Comparative Performance Analysis of MAPbI3 and FAPbI3 Perovskites: Study of Optoelectronic Properties and Stability

The exploitation of fossil resources to meet humanity’s energy needs is the root cause of the climate warming phenomenon facing the planet. In this context, non-carbon-based energies, such as photovoltaic energy, are identified as crucial solutions. Organic perovskites MAPbI3 and FAPbI3, characterized by their abundance, low cost, and ease of synthesis, are emerging as candidates for study to enhance their competitiveness. It is within this framework that this article presents a comparative analysis of the performances of MAPbI3 and FAPbI3 perovskites in the context of photovoltaic devices. The analysis focuses on the optoelectronic characteristics and stability of these high-potential materials. The optical properties of perovskites are rigorously evaluated, including band gaps, photoluminescence, and light absorption, using UV-Vis spectroscopy and photoluminescence techniques. The crystal structure is characterized by X-ray diffraction, while film morphology is examined through scanning electron microscopy. The results reveal significant variations between the two types of perovskites, directly impacting the performance of resulting solar devices. Simultaneously, the stability of perovskites is subjected to a thorough study, exposing the materials to various environmental conditions, highlighting key determinants of their durability. Films of MAPbI3 and FAPbI3 demonstrate distinct differences in terms of topography, optical performance, and stability. Research has unveiled that planar perovskite solar cells based on FAPbI3 offer higher photoelectric conversion efficiency, surpassing their MAPbI3-based counterparts in terms of performance. These advancements aim to overcome stability constraints and enhance the long-term durability of perovskites, ultimately aiming for practical application of these materials. This comprehensive comparative analysis provides an enlightened understanding of the optoelectronic performance and stability of MAPbI3 and FAPbI3 perovskites, which is critically important to guide future research and development of solar devices that are both more efficient and sustainable.

Theoretical Study on the Structural and Optoelectronic Properties of the Linear Perfluorooctane Sulfonate (PFOS)

The perfluoroalkyl substances（PFS） have attracted considerable attention in recent years as a persistent global pollutant to be able to bioaccumulate in higher organisms.In this paper,theoretical analysis on electronic structures,optoelectronic properties and absorption spectra properties of the perflurooctane sulfonate（PFOS） in gas phase have been investigated by using the DFT/TD-DFT method.The geometric structures,electrostatic potentials,energy gaps,ionization potentials,electron affinities,frontier molecular orbital,excitation energies and absorption spectra for the ground state of PFOS were calculated.The result indicates that the ability of accepting electron of neutral PFOS is larger than that of anionic PFOS,while the electron excited by UV irradiation from HOMO to LUMO in the anionic PFOS is easier than that in the neutral PFOS.

Investigation of optoelectronic properties of pure and Co substituted α-Al_2O_3 by Hubbard and modified Becke–Johnson exchange potentials

Advanced GGA ＋ U（Hubbard） and modified Becke–Johnson（mBJ） techniques are used for the calculation of the structural, electronic, and optical parameters of α-Al2-x CoxO3（x = 0.0, 0.167） compounds. The direct band gaps calculated by GGA and m BJ for pure alumina are 6.3 eV and 8.5 eV, respectively. The m BJ approximation provides results very close to the experimental one（8.7 eV）. The substitution of Al with Co reduces the band gap of alumina. The wide and direct band gap of the doped alumina predicts that it can efficiently be used in optoelectronic devices. The optical properties of the compounds like dielectric functions and energy loss function are also calculated. The rhombohedral structure of theα-Al2-x CoxO3（x = 0.0, 0.167） compounds reveal the birefringence properties.

Effect of Back Diffusion of Mg Dopants on Optoelectronic Properties of InGaN-Based Green Light-Emitting Diodes

The effect of back-diffusion of Mg dopants on optoelectronic characteristics of InGaN-based green light-emitting diodes （LEDs） is investigated. The LEDs with less Mg back-diffusion show blue shifts of longer wavelengths and larger wavelengths with the increasing current, which results from the Mg-dopant-related polarization screening. The LEDs show enhanced efficiency with the decreasing Mg back-diffusion in the lower current region. Light outputs follow the power law L α I^m, with smaller parameter m in the LEDs with less Mg back-diffusion, indicating a lower density of trap states. The trap-assisted tunneling current is also suppressed by reducing Mg- defect-related nonradiative centers in the active region. Furthermore, the forward current-voltage characteristics are improved.

Elastic and Optoelectronic Properties of KCdF3:ab initio Calculations through LDA/GGA/TB-mBJ within FP-LAPW Method

Ab initio calculations are performed on the electronic, structural, elastic and optical properties of the cubic per- ovskite KCdF3. Tile Kohn Sham equations are solved by applying the full potential linearized augmented plane wave （FP-LAPW） method. The exchange correlation effects are included through the local density approximation （LDA ）, generalized gradient approximation （GGA） and modified Becke-Johnson （mBJ） exchange potential The calculated lattice constant is in good agreement with the experimental result. The elastic properties such as elastic constants, anisotropy factor, shear modulus, Young＇s modulus and Poisson＇s ratio are calculated. KCdF3 is ductile and elastically anisotropic. The calculations of the electronic band structure, density of states （DOS） and charge density show that this compound has an indirect energy band gap （M-F） with a mixed ionic and covalent bonding. The contribution of the different bands is analyzed from the total and partial density of states curves. Optical response of the dielectric functions, optical reflectivity, absorption coefficient, real part of optical conductivity, refractive index, extinction coefficient and electron energy loss, are presented for the energy range of O-40eV. The compound KCdF3 can be used for high-frequency optical and optoelectronic devices.

Pressure-induced enhancement of optoelectronic properties in PtS2

PtS2, which is one of the group-10 transition metal dichalcogenides, attracts increasing attention due to its extraordinary properties under external modulations as predicted by theory, such as tunable bandgap and indirect-to-direct gap transition under strain; however, these properties have not been verified experimentally. Here we report the first experimental exploration of its optoelectronic properties under external pressure. We find that the photocurrent is weakly pressuredependent below 3 GPa but increases significantly in the pressure range of 3 GPa–4 GPa, with a maximum ～ 6 times higher than that at ambient pressure. X-ray diffraction data shows that no structural phase transition can be observed up to26.8 GPa, which indicates a stable lattice structure of PtS2 under high pressure. This is further supported by our Raman measurements with an observation of linear blue-shifts of the two Raman-active modes to 6.4 GPa. The pressure-enhanced photocurrent is related to the indirect-to-direct/quasi-direct bandgap transition under pressure, resembling the gap behavior under compression strain as predicted theoretically.

Electrical characteristics and optoelectronic properties of metal-semiconductor-metal structure with zinc oxide nanowires across Au electrodes

This paper reports on a method of assembling semiconducting ZnO nanowires onto a pair of Au electrodes to construct a metal--semiconductor metal （MSM） structure by dieleetrophoresis and studying on its electrical characteristics by using current-voltage （Ⅰ - Ⅴ） measurements. An electronic model with two back to back Sehottky diodes in series with a semiconductor of nanowires was established to study the electrical transport of the MSM structures. By fitting the measured Ⅰ - Ⅴ characteristics using the proposed model, the parameters of the Schottky contacts and the resistance of nanowires could be acquired. The photoelectric properties of the MSM structures were also investigated by analysing the measurements of the electrical transports under various light intensities. The deduced results demonstrate that ZnO nanowires and their Schottky contacts with Au electrodes both contribute to photosensitivity and the MSM structures with ZnO nanowires are potentially applicable for photonic devices.

Electron-transporting boron-doped polycyclic aromatic hydrocarbons:Facile synthesis and heteroatom doping positions-modulated optoelectronic properties

While heteroatom doping serves as a powerful strategy for devising novel polycyclic aromatic hydrocarbons(PAHs), the further fine-tuning of optoelectronic properties via the precisely altering of doping patterns remains a challenge. Herein, by changing the doping positions of heteroatoms in a diindenopyrene skeleton, we report two isomeric boron, sulfur-embedded PAHs, named Anti-B_(2)S_(2) and Syn-B_(2)S_(2), as electron transporting semiconductors. Detailed structure-property relationship studies revealed that the varied heteroatom positions not only change their physicochemical properties, but also largely affect their solid-state packing modes and Lewis base-triggered photophysical responses. With their low-lying frontier molecular orbital levels, n-type characteristics with electron mobilities up to 1.5 × 10^(-3)cm^(2)V^(-1)s^(-1)were achieved in solution-processed organic field-effect transistors. Our work revealed the critical role of controlling heteroatom doping patterns for designing advanced PAHs.

Structural and optoelectronic properties of sprayed Sb:SnO_2 thin films:Effects of substrate temperature and nozzle-to-substrate distance

The influence of substrate temperature and nozzle-to-substrate distance（NSD） on the structural,morphological, optical and electrical properties of Sb：SnO_2 thin films prepared by chemical spray pyrolysis has been analyzed.The structural,morphological,optical and electrical properties were characterized by using XRD,SEM, UV-visible spectrophotometry and Hall effect measurement techniques.It was seen that the films are polycrystalline, having a tetragonal crystal structure with strong orientation along the（200） reflection.The pyramidal crystallites formed due to coalescence were observed from SEM images.The values of highest conductivity,optical transmittance and figure of merit of about 1449（Ω·cm）^（-1）,70%and 5.2×10^（-3）□/Ω,respectively,were observed for a typical film deposited using optimal conditions（substrate temperature = 500℃and NSD = 30 cm）.

Optoelectronic properties and Seebeck coefficient in SnSe thin films

SnSe thin films of thickness 180 nm have been deposited on glass substrates by reactive evaporation at an optimized substrate temperature of 523 ± 5 K and pressure of 10^（-5） mbar.The as-prepared SnSe thin films are characterized for their structural,optical and electrical properties by various experimental techniques.The p-type conductivity,near-optimum direct band gap,high absorption coefficient and good photosensitivity of the SnSe thin film indicate its suitability for photovoltaic applications.The optical constants,loss factor,quality factor and optical conductivity of the films are evaluated.The results of Hall and thermoelectric power measurements are correlated to determine the density of states,Fermi energy and effective mass of carriers and are obtained as 2.8×10^（17）cm^（-3）,0.03 eV and 0.05m_0 respectively.The high Seebeck coefficient ≈ 7863 μV/K,reasonably good power factor ≈7.2×10^（-4） W/（m·K^2） and thermoelectric figure of merit ≈1.2 observed at 42 K suggests that,on further work,the prepared SnSe thin films can also be considered as a possible candidate for cryogenic thermoelectric applications.

Organic semiconductor nanostructures:optoelectronic properties,modification strategies,and photocatalytic applications

Organic semiconductors(OSCs)possess diverse chemical structures and tailored optoelectronic properties via simple chemical modifications,so increasing use of them are found in efficient visible-light photo-catalysis.However,the weak chemical bonds and the poor charge behavior(e.g.,low concentration of free charge carriers,low carrier mobility)intrinsic in them,always incur quite limited stability and efficiency.Therefore,the assembly of them into refined nanostructures or nanocomposites is usually proposed to enhance their optoelectronic properties,as well as the photocatalytic efficiency and reliability.Zero-dimensional(0D)nanoparticles are low in size and hence high specific surface area(SSA);One-dimensional(1D)nanostructures are usually arranged in an orderly long range thus leading to low surface defect density and increased carrier mobility;Two-dimensional(2D)nanostructures are particularly capa-ble of enhancing the photogenerated charge utilization because of their large reaction sites and shortened charge transport length.Furthermore,the building of heterogeneous interfaces in the nanocomposites can effectively facilitate the special charge separation.All these highlight the importance of organic nanos-tructures in improving the photocatalytic activity and stability.Therefore,organic semiconductor nanostructures(OSNs)have been increasingly used in the photocatalytic water splitting into H_(2) and O_(2),CO_(2) reduction,pollutant decomposition,disinfection,etc.In this review,we first examine the important optoelectronic properties of OSNs that govern the photocatalytic processes;we then analyze different classes of OSNs and their mechanistic pathways,with an emphasis on the structure-property relationships;we also introduced various photocatalytic applications of OSNs;we lastly propose the challenges and future outlook in real use.

Modulated optical and ferroelectric properties in a lateral structured ferroelectric/semiconductor van der Waals heterojunction

Modulation between optical and ferroelectric properties was realized in a lateral structured ferroelectric CuInP_(2)S_(6)(CIPS)/semiconductor MoS_(2) van der Waals heterojunction.The ferroelectric hysteresis loop area was modulated by the optical field.Two types of photodetection properties can be realized in a device by changing the ON and OFF states of the ferroelectric layer.The device was used as a photodetector in the OFF state but not in the ON state.The higher tunnelling electroresistance(~1.4×10^(4))in a lateral structured ferroelectric tunnelling junction was crucial,and it was analyzed and modulated by the barrier height and width of the ferroelectric CIPS/semiconductor MoS_(2) Schottky junction.The new parameter of the ferroelectric hysteresis loop area as a function of light intensity was introduced to analyze the relationship between the ferroelectric and photodetection properties.The proposed device has potential application as an optoelectronic sensory cell in the biological nervous system or as a new type of photodetector.

Synthesis and optoelectronic properties of a novel molecular semiconductor of dithieno[5,6-b:11,12-b']coronene-2,3,8,9-tetracarboxylic tetraester

A facile procedure for the synthesis ofdithieno[5,6-b：11,12-b＇]coronene-2,3,8,9-tetracarboxylic tetra（2- ethylhexyl）ester （DTCTI＇E-EH） from readily available perylene-3,4,9,10-tetracaroboxylic dianhydride is described. The electronic properties of DTCTTE-EH were elucidated on the basis of UV-vis spectra, emission spectrum and electrochemical measurement, which demonstrate that DTCTTE is a new class of components for promising semiconducting materials.

Syntheses,Crystal Structures and Optoelectronic Properties of Two New Inorganic Thioantimonates

Two new thioantimonates,(NH4)2Sb10S16(1)and K1.4(NH4)0.6Sb10S16(2),have been synthesized by solvothermal method with the yields of 80%and 85%,respectively.Single-crystal X-ray diffraction(SCXRD)study reveals that 1 crystallizes in the monoclinic space group of Pn with a=8.1284(4),b=19.4587(9),c=9.1030(4)A,β=91.736(5)°,V=1439.14(12)A^(3),Z=2,Dc=4.077 g·cm^(-3),F(000)=1576,μ=10.389 mm^(-1),R=0.0343 and w R=0.0624(I>2σ(I));2 also crystallizes in the monoclinic space group of Pn with a=8.0989(6),b=19.3730(17),c=9.0411(6)A,β=91.879(6)°,V=1417.79(19)A^(3),Z=2,Dc=4.207 g·cm^(-3),F(000)=1598,μ=10.748 mm-1,R=0.0323 and w R=0.0664(I>2σ(I)).The anionic frameworks of two compounds both feature two-dimensional(2D)[Sb10S16]n2n-layers.The stabilities and optoelectronic properties of 1 and 2 have been characterized.In particular,they are stable under acidic or alkaline conditions(pH=0 or 12.5),showing excellent acid-based resistance.

Effects of ⅢB transition metals on optoelectronic and magnetic properties of HoMnO_3: A first principles study

The optoelectronic and magnetic properties of pure HoMnO3 and Ho0.67T0.33MnO3 （T = La, Y） alloys in hexagonal phase are theoretically investigated by using the first-principles calculations. The investigations are performed by means of the density functional theory through using the spin polarized generalized gradient approximation plus the Hubbard potential （SPGGA ＋ U, Ueff =3 eV）. The studied material HoMnO3 exhibits two indirect band gaps： 1.58 eV for the spin- up state and 0.72 eV for the spin-down state along the S-G direction within the SPGGA ＋ U approximation. It is found that the band gap of pure HoMnO3 for the spin-up state increases with increasing La and Y dopants. The results show that all of the studied materials have semi-metallic behaviors for the spin-up state and semiconducting character for the spin-down state. The substitutions of La and Y for Ho in HoMnO3 cause the static dielectric constant （ε0） to increase in the x direction but to decrease in the z direction. The calculated optical conductivity spectrum of HoMnO3 in a low energy range is in good agreement with the recent experimental data.

Theoretical investigation of halide perovskites for solar cell and optoelectronic applications

The solar cell based on organic-inorganic hybrid halide perovskite is progressing amazingly fast in last decade owing to the robust experimental and theoretical investigations. First-principles calculation is one of the crucial ways to understand the nature of the materials and is practically helpful to the development and application of perovskite solar cells. Here, we briefly review the progress of theoretical studies we made in the last few years on the modification of electronic structures of perovskites by varying the composition, configuration, and structure, and the new understandings into the defect properties of halide perovskites for solar cell and optoelectronic applications. These understandings are foundations and new starting points for future investigations. We hope the experience and inspiration gained from these studies encourage more theoretical explorations for new functional perovskite-based materials.

Preparation,Properties,and Applications of Low-Dimensional Molecular Organic Nanomaterials

In recent years, great progress has been made in research and development of small-molecule organic materials with various low-dimensional nanostructures. This paper presents a comprehensive review of recent research progress in this field, including preparation, electronic and optoelectronic properties and applications. First, an introduction gives to the reprecipitation, soft templates methods, and progress in synthesis and morphological control of low-dimensional small-molecule organic nanomaterials. Their unique optical and electronic properties and research progress in these aspects are reviewed and discussed in detail. Applications based on low-dimensional small-molecule organic nanomaterials are briefly described. Finally, some perspectives to the future development of this field are addressed.

Influence of reaction gas flows on the properties of SiGe:H thin film prepared by plasma assisted reactive thermal chemical vapour deposition

A new preparing technology, very high frequency plasma assisted reactive thermal chemical vapour deposition （VHFPA-RTCVD）, is introduced to prepare SiGe：H thin films on substrate kept at a lower temperature. In the previous work, reactive thermal chemical vapour deposition （I^TCVD） technology was successfully used to prepare SiGe：H thin films, but the temperature of the substrate needed to exceed 400℃. In this work, very high frequency plasma method is used to assist RTCVD technology in reducing the temperature of substrate by largely enhancing the temperature of reacting gases on the surface of the substrate. The growth rate, structural properties, surface morphology, photo- conductivity and dark-conductivity of SiGe：H thin films prepared by this new technology are investigated for films with different germanium concentrations, and the experimental results are discussed.

Stability and optoelectronic property of lead-free halide double perovskite Cs_(2)B′BiI_(6)(B′=Li,Na and K)

Although lead-based perovskite solar cells have achieved more than 25%power conversion efficiency,the toxicity of lead and instability are still urgent problems faced in industrial application.Lead-free halide double perovskite(DP)materials are promising candidates to resolve these issues.Based on the density functional theory,we explore the geometric stability,thermodynamic stability,mechanical stability,electronic structures,and optical properties of theCs_(2)B 0BiI_(6)(B 0=Li,Na and K)DP materials.By analyzing the tolerance factor and octahedral factor,we find the geometric stabilities ofCs_(2)NaBiI_(6) andCs_(2)KBiI_(6) DPs are better thanCs_(2)LiBiI_(6).By calculating the total energy,formation energy and decomposition energy,we propose that the most favorable structure ofCs_(2)B 0BiI_(6) is the orthorhombic phase,andCs_(2)LiBiI_(6) is less stable relative to the other two counterparts from an energetic viewpoint.Mechanical stability evaluations reveal that the orthorhombicCs_(2)LiBiI_(6) material is less stable relative to the isostructuralCs_(2)NaBiI_(6) andCs_(2)KBiI_(6) DPs.The mechanical property calculations indicate that theCs_(2)B 0BiI_(6) DPs possess good ductility,which can be used as flexible materials.Electronic structures and optical property calculations show that the orthorhombicCs_(2)B 0BiI_(6) DPs have suitable band gap values,weaker exciton binding energies,and excellent optical absorption performance in the visible-light range.Based on the above comprehensive assessments,we can conclude that the orthorhombic Cs_(2)NaBiI_(6) and Cs_(2)KBiI_(6) DPs with good stability are promising candidates for solar cell applications.

Stability and optoelectronic property of low-dimensional organic tin bromide perovskites

The toxicity and degradation of hybrid lead-halide perovskites hinder their extensive applications.It is thus of great importance to explore non-toxic alternative materials with excellent stability and optoelectronic property.We investigate the atomic structures and optoelectronic properties of non-toxic organic tin bromide perovskites(OTBP)with one/zerodimensional(1D/0D)structures by first-principles calculations.The calculated atomic structures show that the 1D/0D OTBPs are stable and the structure of inorganic octahedra in 0D is higher order than that in 1D.Moreover,the origination of exceptional purity emitting light in experiments is explained based on the calculated electronic structure.