Tin Oxynitride-based Ferroelectric Semiconductors for Solar Energy Conversion Applications

Band Gaps ◽

Polar Phase ◽

Carrier Effective Mass ◽

Halide Perovskites ◽

Lead-halide perovskites have emerged as a promising class of semiconductors; however they suffer from issues related to lead-toxicity and instability. We report results of a firstprinciples-based design of heavy-metal-based oxynitrides as alternatives to lead-halide perovskites. We have used density-functional-theory calculations to search a vast composition space of ABO2N and ABON2 compounds, where B is a p-block cation, and A is an alkaline, alkaliearth, rare-earth or transition metal cation, and identify 10 new ABO2N oxynitride semiconductors that we expect to be formable. Specifically, we discover a new family of ferroelectric semiconductors with A3+SnO2N stoichiometry (A = Y, Eu, La, In, and Sc) in the LuMnO3-type structure, which combine the strong bonding of metal oxides with the low carrier effective mass and small, tunable band gaps of the lead-halide perovskites. These tin oxynitrides have predicted direct band gaps ranging from 1.6 – 3.3 eV, and a sizeable electric polarization up to 17 μC/cm2 , which is predicted to be switchable by an external electric field through a non-polar phase. With their unique combination of polarization, low carrier effective mass and band gaps spanning the entire visible spectrum, we expect ASnO2N ferroelectric semiconductors will find useful applications as photovoltaics, photocatalysts, and for optoelectronics.

Ab initio modeling of band gaps of cesium lead halide perovskites depending on the dopant amount

Journal of Physics Conference Series ◽

10.1088/1742-6596/1096/1/012115 ◽

2018 ◽

Vol 1096 ◽

pp. 012115 ◽

Cited By ~ 1

Author(s):

V A Saleev ◽

A V Shipilova

Keyword(s):

Ab Initio ◽

Band Gaps ◽

Ab Initio Modeling ◽

Halide Perovskites ◽

Dynamical properties of organo lead-halide perovskites and their interfaces to titania: insights from Density Functional Theory

Heliyon ◽

10.1016/j.heliyon.2020.e03427 ◽

2020 ◽

Vol 6 (3) ◽

pp. e03427

Author(s):

Niall J. English

Keyword(s):

Density Functional Theory ◽

Density Functional ◽

Functional Theory ◽

Halide Perovskites ◽

Dynamical Properties ◽

First-Principle Study of the Structural, Electronic, and Optical Properties of Cubic Cesium Lead Halide Perovskites for Photovoltaic System

Scientific Inquiry and Review ◽

10.32350/sir/2020/42/977 ◽

2020 ◽

Vol 4 (2) ◽

pp. 1-16

Author(s):

Muhammad Waqas

Keyword(s):

Optical Properties ◽

Band Gap ◽

Density Functional ◽

Covalent Bond ◽

Wide Band ◽

Photovoltaic System ◽

Full Potential ◽

Potential Applications ◽

Halide Perovskites ◽

Lead halide perovskites have attracted considerable attention as optoelectronic materials because these materials have high photovoltaic conversion efficiency. The current study is based on Density Functional Theory (DFT). This theory was used to calculate the structural, optical, and electronic properties of the lead halide perovskites CsPbX3 (X = Chlorine (Cl), Bromine (Br), Iodine (I)) compounds . In order to calculate the above mentioned properties of cubic perovskites CsPbX3 (X = Cl, Br, I), Full Potential Linear Augmented Plane Wave (FP-LAPW) method was implemented in conjunction with DFT utilizing LDA, GGA-PBE and mBJ approximations. A good agreement was found between experimentally measured values and theoretically calculated lattice constants. These compounds have a direct and wide band gap located at the point of R-symmetry, while the band gap decreases from ‘Cl’ to ‘I’ down the group. The densities of electrons revealed a strong ionic bond between Cs and halides and a strong covalent bond between ‘Pb’ and (Cl, Br, and I). The dielectric functions (reflectivity, refractive indices, absorption coefficients), optical conductivities (real and imaginary part) and other optical properties indicated that these compounds have novel energy harvester applications. The modeling of these perovskite compounds shows that they have high absorption power and direct band gaps in visible ultraviolet range and it also shows that these compounds have potential applications in solar cells.

Lock-and-Key Exciplexes for Thermally Activated Delayed Fluorescence

Organic Materials ◽

10.1055/s-0039-3402059 ◽

2020 ◽

Vol 02 (01) ◽

pp. 001-010

Author(s):

Constantin-Christian A. Voll ◽

Georgios Markopoulos ◽

Tony C. Wu ◽

Matthew Welborn ◽

Jens U. Engelhart ◽

...

Keyword(s):

Density Functional ◽

Materials Science ◽

Visible Spectrum ◽

Delayed Fluorescence ◽

Thermally Activated Delayed Fluorescence ◽

Light Emitting Devices ◽

Thermally Activated ◽

Emission Color ◽

Exciplex Emission

We combine synthetic supramolecular chemistry and materials science to develop novel exciplexes for thermally activated delayed fluorescence. Our approach starts from a bowl-shaped acceptor molecule for which we synthesize tailor-made donors that bind in a lock-and-key fashion. The donor design is guided by extensive density functional theory calculations of three independent donor families. The investigation of a large number of custom-synthesized donors allows us to derive empirical relationships for the prediction of the exciplex emission color. Incorporated within organic light-emitting devices, the lock-and-key exciplexes yield external quantum efficiencies of up to 5.4%, with potentially tunable emission color across the blue and green visible spectrum.

Electronic and optical properties of bulk and surface of CsPbBr3 inorganic halide perovskite a first principles DFT 1/2 approach

Scientific Reports ◽

10.1038/s41598-021-99551-y ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Mohammed Ezzeldien ◽

Samah Al-Qaisi ◽

Z. A. Alrowaili ◽

Meshal Alzaid ◽

E. Maskar ◽

...

Keyword(s):

Optical Properties ◽

Band Gap ◽

Visible Spectrum ◽

Ultra Violet ◽

Electronic And Optical Properties ◽

Direct Band ◽

Halide Perovskites ◽

Electro Magnetic ◽

Experimental Findings ◽

AbstractThis work aims to test the effectiveness of newly developed DFT-1/2 functional in calculating the electronic and optical properties of inorganic lead halide perovskites CsPbBr3. Herein, from DFT-1/2 we have obtained the direct band gap of 2.36 eV and 3.82 eV for orthorhombic bulk and 001-surface, respectively. The calculated energy band gap is in qualitative agreement with the experimental findings. The bandgap of ultra-thin film of CsPbBr3 is found to be 3.82 eV, which is more than the expected range 1.23-3.10 eV. However, we have found that the bandgap can be reduced by increasing the surface thickness. Thus, the system under investigation looks promising for optoelectronic and photocatalysis applications, due to the bandgap matching and high optical absorption in UV–Vis (Ultra violet and visible spectrum) range of electro-magnetic(em) radiation.

Contrasting 1D tunnel-structured and 2D layered polymorphs of V2O5: relating crystal structure and bonding to band gaps and electronic structure

Physical Chemistry Chemical Physics ◽

10.1039/c6cp02096h ◽

2016 ◽

Vol 18 (23) ◽

pp. 15798-15806 ◽

Cited By ~ 23

Author(s):

Thomas M. Tolhurst ◽

Brett Leedahl ◽

Justin L. Andrews ◽

Peter M. Marley ◽

Sarbajit Banerjee ◽

...

Keyword(s):

Crystal Structure ◽

Density Functional Theory ◽

Density Functional ◽

Band Gaps ◽

Structure Property ◽

Functional Theory ◽

X Ray ◽

Structure Property Relationships ◽

Structure And Bonding

An elucidation of structure–property relationships in V2O5 polymorphs using synchrotron X-ray spectroscopy and density functional theory calculations.

A band-gap database for semiconducting inorganic materials calculated with hybrid functional

Scientific Data ◽

10.1038/s41597-020-00723-8 ◽

2020 ◽

Vol 7 (1) ◽

Author(s):

Sangtae Kim ◽

Miso Lee ◽

Changho Hong ◽

Youngchae Yoon ◽

Hyungmin An ◽

...

Keyword(s):

Band Gap ◽

Density Functional ◽

Magnetic Ordering ◽

Inorganic Materials ◽

Band Gaps ◽

Device Performance ◽

Photovoltaic Devices ◽

Hybrid Functional ◽

Functional Theory

Abstract Semiconducting inorganic materials with band gaps ranging between 0 and 5 eV constitute major components in electronic, optoelectronic and photovoltaic devices. Since the band gap is a primary material property that affects the device performance, large band-gap databases are useful in selecting optimal materials in each application. While there exist several band-gap databases that are theoretically compiled by density-functional-theory calculations, they suffer from computational limitations such as band-gap underestimation and metastable magnetism. In this data descriptor, we present a computational database of band gaps for 10,481 materials compiled by applying a hybrid functional and considering the stable magnetic ordering. For benchmark materials, the root-mean-square error in reference to experimental data is 0.36 eV, significantly smaller than 0.75–1.05 eV in the existing databases. Furthermore, we identify many small-gap materials that are misclassified as metals in other databases. By providing accurate band gaps, the present database will be useful in screening materials in diverse applications.

Electronic structure, effective mass, and optical dispersion of 2-mercapto-5-methyl-1,3,4-thiadiazole: density functional theory calculations

Materials Science in Semiconductor Processing ◽

10.1016/j.mssp.2014.05.054 ◽

2014 ◽

Vol 26 ◽

pp. 649-656 ◽

Cited By ~ 6

Author(s):

Sikander Azam ◽

A.H. Reshak

Keyword(s):

Density Functional Theory ◽

Electronic Structure ◽

Effective Mass ◽

Density Functional ◽

Functional Theory ◽

Optical Dispersion

Structural and electronic properties of oligo- and polythiophenes modified by substituents

Beilstein Journal of Nanotechnology ◽

10.3762/bjnano.3.101 ◽

2012 ◽

Vol 3 ◽

pp. 909-919 ◽

Cited By ~ 26

Author(s):

Simon P Rittmeyer ◽

Axel Groß

Keyword(s):

Electronic Properties ◽

Density Functional ◽

Electronic Devices ◽

Electronic And Structural Properties

Building Blocks ◽

Band Gaps ◽

Molecular Electronic ◽

Functional Theory ◽

Structural And Electronic Properties ◽

The electronic and structural properties of oligo- and polythiophenes that can be used as building blocks for molecular electronic devices have been studied by using periodic density functional theory calculations. We have in particular focused on the effect of substituents on the electronic structure of thiophenes. Whereas singly bonded substituents, such as methyl, amino or nitro groups, change the electronic properties of thiophene monomers and dimers, they hardly influence the band gap of polythiophene. In contrast, phenyl-substituted polythiophenes as well as vinyl-bridged polythiophene derivatives exhibit drastically modified band gaps. These effects cannot be explained by simple electron removal or addition, as calculations for charged polythiophenes demonstrate.