Search query: circular dichroism  hybrid perovskites

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abstract: Free carrier absorption (FCA) in a semiconductor provides information about the band on which the free carriers reside, and in the classical limit, follows the o 2 law with o being the photon frequency. In hybrid organic inorganic perovskites (HOIPs) the colossal Rashba effect (RE) results in a new band dispersion, characterized by wavevector |k| k0 of band extremum and effective mass m* Here we show that the colossal RE in two dimensional HOIPs greatly enhances phonon assisted FCA with a modified frequency dependence and induces a direct transition between the subbands with a resonance at o 4R 22k02/m* which, under a magnetic field, exhibits a strong oscillatory magnetic circular dichroism (MCD) The MCD spectrum allows a complete and reliable determination of k0 and m* for conduction and valence bands in HOIPs and helps reveal the microscopic mechanism of their outstanding photovoltaic performance.
author_names: Zhi-Gang Yu
title: Oscillatory Magnetic Circular Dichroism of Free Carrier Absorption and Determination of the Rashba Dispersions in Hybrid Organic Inorganic Perovskites.
venue: The journal of physical chemistry letters
year: 2018

abstract: By incorporating various halogen (F, Cl, Br, and I) substituted chiral organic cations, the effects of chiral molecules on chiroptical properties of hybrid organic inorganic perovskite (HOIP) are investigated. Among them, the HOIP having Cl substituted chiral cation exhibits the highest circular dichroism (CD) and circular polarized luminescence (CPL) intensities, indicating the existence of the largest rotatory strength, whereas the F substituted one shows the weakest intensities. The observed modulation can be correlated to the varied magnetic transition dipole of HOIPs, which is sensitive to the d spacing between inorganic layers and the halogen halogen interaction between organic cations and the inorganic sheets. Although a larger angular momentum of organic cation is expected as the atomic number of the para substituent increases, the simultaneous increase in atom size enlarges the d spacing of the HOIPs, thereby lowering the magnetic transition dipole. However, the strong halogen halogen interaction existing in Cl substituted system leads to a significantly increased rotational strength. These offsetting effects meet the optimal CD and CPL intensity with chlorine substitution, rendering the rotatory strength of HOIPs arranged in the order of (ClMBA) 2 PbI 4 (BrMBA) 2 PbI 4 (IMBA) 2 PbI 4 (MBA) 2 PbI 4 (FMBA) 2 PbI 4 The modulation of the magnetic transition dipoles of HOIP paves the new avenue for designing hybrid perovskite based spintronic devices.
author_names: Lan-Sheng Yang

Yi-Hung Liu

Pi-Tai Chou

Ching-Wen Chiu
title: Tuning the Circular Dichroism and Circular Polarized Luminescence Intensities of Chiral 2D Hybrid Organic Inorganic Perovskites through Halogenation of the Organic Ions.
venue: Angewandte Chemie
year: 2021

abstract: Metal halide perovskites are recently emerging as the promising alternative for CPL detection owing to their CPL sensitive property induced by chiral organics and efficient charge transport of inorganic frameworks. However, most of these reported chiral perovskites involve high concentrations of toxic Pb which will become the potential bottleneck for their further application. Herein, we successfully developed two lead free halide double perovskites, R b MPA] 4 AgBiI 8 R b MPA R b methylphenethylammonium, 1 R and S b MPA] 4 AgBiI 8 S b MPA S b methylphenethylammonium, 1 S Circular dichroism measurements reveal that these perovskites exhibit notable chirality induced by organic cations to distinguish different polarization states of CPL photons. Significantly, they present unique chiral polar photovoltaic, and resulting self powered CPL detection without an external power source is unprecedentedly achieved. Furthermore, an anisotropy factor up to 0.3 is acquired for the self powered CPL detection, reaching the highest value among reported chiral perovskites. This work suggests hybrid double perovskites are promising photoelectronic candidates, and provides a new approach for exploring new "green" circularly polarized light sensitive materials with high perfromance
author_names: Dong Li

Xitao Liu

Wentao Wu

Yunyan Peng

Sangen Zhao

Lina Li

Maochun Hong

Junhua Luo
title: Chiral lead free hybrid perovskites for self powered circularly polarized light detection.
venue: Angewandte Chemie
year: 2020

abstract: Using circularly polarised broadband transient absorption, time resolved circular photoluminescence, and transient Faraday rotation spectroscopy, we report that spin dependent interactions have a significant impact on exciton energies and spin depolarisation times in layered Ruddlesden Popper hybrid metal halide perovskites. In BA2FAPb2I7, we report that room temperature spin lifetimes are largest (3.2 ps) at a carrier density of ~1015 cm 3, while the exciton depolarisation rate increases with exciton density. This indicates that many body interactions reduce spin lifetimes, and outcompete the effect of D'yakonov Perel precessional relaxation that has been previously reported at lower carrier densities. samples. We further observe a dynamic circular dichroism that arises from a photoinduced polarisation in the exciton distribution between total angular momentum states. Our findings provide fundamental, application relevant insights into the spin dependent exciton exciton interactions in layered hybrid perovskites.
author_names: Sean A Bourelle

Ravichandran Shivanna

Franco V A Camargo

Soumen Ghosh

Alexander J Gillett

Satyaprasad P Senanayak

Sascha Feldmann

Lissa F L Eyre

Arjun Ashoka

Tim van de Goor

Haralds Abolins

Thomas Winkler

Giulio Cerullo

Richard H Friend

Felix Deschler
title: How Exciton Interactions Control Spin Depolarisation in Layered Hybrid Perovskites.
venue: Nano letters
year: 2020

abstract: This work demonstrates the strong excitonic magneto optic (MO) effects of magnetic circular dichroism (MCD) and Faraday rotation (FR) in nonmagnetic two dimensional (2D) organic inorganic hybrid Ruddlesden Popper perovskites (RPPs) at room temperature. Due to their strong and sharp excitonic absorption as a result of unique quantum well structures of 2D RPPs, sizeable linear excitonic MO effects of MCD and FR can be observed at room temperature under a low magnetic field <1 T) compared with their three dimensional counterpart. In addition, since the band gaps of 2D organic inorganic hybrid perovskites can be manipulated either by changing the number n of inorganic octahedral slabs per unit cell or through halide engineering, linear excitonic MO effects of 2D RPPs can be observed through the broadband spectral ranges of visible light. Our result may pave the way for the promising research field of MO and magneto optoelectronic applications based on 2D organic inorganic hybrid perovskites with facile solution processes.
author_names: Tzu-Pei Chen

Jun-Xiao Lin

Cheng-Chieh Lin

Chi-Ying Lin

W Ke

Di-Yan Wang

Hua-Shu Hsu

Chia-Chun Chen

Chun-Wei Chen
title: Strong Excitonic Magneto Optic Effects in Two Dimensional Organic Inorganic Hybrid Perovskites.
venue: ACS applied materials interfaces
year: 2021

abstract: The introduction of chirality into organic inorganic hybrid perovskites (OIHPs) is expected to achieve excellent photoelectric and nonlinear materials related to circular dichroism. Chirality dependent circular photogalvanic effect and spin transport have already been studied in OIHPs. However, chirality dependent second harmonic generation (SHG) is rarely studied in bulk single crystal of OIHPs. Due to the existence of asymmetric center and intrinsic chirality in the chiral OIHPs, the different efficiencies of SHG signal occurs when the circularly polarized light (CPL) with different phases passes through the chiral crystal, which is defined as second harmonic generation circular dichroism (SHG CD) Here, the SHG CD effect has been successfully developed in bulk single crystals chiral one dimensional (1D) R S 3 aminopiperidine]PbI 4 which crystallize in a chiral space group P 2 1 2 1 2 1 More importantly, it is the first time to distinguish CPL using chirality dependent SHG CD effect in OIHPs bulk single crystals. Furthermore, such SHG CD technology breaks through the conventional CPL detection using chiral semiconductor, thus extending the detection range to near infrared region (NIR) In this way, the anisotropy factor (g SHG CD through SHG CD signal is as high as 0.21. The results not only expand the applications of chiral OIHPs in nonlinear optics (NLO) field, but also provide a new method to distinguish the CPL in NIR.
author_names: Dongying Fu

Jianli Xin

Xian-Ming Zhang
title: Chirality Dependent Second order Nonlinear Optical Effects in 1D Organic Inorganic Hybrid Perovskites Bulk Single Crystal.
venue: Angewandte Chemie
year: 2021

abstract: An organic inorganic hybrid perovskite incorporating chiral organic molecules is demonstrated as a new class of chiral semiconductors. Chiral perovskites exhibit oppositely signed circular dichroism (CD) according to the S and R configurations of chiral organics. The CD signals can be also varied by changing the crystalline orientation and thickness of the chiral perovskite films.
author_names: Jihoon Ahn

Eun Song Lee

Jeiwan Tan

Wooseok Yang

Bokyung Kim

Jooho Moon
title: A new class of chiral semiconductors: chiral organic molecule incorporating organic inorganic hybrid perovskites
year: 2017

abstract: Chiral perovskites have emerged as a significant class of materials showing promising optoelectronic and spintronic applications. Reports of chiral perovskite ferroelectrics, however, have been scarce. In this work, we have successfully synthesized homochiral lead iodide perovskite ferroelectrics (R) N (1 phenylethyl)ethane 1,2 diaminium]PbI4 and (S) N (1 phenylethyl)ethane 1,2 diaminium]PbI4 by the chemical design of introducing a methyl group into the organic cation of the parent (N benzylethane 1,2 diaminium)PbI4. Vibrational circular dichroism spectra identify the chiral mirroring relationship. They both undergo 222F2 type paraelectric ferroelectric behavior at around 378 K coupled with clear ferroelastic domains "ON/OFF" switching. Besides, they exhibit an evident thermochromism with color change from orange yellow to orange red. To our knowledge, the discovery of integrated ferroelectricity, ferroelasticity and reversible thermochromism in chiral perovskites is unprecedented. This finding offers a resultful path to design chiral perovskite ferroelectrics and is of great inspiration to the discovery of multifunctional perovskite materials.
author_names: Yu-Ling Zeng

Xue-Qin Huang

Chao-Ran Huang

Hua Zhang

Fang Wang

Zhongxia Wang
title: Unprecedented 2D Homochiral Hybrid Lead Iodide Perovskite Thermochromic Ferroelectrics with Ferroelastic Switching.
venue: Angewandte Chemie
year: 2021

abstract: The effect of chemical composition modification on the chiroptical property of chiral organic ammonium cation containing organic inorganic hybrid perovskite (chiral OIHP) is investigated. Varying the mixing ratio of bromide and iodide anions in (S or R C6H5CH2(CH3)NH3)2PbI4(1 x)Br4x modifies the bandgap of chiral OIHP, leading to a shift of the circular dichroism (CD) signal from 495 to 474 nm. However, it is also found that an abrupt crystalline structure transition occurs, and the CD signal is turned off when iodide determinant phases are transformed into the bromide determinant phase. To obtain CD in the wavelength range where the bromide determinant phase is supposed to exhibit chiroptical activity, that is, <474 nm, S or R C12H7CH2(CH3)NH3 with a larger spacer group can be adopted; thus, the CD signal can be further blue shifted to ~375 nm. Here we show that chemical composition modification of chiral OIHP affects the chiroptical properties of chiral OIHP in two ways: 1) tuning the wavelength of CD by modulating the excitonic band structure and 2) switching the CD on and off by inducing a crystalline structure change. These properties can be utilized for structural engineering of high performance chiroptical materials for spin polarized light emitting devices and polarization based optoelectronics.
author_names: Jihoon Ahn

Sunihl Ma

Ji-Young Kim

Jihoon Kyhm

Wooseok Yang

Jung Ah Lim

Nicholas A Kotov

Jooho Moon
title: Chiral 2D Organic Inorganic Hybrid Perovskite with Circular Dichroism Tunable Over Wide Wavelength Range.
venue: Journal of the American Chemical Society
year: 2020

abstract: We demonstrate theoretically that non chiral perovskite layers can exhibit circular dichroism (CD) in the absence of a magnetic field and without chiral activation by chiral molecules. The effect is shown to be due to splitting of helical excitonic states which can form in structures of orthorhombic or lower symmetry that exhibit Rashba spin effects. The selective coupling of these helical exciton states to helical light is shown to give rise to circular dichroism. Polarization dependent absorption is shown to occur due to the combined effect of Rashba splitting, in plane symmetry breaking, and the effect of the exciton momentum on its fine structure, which takes the form of Zeeman splitting in an effective magnetic field. This phenomenon, which can be considered as a manifestation of extrinsic chirality, results in significant CD with an anisotropy factor of up to 30% in orthorhombic perovskite layers under off normal, top illumination conditions, raising the possibility of its observation in non chiral perovskite structures.
author_names: Peter C Sercel

Zeev Valy Vardeny

Alexander L Efros
title: Circular dichroism in non chiral metal halide perovskites.
venue: Nanoscale
year: 2020