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Molecular Spectroscopy for Applications in Material Science: Hybrid Organic–Inorganic Perovskites and Related Compounds

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A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Materials Chemistry".

Deadline for manuscript submissions: closed (31 March 2023) | Viewed by 29687

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Prof. Dr. Mirosław Mączka

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Wlodzimierz Trzebiatowski Institute of Low Temperature and Structure Research of the Polish Academy of Sciences, Wroclaw, Poland
Interests: organic–inorganic hybrid materials; metal–organic frameworks; coordination polymers; ferroelectrics; multiferroics; optoelectronic materials; IR; Raman; optical properties
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Dr. Maciej Ptak

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Wlodzimierz Trzebiatowski Institute of Low Temperature and Structure Research of the Polish Academy of Sciences, Wroclaw, Poland
Interests: metal–organic frameworks; coordination polymers; inorganic compounds; ferroelectrics; optical materials; IR; Raman; optical properties

Special Issue Information

Dear Colleagues,

Hybrid organic–inorganic compounds have been the subject of intense studies because their diverse structural and chemical variability offers unlimited opportunities for tuning their physical and chemical properties by chemical modification of organic and/or inorganic parts. One of the most important sub-groups of organic–inorganic hybrid materials are metal halides, particularly lead halide and lead-free perovskites, which have proven to be a fascinating class of semiconductors possessing excellent optoelectronic properties.

Understanding the optical properties of these materials requires the application of emission and electron absorption spectroscopic methods. However, luminescent and optoelectronic properties of hybrid materials are also strongly influenced by the lattice dynamics. Furthermore, the dynamics of the organic cations plays a major role in phase transitions and the appearance of useful properties such as ferroelectricity or nonlinear optical properties. It is, therefore, of great interest to perform studies of hybrid organic–inorganic materials, especially those undergoing order–disorder phase transitions, using various spectroscopic methods that have different probing length scales and sensitivities.

This Special Issue aims to act as a forum for the dissemination of the latest information on the application of spectroscopic methods (e.g., optical, Raman, IR, terahertz, NMR, EPR, and dielectric) in studies of hybrid organic–inorganic compounds including lead halides and lead-free perovskites. We encourage authors to submit manuscripts in the form of a research paper, review, or communication. All aspects embracing the structural, luminescent, optical and dielectric properties as well as phase transition mechanism, lattice dynamics and electron–phonon coupling will be covered.

Prof. Mirosław Mączka
Dr. Maciej Ptak
Guest Editors

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Keywords

Perovskites
hybrid organic-inorganic materials
metal-organic frameworks
halides
optoelectronic materials
spectroscopy
lattice dynamics
photoluminescence
dielectric properties
Raman
IR
NMR
EPR
THz

Published Papers (10 papers)

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Research

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15 pages, 3948 KiB

Open AccessArticle

Structural, Electric and Dynamic Properties of (Pyrrolidinium)₃[Bi₂I₉] and (Pyrrolidinium)₃[Sb₂I₉]: New Lead-Free, Organic–Inorganic Hybrids with Narrow Band Gaps

by Magdalena Rowińska, Anna Piecha-Bisiorek, Wojciech Medycki, Piotr Durlak, Ryszard Jakubas and Anna Gagor

Molecules 2023, 28(9), 3894; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules28093894 - 05 May 2023

Cited by 3 | Viewed by 1519

Abstract

Hybrid organic–inorganic iodides based on Bi(III) and Sb(III) provide integrated functionalities through the combination of high dielectric constants, semiconducting properties and ferroic phases. Here, we report a pyrrolidinium-based bismuth (1) and antimony (2) iodides of (NC₄H₁₀)₃[M₂I₉] (M: Bi(III), Sb(III)) formula which are ferroelastic at room temperature. The narrow band gaps (~2.12 eV for 1 and 2.19 eV for 2) and DOS calculations indicate the semiconducting characteristics of both materials. The crystal structure consists of discrete, face-sharing bioctahedra [M₂I₉]³⁻ and disordered pyrrolidinium amines providing charge balance and acting as spacers between inorganic moieties. At room temperature, 1 and 2 accommodate orthorhombic Cmcm symmetry. 1 displays a complex temperature-induced polymorphism. It is stable up to 525 K and undergoes a sequence of low-temperature phase transitions (PTs) at 221/222 K (I ↔ II) and 189/190 K (II ↔ III) and at 131 K (IV→III), associated with the ordering of pyrrolidinium cations and resulting in Cmcm symmetry breaking. 2 undergoes only one PT at T = 215 K. The dielectric studies disclose a relaxation process in the kilohertz frequency region, assigned to the dynamics of organic cations, described well by the Cole–Cole relation. A combination of single-crystal X-ray diffraction, synchrotron powder diffraction, spin–lattice relaxation time of ¹H NMR, dielectric and calorimetric studies is used to determine the structural phase diagram, cation dynamics and electric properties of (NC₄H₁₀)₃[M₂I₉]_. Full article

(This article belongs to the Special Issue Molecular Spectroscopy for Applications in Material Science: Hybrid Organic–Inorganic Perovskites and Related Compounds)

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13 pages, 1088 KiB

Open AccessArticle

Probing Methyl Group Tunneling in [(CH₃)₂NH₂][Zn(HCOO)₃] Hybrid Perovskite Using Co²⁺ EPR

by Gediminas Usevičius, Andrea Eggeling, Ignas Pocius, Vidmantas Kalendra, Daniel Klose, Mirosław Mączka, Andreas Pöppl, Jūras Banys, Gunnar Jeschke and Mantas Šimėnas

Molecules 2023, 28(3), 979; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules28030979 - 18 Jan 2023

Cited by 4 | Viewed by 1807

Abstract

At low temperature, methyl groups act as hindered quantum rotors exhibiting rotational quantum tunneling, which is highly sensitive to a local methyl group environment. Recently, we observed this effect using pulsed electron paramagnetic resonance (EPR) in two dimethylammonium-containing hybrid perovskites doped with paramagnetic Mn²⁺ ions. Here, we investigate the feasibility of using an alternative fast-relaxing Co²⁺ paramagnetic center to study the methyl group tunneling, and, as a model compound, we use dimethylammonium zinc formate [(CH₃)₂NH₂][Zn(HCOO)₃] hybrid perovskite. Our multifrequency (X-, Q- and W-band) EPR experiments reveal a high-spin state of the incorporated Co²⁺ center, which exhibits fast spin-lattice relaxation and electron spin decoherence. Our pulsed EPR experiments reveal magnetic field independent electron spin echo envelope modulation (ESEEM) signals, which are assigned to the methyl group tunneling. We use density operator simulations to extract the tunnel frequency of 1.84 MHz from the experimental data, which is then used to calculate the rotational barrier of the methyl groups. We compare our results with the previously reported Mn²⁺ case showing that our approach can detect very small changes in the local methyl group environment in hybrid perovskites and related materials. Full article

(This article belongs to the Special Issue Molecular Spectroscopy for Applications in Material Science: Hybrid Organic–Inorganic Perovskites and Related Compounds)

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13 pages, 4234 KiB

Open AccessArticle

Hybrid Chlorides with Methylhydrazinium Cation: [CH₃NH₂NH₂]CdCl₃ and Jahn-Teller Distorted [CH₃NH₂NH₂]CuCl₃

by Jan A. Zienkiewicz, Dorota A. Kowalska, Dawid Drozdowski, Adam Pikul and Maciej Ptak

Molecules 2023, 28(2), 473; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules28020473 - 04 Jan 2023

Cited by 1 | Viewed by 1392

Abstract

The synthesis, structural, phonon, optical, and magnetic properties of two hybrid organic-inorganic chlorides with monoprotonated methylhydrazinium cations (CH₃NH₂NH₂⁺, MHy⁺), [CH₃NH₂NH₂]CdCl₃ (MHyCdCl₃), and [CH₃NH₂NH₂]CuCl₃ (MHyCuCl₃), are reported. In contrast to previously reported MHyM^IICl₃ (M^II = Mn²⁺, Ni²⁺, and Co²⁺) analogues, neither compound undergoes phase transitions. The MHyCuCl₃ has a crystal structure familiar to previous crystals composed of edge-shared 1D chains of the [CuCl₅N] octahedra. MHyCuCl₃ crystallizes in monoclinic P2₁/c symmetry with MHy⁺ cations directly linked to the Cu²⁺ ions. The MHyCdCl₃ analogue crystallizes in lower triclinic symmetry with zig-zag chains of the edge-shared [CdCl₆] octahedra. The absence of phase transitions is investigated and discussed. It is connected with slightly stronger hydrogen bonding between cations and the copper–chloride chains in MHyCuCl₃ due to the strong Jahn–Teller effect causing the octahedra to elongate, resulting in a better fit of cations in the accessible space between chains. The absence of structural transformation in MHyCdCl₃ is due to intermolecular hydrogen bonding between two neighboring MHy⁺ cations, which has never been reported for MHy⁺-based hybrid halides. Optical investigations revealed that the bandgaps in Cu²⁺ and Cd²⁺ analogues are 2.62 and 5.57 eV, respectively. Magnetic tests indicated that MHyCuCl₃ has smeared antiferromagnetic ordering at 4.8 K. Full article

(This article belongs to the Special Issue Molecular Spectroscopy for Applications in Material Science: Hybrid Organic–Inorganic Perovskites and Related Compounds)

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8 pages, 1466 KiB

Open AccessArticle

Diffuse Reflectance Spectroscopy with Dilution: A Powerful Method for Halide Perovskites Study

by Aleksei O. Murzin, Anna Yu. Samsonova, Constantinos C. Stoumpos, Nikita I. Selivanov, Alexei V. Emeline and Yury V. Kapitonov

Molecules 2023, 28(1), 350; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules28010350 - 01 Jan 2023

Cited by 3 | Viewed by 1659

Abstract

Halide perovskites and their low-dimensional analogs are promising semiconductor materials for solar cells, LEDs, lasers, detectors and other applications in the area of photonics. The most informative optical property of semiconductor photonics materials is the absorption spectrum enabling observation of the fundamental absorption edge, exciton structure, defect-related bands, etc. Traditionally, in the study of halide perovskites, this spectrum is obtained by absorption spectroscopy of thin films or diffuse reflectance spectroscopy of powders. The first method is applicable only to compounds with the developed thin film deposition technology, and in the second case, a large absorption coefficient narrows the observations down to the sample transparency region. In this paper, we suggest the diffuse reflectance spectroscopy with dilution as a method for obtaining the full-range absorption spectrum from halide perovskite powders, and demonstrate its application to practically important cases. Full article

(This article belongs to the Special Issue Molecular Spectroscopy for Applications in Material Science: Hybrid Organic–Inorganic Perovskites and Related Compounds)

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10 pages, 1659 KiB

Open AccessArticle

Vibrational Properties and DFT Calculations of Perovskite-Type Methylhydrazinium Manganese Hypophosphite

by Aneta Ciupa-Litwa, Maciej Ptak, Edyta Kucharska, Jerzy Hanuza and Mirosław Mączka

Molecules 2020, 25(21), 5215; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules25215215 - 09 Nov 2020

Cited by 13 | Viewed by 2697

Abstract

Recently discovered hybrid perovskites based on hypophosphite ligands are a promising class of compounds exhibiting unusual structural properties and providing opportunities for construction of novel functional materials. Here, we report for the first time the detailed studies of phonon properties of manganese hypophosphite templated with methylhydrazinium cations ([CH₃NH₂NH₂][Mn(H₂PO₂)₃]). Its room temperature vibrational spectra were recorded for both polycrystalline sample and a single crystal. The proposed assignment based on Density Functional Theory (DFT) calculations of the observed vibrational modes is also presented. It is worth noting this is first report on polarized Raman measurements in this class of hybrid perovskites. Full article

(This article belongs to the Special Issue Molecular Spectroscopy for Applications in Material Science: Hybrid Organic–Inorganic Perovskites and Related Compounds)

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16 pages, 4603 KiB

Open AccessArticle

Raman Spectroscopy Studies on the Barocaloric Hybrid Perovskite [(CH₃)₄N][Cd(N₃)₃]

by Rosivaldo Xavier da Silva, Carlos William de Araujo Paschoal, Clenilton Costa dos Santos, Alberto García-Fernández, Jorge Salgado-Beceiro, María Antonia Señarís-Rodríguez, Manuel Sanchez-Andujar and Ariel Nonato Almeida de Abreu Silva

Molecules 2020, 25(20), 4754; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules25204754 - 16 Oct 2020

Cited by 7 | Viewed by 2792

Abstract

Temperature-dependent Raman scattering and differential scanning calorimetry were applied to the study of the hybrid organic-inorganic azide-perovskite [(CH₃)₄N][Cd(N₃)₃], a compound with multiple structural phase transitions as a function of temperature. A significant entropy variation was observed associated to such phase transitions, |∆S| ~ 62.09 J·kg⁻¹ K⁻¹, together with both a positive high barocaloric (BC) coefficient |δT_t/δP| ~ 12.39 K kbar⁻¹ and an inverse barocaloric (BC) coefficient |δT_t/δP| ~ −6.52 kbar⁻¹, features that render this compound interesting for barocaloric applications. As for the obtained Raman spectra, they revealed that molecular vibrations associated to the NC_4, N₃^– and CH₃ molecular groups exhibit clear anomalies during the phase transitions, which include splits and discontinuity in the phonon wavenumber and lifetime. Furthermore, variation of the TMA⁺ and N₃^– modes with temperature revealed that while some modes follow the conventional red shift upon heating, others exhibit an unconventional blue shift, a result which was related to the weakening of the intermolecular interactions between the TMA (tetramethylammonium) cations and the azide ligands and the concomitant strengthening of the intramolecular bondings. Therefore, these studies show that Raman spectroscopy is a powerful tool to gain information about phase transitions, structures and intermolecular interactions between the A-cation and the framework, even in complex hybrid organic-inorganic perovskites with highly disordered phases. Full article

(This article belongs to the Special Issue Molecular Spectroscopy for Applications in Material Science: Hybrid Organic–Inorganic Perovskites and Related Compounds)

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10 pages, 2081 KiB

Open AccessFeature PaperArticle

Changes in the Electrical Characteristics of Perovskite Solar Cells with Aging Time

by Apurba Mahapatra, Nishi Parikh, Pawan Kumar, Manoj Kumar, Daniel Prochowicz, Abul Kalam, Mohammad Mahdi Tavakoli and Pankaj Yadav

Molecules 2020, 25(10), 2299; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules25102299 - 14 May 2020

Cited by 31 | Viewed by 4380

Abstract

The last decade has witnessed the impressive progress of perovskite solar cells (PSCs), with power conversion efficiency exceeding 25%. Nevertheless, the unsatisfactory device stability and current–voltage hysteresis normally observed with most PSCs under operational conditions are bottlenecks that hamper their further commercialization. Understanding the electrical characteristics of the device during the aging process is important for the design and development of effective strategies for the fabrication of stable PSCs. Herein, electrochemical impedance spectroscopical (IS) analyses are used to study the time-dependent electrical characteristics of PSC. We demonstrate that both the dark and light ideality factors are sensitive to aging time, indicating the dominant existence of trap-assisted recombination in the investigated device. By analyzing the capacitance versus frequency responses, we show that the low-frequency capacitance increases with increasing aging time due to the accumulation of charges or ions at the interfaces. These results are correlated with the observed hysteresis during the current–voltage measurement and provide an in-depth understanding of the degradation mechanism of PSCs with aging time. Full article

(This article belongs to the Special Issue Molecular Spectroscopy for Applications in Material Science: Hybrid Organic–Inorganic Perovskites and Related Compounds)

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11 pages, 1714 KiB

Open AccessArticle

Dielectric Spectroscopy of Water Dynamics in Functionalized UiO-66 Metal-Organic Frameworks

by Sergejus Balčiūnas, Diana Pavlovaitė, Martynas Kinka, Jyun-Yi Yeh, Po-Chun Han, Fa-Kuen Shieh, Kevin C.-W. Wu, Mantas Šimėnas, Robertas Grigalaitis and Jūras Banys

Molecules 2020, 25(8), 1962; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules25081962 - 23 Apr 2020

Cited by 9 | Viewed by 3398

Abstract

We present a dielectric spectroscopy study of dipolar dynamics in the hydrated UiO-66(Zr) type metal-organic frameworks (MOFs) functionalized with −NH₂ and −F groups. Experiments are performed in a broad temperature and frequency ranges allowing us to probe several dipolar relaxations. For both samples at temperature below 220 K, we observe confined supercooled water dynamics, which can be described by the Arrhenius law. At slightly higher temperature, a second less pronounced dipolar relaxation is identified, and its origin is discussed. At even higher temperature, the dielectric permittivity exhibits anomalous increase with increasing temperature due to the proton conductivity. Upon further heating, the permittivity shows a sudden decrease indicating a reversible removal of water molecules. Measurements of the dehydrated samples reveal absence of all three dipolar processes. Full article

(This article belongs to the Special Issue Molecular Spectroscopy for Applications in Material Science: Hybrid Organic–Inorganic Perovskites and Related Compounds)

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11 pages, 2465 KiB

Open AccessArticle

Photoluminescent Spectral Broadening of Lead Halide Perovskite Nanocrystals Investigated by Emission Wavelength Dependent Lifetime

by Jinlei Zhang, Jiuyang He, Lun Yang and Zhixing Gan

Molecules 2020, 25(5), 1151; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules25051151 - 04 Mar 2020

Cited by 8 | Viewed by 3376

Abstract

Despite intensive efforts, the fluorescence of perovskite nanocrystals (NCs) still suffers from a poor color purity, which limits the applications in light emitting and multicolor display. A deep understanding on the fundamental of the photoluminescent (PL) spectral broadening is thus of great significance. Herein, the PL decay curves of the CsPbCl_xBr_3-x NCs are monitored at different wavelengths covering the entire PL band. Moreover, energy relaxation time τ and radiative recombination time β are obtained by numerical fittings. The dependences of τ and 1/β on the detection wavelength agree well with the steady-state PL spectrum, indicating the observed PL broadening is an intrinsic effect due to the resonance and off-resonance exciton radiative recombination processes. This work not only provides a new analysis method for time-resolved PL spectra of perovskites, but also gains a deep insight into the spectral broadening of the lead halide perovskite NCs. Full article

(This article belongs to the Special Issue Molecular Spectroscopy for Applications in Material Science: Hybrid Organic–Inorganic Perovskites and Related Compounds)

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Review

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40 pages, 7565 KiB

Open AccessReview

A Review on Lead-Free Hybrid Halide Perovskites as Light Absorbers for Photovoltaic Applications Based on Their Structural, Optical, and Morphological Properties

by Shadrack J. Adjogri and Edson L. Meyer

Molecules 2020, 25(21), 5039; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules25215039 - 30 Oct 2020

Cited by 22 | Viewed by 5504

Abstract

Despite the advancement made by the scientific community in the evolving photovoltaic technologies, including the achievement of a 29.1% power conversion efficiency of perovskite solar cells over the past two decades, there are still numerous challenges facing the advancement of lead-based halide perovskite absorbers for perovskite photovoltaic applications. Among the numerous challenges, the major concern is centered around the toxicity of the emerging lead-based halide perovskite absorbers, thereby leading to drawbacks for their pragmatic application and commercialization. Hence, the replacement of lead in the perovskite material with non-hazardous metal has become the central focus for the actualization of hybrid perovskite technology. This review focuses on lead-free hybrid halide perovskites as light absorbers with emphasis on how their chemical compositions influence optical properties, morphological properties, and to a certain extent, the stability of these perovskite materials. Full article

(This article belongs to the Special Issue Molecular Spectroscopy for Applications in Material Science: Hybrid Organic–Inorganic Perovskites and Related Compounds)

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