Promising Candidate For Photovoltaic Applications Research Articles

DFT+U investigation of electronic, optical, and thermoelectric properties of YAuX (X=Si or Ge or Sn) half-Heusler alloys

Half-heusler alloys are fascinating thermoelectric materials because they have superior mechanical and transport properties. In this study, we used dft+u calculations and the Boltztrap equation to examine the electronic, optical, and thermoelectric properties of YAuSi, YAuGe, and YAuSn half-heusler alloys. The DFT+U approach predicted band gaps of 1.2767 eV, 0.611 eV, and 1.5741 eV for YAuGe, YAUSn, and YAuSi, respectively. We also observed that all materials under consideration have a broad absorption spectrum ranging from 1 eV to 12 eV, with notable peaks in the visible and UV ranges. The obtained opto-electronic properties position the three alloys as promising candidates for photovoltaic applications. Finally, thermoelectric property calculations revealed that the figure of merit values for YAuSi, YAuGe, and YAuSn HH alloys were 0.730, 0.726, and 0.736 at 800 K, respectively suggesting the materials are also suitable candidates for application in the field of thermoelectricity

Realizing Stable Perovskite Solar Cells with Efficiency Exceeding 25.6% Through Crystallization Kinetics and Spatial Orientation Regulation.

Organic-inorganic hybrid perovskites have emerged as highly promising candidates for photovoltaic applications, owing to the exceptional optoelectronic properties and low cost. Nonetheless, the performance and stability of solar cells suffer from the defect states of perovskite films aroused by non-optically active phases and non-centralized crystal orientation. Herein, a versatile organic molecule, Hydantoin, to modulate the crystallization of perovskite, is developed. Benefiting from the diverse functional groups, more spatially oriented perovskite films with high crystallinity are formed. This enhancement is accompanied by a conspicuous reduction in defect density, yielding efficiency of 25.66% (certified 25.15%), with superb environmental stability. Notably, under the standard measurement conditions (ISOS-L-1I), the maximum power point (MPP) output maintains 96.8% of the initial efficiency for 1600 h and exhibits excellent ion migration suppression. The synergistic regulation of crystallization and spatial orientation offers novel avenues for propelling perovskite solar cell (PSC) development.

A DFT study of structural, electronic, optical, thermal and mechanical properties of cubic perovskite KGeX3 (X = Cl, Br) compound for solar cell applications

This study examined the structural, electronic, optical, mechanical, and thermal properties of K-based halide perovskites KGeX3 (X = Cl, Br). All the calculations have been carried out using the DFT-based CASTEP simulation package with an ultra-soft pseudo-potential plane wave and PBE-GGA technique. Both the studied perovskite compounds are stable in terms of mechanical and thermal stability. The calculated electronic properties indicate that both materials have a semiconducting behavior with a direct band gap. The band gap value is 0.92 and 0.62 eV for KGeCl3 and KGeBr3, respectively. The analysis of the electronic properties reveals a notable reduction in the bandgap as chlorine (Cl) is substituted with bromine (Br), decreasing from 0.92 to 0.52 eV. The results of our calculations are in good agreement with the previously reported research. The optical properties analysis reveals that both materials demonstrate high absorption and minimal reflection within the visible spectrum. The determined values for Poisson’s and Pugh’s ratios suggest that studied materials demonstrate a ductile behavior. The obtained values of Debye temperature are 265.25 and 191.62 K for KGeCl3 and KGeBr3, respectively. Based on their appropriate direct band gap and high absorption coefficient, these materials are considered promising candidates for photovoltaic applications, and are proposed as ideal potential materials for solar cells applications.

Optimization of a GaAs/AlGaAs p-i-n heterojunction nanowire solar cell for improved optical and electrical properties

GaAs/AlGaAs based nanowires are promising candidates for photovoltaic applications due to their high absorption coefficient, low surface reflection, and efficient collection of photogenerated carriers. This study focuses on optimizing the performance of p-i-n GaAs/AlGaAs nanowire solar cell arrays having a radial junction using optoelectronic simulations. The research investigates the optimal doping for the GaAs core and AlGaAs shell, as well as the impact of shell thickness and junction positions on solar cell performance. Additionally, the study examines the effect of various surface effects, including the presence of surface traps, surface recombination velocities, and associated lifetime degradation. Our studies find that a high doping density for the shell and core region is crucial for achieving an appropriate band configuration and carrier extraction. It also highlights that having a larger doping density is more important than having a larger lifetime. Finally, the research examines the effect of different aluminum compositions on photogeneration inside the nanowire and shows that having a high aluminum composition can confine most photogeneration to inner GaAs regions, potentially allowing for thicker AlGaAs shells, which can efficiently prevent surface recombination.

Disorder on Mixed Cation Halide Perovskite for Photovoltaic Applications.

With reduced toxicity and tunable optoelectronic properties, mixed cation halide perovskites (MCHPs) featuring partially substituted Pb with Sn and Ge have emerged as promising candidates for photovoltaic applications. However, the introduction of the disorder through large-scale preparation and alloying strategies leads to a significant challenge in comprehending the disorder's microscopic-level impact. Here, we found that, in addition to compositional variation, a synergy of disorder and cation radii ratio significantly affects optoelectronic properties. For Pb-Ge/Ge-Sn MCHPs, severe octahedral distortion with increasing degree of disorder adjusted their bandgaps in a wide range, giving rise to large effective masses, exciton binding energies, and weak visible absorption coefficients. The synergy of disorder and distortion transforms the Wannier excitons into localized characteristics, whereas the optoelectronic properties of Pb-Sn MCHPs are modulated by the disorder. Our work highlights the role of disorder in the tunability of optoelectronic properties, providing a novel strategy for designing photovoltaic materials.

Modeling of highly efficient CNGS based kesterite solar cell: A DFT study along with SCAPS-1D analysis

The electronic and optical properties of Cu2NiGeS4 (CNGS) are examined using the first-principle DFT calculations. A unique mBJ + U potential method is used for the band gap energy calculation of CNGS. With a remarkably high absorption coefficient (104 cm−1), CNGS has become a promising candidate for photovoltaic applications. SCAPS-1D tool is used to simulate a thin-film solar cell with a Mo/MoS2/Cu2NiGeS4 (CNGS)/CdS/ZnO/ZnO:Al structure. The impact of various factors, such as layer thickness, donor and acceptor concentrations, and defect density on the CNGS layer was explored. This study also explores the combination of suitable buffer layers (such as CdS, ZnS, and their alloy Cd1−xZnxS), along with different doping concentrations and thicknesses, to be used as suitable buffer layers in the CNGS solar cell. The simulation outcomes suggest that the optimal thickness for the absorption layer in CNGS solar cells is between 2000 and 2400 nm, while the ideal thickness for MoS2 is 100 nm. The buffer layer should be between 20 and 50 nm. Keeping the defect density of CNGS below 1014 cm−3 is crucial for high efficiency. The optimized results yield an efficiency conversion rate of 20.05%, a 66.77% fill factor, a short-circuit current of 29.67 mA/cm2 and an open-circuit voltage of 0.983 V.

Electronic, optical, and thermoelectric properties of multifunctional zintl compound BaAg2Te2 for energy conversion

Using the FP-APW + lo method, the structural, electronic, and optical properties of the Zintl BaAg2Te2 compound were investigated. The calculated unit cell parameters are well matching with the experimental results. In addition, the study of electronic properties reveals that BaAg2Te2 is a semiconductor with a direct bandgap of about 1.445 eV. The optical constants such as loss energy, refractive index, reflectivity, and absorption coefficient have been calculated and analyzed. These constants show a clear anisotropy caused by the different electron polarizability in the x-, y-, and z-directions. Moreover, the direct bandgap and good optical absorption make BaAg2Te2 promising candidates for photovoltaic applications. The thermoelectric properties of the BaAg2Te2 compound in the x, y, and z directions have been studied to obtain the Seebeck coefficient, electrical conductivity, electronic thermal conductivity, power factor, and figure of merit (ZT) against temperature and carrier concentrations. Our investigations showed an improvement in the ZT values of BaAg2Te2 with increase in temperature. Moreover, the BaAg2Te2 demonstrated optimal ZT values along the y-axis.

Investigating the effect of halogens on the electronic and optical properties of lead‐free double halide perovskites based on CuBi

AbstractIn recent years, three‐dimensional (3D) lead‐free double halide perovskites have been considered promising candidates for photovoltaic applications due to their high stability and the use of non‐toxic materials, and the absence of organic materials in their structure. The structural, electronic, and optical properties of 3D double Halide perovskites and were investigated in this paper using first‐principles density functional theory (DFT) simulation with BLYP approximation. The results showed that structures and have an indirect band gap, high absorption coefficient, low reflection, and high conductivity. A redshift of absorption edge and band gap shrinkage has been observed in the structure with an increase in the ionic radius of the halogen, which indicates the unique features of structure for photovoltaic applications, LED, laser, and other optoelectronic devices.

Various dopant elements impact on the density of state of ternary CuSbSe2 chalcostibite: A theoretical study

This work aims to study the doping effect of B, Al, and Bi elements on the electronic distribution of CuSbSe2 compounds. The structural and electronic properties of Cu(1-x)AxSbSe2 and CuSb(1-y)XySe2 (A = B and Al, X = Al and Bi) were investigated by GGA-PBE and GGA-PBE + SIC approximations. Where x and y take values of 0%, 3%, 5%, 7%, and 10%. The optical properties of the pristine CuSbSe2 were calculated using the WIEN2K package based on the GGA-PBE and GGA-PBE + mBJ. The transport properties of CuSbSe2 were realised through the BoltzTraP package combined with the WIEN2K code using the GGA-PBE approximation. The electronic properties prove the n-type semiconductor with a direct bandgap of 0.68 eV. The optical properties of the pristine semiconductor make it a promising candidate for photovoltaic applications. Furthermore, a transition from semiconductor to metallic behavior is observed after doping with B and Bi elements.

High-Efficiency CsPbI2Br Perovskite Solar Cells with over 83% Fill Factor by Synergistic Effects of a Multifunctional Additive.

All-inorganic CsPbI2Br with outstanding thermal stability and excellent photoelectric properties is considered as a promising candidate for photovoltaic applications. However, the efficiency of CsPbI2Br perovskite solar cells (PSCs) is still much lower than that of their organic-inorganic hybrid counterparts or CsPbI3-based devices. Herein, we obtained an optimized CsPbI2Br PSC (0.09 cm2) with a champion efficiency of 17.38% and a record fill factor of 83.6% by introducing potassium anthraquinone-1,8-disulfonate (DAD) in the precursor solution. The synergistic effect between the electronegative functional groups and K+ ions in the DAD structure can not only effectively regulate the crystallization growth process to improve the crystalline quality and stability of photo-active CsPbI2Br but also optimize the energy level alignment and passivate the defects to improve the carrier transport properties. The efficiency of the corresponding large-area device (5 cm × 5 cm with an active area of 19.25 cm2) reached 13.20%. Moreover, the optimized CsPbI2Br PSC exhibited negligible hysteresis and enhanced long-term storage stability as well as thermal stability. Our method produces more stable photo-active CsPbI2Br with excellent photoelectric properties for industrial applications or perovskite/silicon tandem cells.

Electronic and Optical Properties of CH3NH3SnI3 and CH(NH2)2SnI3 Perovskite Solar Cell

Using first‐principles calculations, a study on the electronic and optical characteristics of perovskite solar cells containing the orthorhombic phases CH3NH3SnI3 and CH(NH2)2SnI3 is conducted. The analysis includes the examination of relaxed geometry structures, electronic band structures, charge density distributions, and van Hove singularities in the density of states to thoroughly examine the orbital hybridizations in chemical bonds. The optical properties of the materials with and without excitonic effects by analyzing dielectric functions, energy loss functions, absorption coefficients, and reflectance spectra are also studied. The findings identify the close connections between the initial and final orbital hybridizations, as well as prominent optical excitations. Based on the computational predictions, It is believed that lead‐free materials such as CH3NH3SnI3 and CH(NH2)2SnI3 are promising candidates for photovoltaic applications and are worth experimental testing.

Prediction of new 2D Hf2Br2N2 monolayer as a promising candidate for photovoltaic applications

In the present work, the structural and optoelectronic properties of pristine and strained hexagonal Hf2Br2N2 monolayer have been investigated using the first-principles calculations. The binding energy, phonon dispersion calculations, and molecular dynamics simulations demonstrated that this monolayer has dynamic and thermal stabilities depending. It was revealed that the unstrained Hf2Br2N2 monolayer is semiconducting with an indirect bandgap of 1.809 eV/2.853 eV using PBE/HSE06 methods, which is perfect for powerful light absorption. Besides, the results show that the biaxial strain is an effective tool for adjusting the energy gap where the indirect energy gap under the strain effects ranged within a range of 2.791 eV at −6% to 2.968 eV at 6%. Our results show that the Hf2Br2N2 monolayer has a high electron carrier mobility of 7780.2 cm2/V.s. Furthermore, it was found that the Hf2Br2N2 monolayer has the strongest absorption ranging from IR to UV region of the light spectrum. The outcomes of this work revealed that biaxial strain can be an effective technique for tuning the optoelectronic properties of the Hf2Br2N2 monolayer. Moreover, these results confirm that this monolayer can be suitable for photodetectors and photovoltaics applications.

Reversible degradation-assisted interface engineering via Cs4PbBr6 nanocrystals to boost the performance of CsPbI2Br perovskite solar cells

CsPbI2Br perovskites are promising candidates for photovoltaic applications owing to the trade-off between the optoelectronic properties and phase stability of cesium-based inorganic perovskites. However, the major shortcomings of CsPbI2Br perovskite solar cells (PSCs), namely energy loss and poor moisture resistance, still need to be addressed. In this work, reversible degradation-assisted decoration with Cs4PbBr6 nanocrystals (NCs) is used to passivate the perovskite/hole transporting material (HTM) interface. Moisture-induced Cs4PbBr6 decomposition products (CsPbBr3 and CsBr) and CsPbI2−xBr1+x (x > 0), generated as a result of halide anion exchange between CsPbI2Br and Cs4PbBr6 or its decomposition products, are found to improve the quality of the CsPbI2Br film and suppress the trap state density. In addition, the decoration achieves desirable energy-level alignments at the CsPbI2Br/HTM interface and raises the Fermi level of the CsPbI2Br film, thereby strengthening the built-in electric field between the perovskite and HTM. As a result, the optimized CsPbI2Br PSC has a champion efficiency of 15.52% with an open-circuit voltage of 1.30 V (mean value: 1.29 V). The unencapsulated CsPbI2Br film and device both exhibit high air stability (∼40% humidity), and the latter retains 90% of its initial efficiency after a 500 h aging test.

Influence of film thickness on microstructure and optical properties of Bismuth Ferrite (BFO) for photovoltaic application

Bismuth Ferrite (BFO) film with a low bandgap value is a promising candidate for photovoltaic applications. This study discussed the effects of film thickness on the microstructure and optical properties of BFO films. BFO films were deposited on the Quartz-Silicon substrates using the chemical solution deposition (CSD) method. The thickness variation was conducted by varying the deposited layer number which correspond to the thickness values of 252 and 405 nm, respectively. The XRD analysis showed that increasing of films thickness had no significant effect on the crystal structure. It revealed that the XRD peak intensities increase, however, the lattice parameters, crystallite size, and crystallinity are relatively in the close values as the increasing films thickness. The Scanning Electron Microscopy (SEM) analysis exhibited the larger grain size of the BFO films with the increasing films thickness. According to the UV-Vis spectrophotometer results, the bandgap values reduced from 2.48 eV to 2.5 eV as the thicker film. Finally, The I-V curve presented that the higher films thickness induced the higher efficiency of the BFO film from 0.97 % to 2.1%. The BFO film with higher thickness could exhibit the better performance for photovoltaic application.

Polaronic Signatures in Doped and Undoped Cesium Lead Halide Perovskite Nanocrystals through a Photoinduced Raman Mode.

Lead halide perovskites (LHPs) are promising candidates for photovoltaic applications as they exhibit large carrier diffusion lengths and long carrier lifetimes among many other interesting properties. One of the widely accepted mechanisms for these properties is polaron formation, which is mainly driven by octahedral distortions of the inorganic framework. Since structure modifications of the framework largely affect associated distortions, we investigated Mn-doped and undoped CsPbX3 (where X = Cl, Br, Cl/Br) using a local probe via micro-Raman spectroscopy and density functional theory (DFT) calculations for polaron formation. Our results highlight a new vibrational lattice mode at 132 cm-1 due to polaronic distortion upon photoinduction. From the DFT studies, we have shown that the polaronic states are dominated by the B-site cation in the perovskite structure, but it is the strong covalent overlap of the halide which determines its stability. This elucidation to map polaronic signatures with excellent spatial resolution using traditional Raman spectroscopy can be used as a simple tool to understand the structural changes and their impacted electronic properties and thus design superior devices using its in situ applications.

Orientation dependence of polarization-modulated photovoltaic effect of relaxor-based Pb(In1/2Nb1/2)O3–Pb(Mg1/3Nb2/3)O3–PbTiO3 single crystals

Noncentrosymmetry ferroelectric materials coupled with switchable polarization are promising candidates for photovoltaic applications because of their unique dissociation mechanism of photogenerated excitons associated with bulk polarization. Here, we study the photovoltaic properties of relaxor-based 24Pb(In1/2Nb1/2)O3–47Pb(Mg1/3Nb2/3)O3–29PbTiO3 (24PIN–47PMN–29PT) single crystals with a large remnant polarization and a proper optical bandgap along various crystallographic orientations. The 24PIN–47PMN–29PT single crystals are found to exhibit a modulated photovoltaic response by switching the poling direction, while their current–voltage curves present a linear relation. The superior photovoltaic response in the [111]C‐oriented crystal suggests that the photovoltage is strongly dependent on the crystallographic direction because of the polarization intensity difference. In addition, the domain configuration, phase structure, ferroelectric performance, and optical characteristics of 24PIN–47PMN–29PT single crystals are investigated, providing clues to the origin of the anomalous photovoltaic effect of these single crystals. Our results indicate that the photovoltaic performance of 24PIN–47PMN–29PT single crystals can expand their potential applications in photovoltaic devices, photorefraction, and photorefractive optical applications.

The structural, electronic and optical properties of all-inorganic CsPb1−xSnxBr3 perovskite: A theoretical study

All-inorganic halide perovskites have emerged as the promising candidates for optoelectronic device. First-principles calculations are conducted to explore the structural, electronic and optical properties of the CsPb1−xSnxBr3 compounds. The results indicate that these inorganic compounds show high stability and the trend of phase segregation is not found. The HSE06 functional can provide accurate band gap for CsPb1−xSnxBr3 (x < 1). The direct band gap of CsPb1−xSnxBr3 is reduced by increasing the concentration of Sn doping. In view of the toxic Pb element and the instability of Sn2+, CsPb0.50Sn0.50Br3 has a suitable band gap and shows strong optical absorption coefficient, which is proposed to be the most promising candidate for photovoltaic applications. Our work demonstrates a useful strategy for developing stable and suitable band gap of efficient inorganic lead-less perovskites.

Bulk Passivation and Interfacial Passivation for Perovskite Solar Cells: Which One is More Effective?

AbstractPerovskite solar cells (PSCs) have emerged as promising candidates for photovoltaic applications because of their superior optoelectronic properties. The power conversion efficiency of 25.5% has been achieved at an astonishing speed from the debut of 3.8%. However, the notoriously poor stability stemming from the solution fabrication process and uncontrollable rapid crystallization limits the commercialization of PSCs. Thus defects are inevitable among the bulk films and interfaces. Herein, recent progress about defects passivation by additive strategy among the bulk film, are discussed. More importantly, the defects passivation strategy for perovskite/electron transport layer and perovskite/hole transport layer interfaces are summarized. Furthermore, how defects passivation and ion migration would affect the stability performance of the perovskite devices are elaborated. Finally, the current challenges for commercialization prospects of perovskite photovoltaic applications are discussed.

BaZrS3 Chalcogenide Perovskite Thin Films by H2S Sulfurization of Oxide Precursors.

The earth-abundant ternary compound BaZrS3, which crystallizes in the perovskite-type structure, has come into view as a promising candidate for photovoltaic applications. We present the synthesis and characterization of polycrystalline perovskite-type BaZrS3 thin films. BaZrO3 precursor layers were deposited by pulsed laser deposition and sulfurized at various temperatures in an argon-diluted H2S atmosphere. We observe increasing incorporation of sulfur for higher annealing temperatures, accompanied by a red shift of the absorption edge, with a bandgap of Eg = 1.99 eV and a large absorption strength >105 cm-1 obtained for sulfurization temperatures of 1000 °C. X-ray diffraction analysis and SEM indicate enhanced crystallization at the higher annealing temperatures, but no evidence for a crystalline solid solution between the BaZrO3 and BaZrS3 phases is found. The charge carrier sum mobility estimated from optical-pump-terahertz-probe spectroscopy indicates increasing mobilities with increasing sulfurization temperature, reaching maximum values of up to ∼2 cm2 V-1 s-1.

Electrical impedance spectroscopy study of unsubstituted palladium (II) phthalocyanine

A pressed pellet of unsubstituted palladium (II) phthalocyanine (PdPc) was synthesized and characterized by UV-Vis transmittance and impedance spectroscopy. Optical absorbance analysis revealed that upon increasing the concentration, the absorption at 630 nm became more intense, demonstrating strong aggregation at high concentrations. For the synthesized PdPc pellet, the absorbance decreased beyond 800 nm, and the direct band gap energy was 1.95 eV. The electric properties of the sample were studied for a range of frequency (40–107 Hz) and temperature (300–660 K) using complex impedance analysis. The activation energy and the relaxation time values for both time and frequency ranges were close to each other, suggesting that the electrical conduction and relaxation phenomena were controlled by the same type of charge carrier in the sample. Notably, the sample exhibited a semiconductor–metal transition at temperature TSM = 560 K. The AC-conductance was satisfactorily explained using the Jonscher universal power law. The electrical transport mechanism was dominated by the overlapping large polaron tunneling (OLPT) model. Furthermore, impedance spectroscopy analysis revealed a non-Debye-type relaxation. The Nyquist plot indicates the presence of grains and grain boundary effects. The results demonstrate that this material may be a promising candidate for photovoltaic applications.