into the cages, our results provide a complete electronic mechanism to show, from a chemical perspective based on ab initio calculations at 0 K $$ 0\ \mathrm{K} $$ , how the MA $$ \mathrm{MA} $$ dipoles suppression can reduce the MAPbI 3 $$ {\mathrm{MAPbI}}_3 $$ gap energy by promoting a degeneracy breaking in the electronic states from the PbI 3 $$ {\mathrm{PbI}}_3 $$ framework, while the dipole moment reinforcement is crucial to align theory ↔ $$ \leftrightarrow $$ experiment, increasing the bulk Rashba splitting through higher Pb $$ \mathrm{Pb} $$ off-centering motifs. The lack of permanent dipole moment in Cs $$ \mathrm{Cs} $$ results in CsPbI 3 $$ {\mathrm{CsPbI}}_3 $$ polymorphs with a pronounced Pb $$ \mathrm{Pb} $$ on-centering-like feature, which causes suppression in their respective bulk Rashba effect.
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Affiliation(s)
| | - Celso R C Rêgo
- Institute of Nanotechnology Hermann-von-Helmholtz-Platz, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - W Wenzel
- Institute of Nanotechnology Hermann-von-Helmholtz-Platz, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Danilo N Silveira
- Department of Chemistry, Federal University of Paraná, Curitiba, Brazil
| | | | - Fernando P Sabino
- Center for Natural and Human Sciences, Federal University of ABC, Santo André, Brazil
| | - Yohanes Pramudya
- Institute of Nanotechnology Hermann-von-Helmholtz-Platz, Karlsruhe Institute of Technology, Karlsruhe, Germany
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Sheoran S, Monga S, Phutela A, Bhattacharya S. Coupled Spin-Valley, Rashba Effect, and Hidden Spin Polarization in WSi 2N 4 Family. J Phys Chem Lett 2023; 14:1494-1503. [PMID: 36745045 DOI: 10.1021/acs.jpclett.2c03108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Using first-principles calculations, we report the electronic properties with a special focus on the band splitting in the WSi2N4 class of materials. Due to the broken inversion symmetry and strong spin-orbit coupling, we detect coupled spin-valley effects at the corners of the first Brillouin zone (BZ). Additionally, we observe cubically and linearly split bands around the Γ and M points, respectively. The in-plane mirror symmetry (σh) and reduced symmetry of the arbitrary k-point, enforce the persistent spin textures (PST) to occur in full BZ. We induce the Rashba splitting by breaking the σh through an out-of-plane external electric field (EEF). The inversion asymmetric site point group of the W atom introduces the hidden spin polarization in centrosymmetric layered bulk counterparts. Low energy k.p models demonstrate that the PST along the M-K line is robust to EEF and layer thickness, making them suitable for applications in spintronics and valleytronics.
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Affiliation(s)
- Sajjan Sheoran
- Department of Physics, Indian Institute of Technology Delhi, New Delhi, 110016, India
| | - Sanchi Monga
- Department of Physics, Indian Institute of Technology Delhi, New Delhi, 110016, India
| | - Ankita Phutela
- Department of Physics, Indian Institute of Technology Delhi, New Delhi, 110016, India
| | - Saswata Bhattacharya
- Department of Physics, Indian Institute of Technology Delhi, New Delhi, 110016, India
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