Materials For Solar Cell Applications Research Articles

The structural, mechanical, and optoelectronic properties of Cu2-II-Sn-VI4 (II = Mg, Zn, Cd; VI = S, Se): A DFT study

Quaternary compound Cu2ZnSnX4 (X = S, Se) is of great interest to many researchers for photovoltaic applications in recent years. In the present study, the first-principles calculations are performed to investigate the influence of cation substitution on the different physical properties of Cu2ZnSnS4 (CZTS) and Cu2ZnSnSe4 (CZTSe). The difference in stability between two Kesterite and Stannite structures is examined for each compound. The results show that the pristine Kesterite structure will be transformed into the Stannite structure when the Zn atoms are replaced by the Mg or Cd atoms. Our results are consistent well with the available literature. The mechanical stability of six compounds are proved and they are ductile materials. The allowed direct electronic transition is found for all compounds at the Γ point. The band gap variation is analyzed in detail. The band gaps calculated from hybrid functional PBE0 of the studied compounds can agree well with the experimental data. The suitable band gap values of 1.12 and 1.28 eV are obtained for Cu2MgSnSe4 (CMTSe) and Cu2CdSnS4 (CCTS) in single-junction solar cells, whereas the band gaps of Cu2MgSnS4 (CMTS, 1.70 eV) and Cu2CdSnSe4 (CCTSe, 0.77 eV) are too large or small. The band gap energy difference between two tetragonal structures is shown to be negligible for CMTS, CMTSe, CCTS, and CCTSe. Furthermore, the optical properties are compared, and CMTSe and CCTS show strong light absorption capacity from 300 to 800 nm. Our study indicates that both CMTSe and CCTS are the promising materials for solar cell applications.

Effect of indium vacancy point defect on the structural, electronic and optical properties of double perovskite halide Cs2InSbCl6

Efforts to replace the lead-based perovskite have gain significant improvements in the last decade. Lead free double halide perovskite are being considered to replace the toxic lead-based perovskite materials for solar cell applications. Density functional theory (DFT) and linear response time-dependent density functional theory (TDDFT) are used in this study to simulate and investigate the effect of vacancy in the Indium (In) site of leadfree double halide perovskite A2BB′X6 (A = Cs; B = In, B′ = Sb; X = Cl) on the structural, electronic, and optical properties for possible solar cell application. On the structural properties, the total bond length of the material Cs2InSbCl6 was found to be 30.3848 Å and the creation of the indium vacancy raises the value to 30.594 Å. The bulk modulus of Cs2InSbCl6 was calculated to be 28.44 Gpa and 26.22 Gpa for Cs2In-xSbCl6. The calculated band structure for Cs2InSbCl6 reveals semiconducting behavior with a direct energy band gap of 0.99 eV along 𝛤 point symmetry while the created indium vacancy band structure reveals metallic behavior with an overlap of electronic states along the Γ - W – Γ symmetry. The result of the optical properties calculations shows that the material Cs2InSbCl6 has higher absorption coefficient, low refractive index, low reflectivity and higher conductivity when compared to the created indium vacancy material.

Theoretical study of the structure and fundamental properties of AZn2N2 (A = Ca, Sr, Ba)

The structure, stability, elastic, electronic, and optical properties of trigonal AZn 2 N 2 (A = Ca, Sr, Ba) are simulated and compared in this work. The stability and physical properties of BaZn 2 N 2 are mainly highlighted. According to the calculated results, three compounds are thermodynamically and mechanically stable, and they are brittle materials. The stability of trigonal BaZn 2 N 2 is confirmed by using the different theoretical approaches. The direct band gap transition is allowed at the Γ point for each compound. The predicted direct band gaps are 1.733, 1.507, and 1.510 eV for CaZn 2 N 2 , SrZn 2 N 2 , and BaZn 2 N 2 , respectively. The valence band is mostly composed of the N-2p orbitals, while the conduction band is mainly contributed from the Ca-3d/Sr-4d/Ba-5d orbitals. The results show that the electron shows high mobility for carrier transport, and the value of exciton binding energy is less than 80 meV. Furthermore, compared to CaZn 2 N 2 and SrZn 2 N 2 , BaZn 2 N 2 shows excellent light absorption capacity in the visible region. This study indicates that BaZn 2 N 2 is a desirable material for solar cell applications.

Roles of TOPO Coordinating Solvent on Prepared Nano-Flower/Star and Nano-Rods Nickel Sulphides for Solar Cells Applications.

The present study describes a cheap, safe, and stable chemical process for the formation of nickel sulphide (NiS) with the use of mixed and single molecular precursors. The production pathway is uncomplicated, energy-efficient, quick, and toxic-free, with large-scale commercialization potential. The obtained results show the effect of tri-N-octylphosphine oxide (TOPO) as a coordinating solvent on the reaction chemistry, size distributions, morphology, and optical properties of both precursors. Ni[N,N-benz-N-p-anisldtc] as NiSa, Ni[N,N-benzldtc] as NiSb, and Ni[N-p-anisldtc] as NiSc thermally decompose in a single step at 333–334 °C. The X-ray diffraction peaks for NiSa, NiSb, and NiSc matched well with the cubic NiS nanoparticles and corresponded to planes of (111), (220), and (311). The extrapolated linear part from the Tauc plots reveals band gap values of 3.12 eV, 2.95 eV, and 2.5 eV, which confirms the three samples as potential materials for solar cell applications. The transmission electron microscopy (TEM) technique affirmed the quantum dot size distribution at 19.69–28.19 nm for NISa, 9.08–16.63 nm for NISb, and 9.37–10.49 nm for NISc, respectively. NiSa and NiSc show a clearly distinguishable flower/star like morphology, while NiSb displays a compact nano-rod shape. To the best of the authors’ knowledge, very few studies have been reported on the flower/star like and nano-rod shapes, but none with the dithiocarbamate molecular precursor for NiS nanoparticles.

ZnO Multilayer Thin Films as The Seed Layer for ZnO Nanorods: Morphology, Structural and Optical properties

The effect of zinc oxide (ZnO) multilayer thin film thicknesses, deposited via the sol-gel spin coating technique, on the morphology, structural and optical properties of ZnO nanorods (ZNR) grown on the ZnO thin films were explored in this investigation. The ZNR was grown using the chemical bath deposition method on the ZnO thin film seed layer (SL). We found that ZnO thin film SL morphology changes according to the number of layers based on the results. Eventually, these changes also influence the structures of ZNR. ZNR structures improved when the thickness of the seed layer increased. Besides the surface roughness, better crystalline quality films were obtained when more layers were deposited. This crystalline quality then influenced the optical characteristics of both ZnO and ZNR thin films. The optical properties from UV-Vis showed transmittance in the visible region, showing that the ZnO films produced were suitable to be applied to solar cells. ZNR-based solar cells have become one of the promising materials to be studied further due to the environment-friendly, low-cost, and well-abundant material for solar cell applications.

Effects of tensile strain on the electronic, optical and ferroelectric properties of a multifunctional R3c InFeO3 compound

The search for materials with appropriate ferroelectric and photovoltaic properties is an intense field of research. The main objective of these studies is to obtain efficient materials for solar cell applications. In this work, non-collinear spin density functional theory calculations are performed to describe the electronic, optical, and ferroelectric properties of a multiferroic R3c InFeO3 compound under tensile strain. Our studies reveal that under conditions of tensile strain, this material had ideal fundamental properties for photovoltaic applications. Under 9% tensile strain of the R3c InFeO3 unit cell volume (a = 5.536 Å and c = 13.808 Å), a direct energy band gap of 1.74 eV was found. With this energy band gap, the material absorbs the entire range of visible light, and for a film thickness of up to 100 nm it reaches a maximum photoconversion efficiency of 20%, a higher value than observed in some semiconductors that are used in practice. Furthermore, the effective mass of charge carriers (m*), and the exciton binding energy (Eb) are significantly decreased (m* < 0.4 m0 and Eb < 1.0 meV), which likely to lead to better charge mobility and easier separation of the electron-hole pair in the process of photoabsorption. Under this level of strain, the spontaneous electric polarization was reduced to 77.6 µC/cm2, a value that is still higher than other ferroelectric-photovoltaic materials.

Electronic and optical properties of Mg3XN (X = P, As, Sb, Bi) antiperovskites: The GW/BSE approach

Antiperovskites (APs) have several potential applications. Methods based on Density Functional Theory (DFT) have been applied to study the properties of APs. In this work, electronic and optical properties of Mg3XN (X = P, As, Sb, Bi) APs were investigated using the GW approximations and solution to the Bethe Salpeter Equation (BSE). The Mg3XN (X = P, As) were found to have direct band gaps while, Mg3XN (X = Sb, Bi) have indirect band gaps. The estimated G0W0/eVGW band gaps for Mg3PN, Mg3AsN, Mg3SbN, and Mg3BiN are 2.3328/2.6051, 2.1032/2.3620, 1.4156/1.6204 and 1.2917 eV/1.4760 eV, respectively. The inclusion of the spin–orbit coupling (soc) leads to a decrease in the G0W0/eVGW band gaps by about 15%/13% and 40%/33% for Mg3SbN and Mg3BiN, respectively. Optical properties obtained from the solution to BSE reveal that the APs could be promising materials for solar cell applications and optoelectronic devices.

Unveiling the fundamental physical properties of Cu2-xNaxZnSnX4 (X = S, Se) alloys for solar cell applications: a theoretical investigation

Quaternary chalcogenide compounds Cu2ZnSnS4 (CZTS) and Cu2ZnSnSe4 (CZTSe) are the promising absorber materials for solar cell applications. The impact of Na as an isovalent dopant for Cu on the structure, thermodynamic stability, mechanical, electronic, and optical properties of CZTS and CZTSe is examined for the first time. The computed lattice constants of Cu2-xNaxZnSnS4 (CNZTS) and Cu2-xNaxZnSnSe4 (CNZTSe) (x = 0, 0.5, 1, 1.5, and 2) are increased and decreased as a function of x for a and c, respectively. The stability of CNZTS and CNZTSe is ensured by their negative formation energies. The results show that all alloys are mechanically stable and ductile materials. The band gaps of CZTS and CZTSe are greatly broadened when Cu is replaced by Na. The tunable band gaps of CNZTS and CNZTSe are in the range of 1.19–3.08 eV and 0.65–2.30 eV, respectively. It is found that two novel compounds have suitable band gap values for solar cell applications, such as Cu1.5Na0.5ZnSnS4 (1.47 eV) and CuNaZnSnSe4 (1.43 eV). In addition, Cu1.5Na0.5ZnSnS4 and CuNaZnSnSe4 show good carrier mobility. The analysis of optical properties displays that CuNaZnSnSe4 exhibits a stronger absorption coefficient than those of CZTS and Cu1.5Na0.5ZnSnS4 at 300–500 nm. Combined with the band gap and light absorption, CuNaZnSnSe4 is the most promising material for solar cell applications.

First-Principles Study of Cu-Based Inorganic Hole Transport Materials for Solar Cell Applications.

Perovskite solar cells (PSCs) and dye-sensitized solar cells (DSCs) both represent promising strategies for the sustainable conversion of sunlight into electricity and fuels. However, a few flaws of current devices hinder the large-scale establishment of such technologies. On one hand, PSCs suffer from instabilities and undesired phenomena mostly linked to the perovskite/hole transport layer (HTL) interface. Most of the currently employed organic HTL (e.g., Spiro-OMeTAD) are supposed to contribute to the perovskite decomposition and to be responsible for charge recombination processes and polarization barriers. On the other hand, power conversion efficiencies (PCEs) of DSCs are still too low to compete with other conversion technologies. Tandem cells are built by assembling p-type and n-type DSCs in a cascade architecture and, since each dye absorbs on a different portion of the solar spectrum, the harvesting window is increased and the theoretical efficiency limit for a single chromophore (i.e., the Shockley–Queisser limit) is overcome. However, such a strategy is hindered by the lack of a p-type semiconductor with optimal photocathode features. Nickel oxide has been, by far, the first-choice inorganic p-type semiconductor for both PV technologies, but its toxicity and non-optimal features (e.g., too low open circuit voltage and the presence of trap states) call for alternatives. Herein, we study of three p-type semiconductors as possible alternative to NiO, namely CuI, CuSCN and Cu2O. To this aim, we compare the structural and electronic features of the three materials by means of a unified theoretical approach based on the state-of-the art density functional theory (DFT). We focus on the calculation of their valence band edge energies and compare such values with those of two widely employed photo-absorbers, i.e., methylammonium lead iodide (MAPI) and the triple cation MAFACsPbBrI in PSCs and P1 and Y123 dyes in DSCs, given that the band alignment and the energy offset are crucial for the charge transport at the interfaces and have direct implications on the final efficiency. We dissect the effect a copper vacancy (i.e., intrinsic p-type doping) on the alignment pattern and rationalize it from both a structural and an electronic perspective. Our data show how defects can represent a crucial degree of freedom to control the driving force for hole injection in these devices.

Direct Solution Processed Ag(Bix,Sb1−x)S2 Films with Tunable Bandgap for Planar Heterojunction Solar Cells

Silver bismuth antimony sulfide (Ag(Bix,Sb1−x)S2, 0 ≤ x ≤ 1) is considered as a promising light‐harvesting material for solar cell applications because of its excellent stability, abundant element storage, and tunable bandgap. However, the method for depositing the Ag(Bix,Sb1−x)S2 film hasn't been developed, which hinders the investigation of the composition‐dependent photoelectric properties, such as bandgap, band position tunability, and photovoltaic characteristics. In order to apply Ag(Bix,Sb1−x)S2 in photovoltaics, the authors report a convenient solution method to prepare Ag(Bix,Sb1−x)S2 films with continuously tunable constituents through varying the ratio of Bi and Sb in the solution. The bandgaps of Ag(Bix,Sb1−x)S2 films can be turned from 1.70 to 1.22 eV through changing the Bi/Sb ratio. Moreover, for the first time, the authors confirm that Ag(Bix,Sb1−x)S2 can be applied in solar cell applications. Upon device optimizing, the device based on Ag(Bix,Sb1−x)S2 (x = 0.4) shows a champion power conversion efficiency of 2.70%. This research provides an effective method for fabricating Ag(Bix,Sb1−x)S2 films with regulating the bandgap and confirms the photovoltaic application of Ag(Bix,Sb1−x)S2.

The tunable electronic structure and optical properties of vacancy-ordered double perovskites Tl2PdBrxCl6-x (x = 0, 2, 4, 6)

Double perovskites show excellent stability and suitable band gaps, which are superior materials for solar cell applications. In this work, the structure, electronic, and optical properties of vacancy-ordered double perovskites Tl2PdBrxCl6-x (x = 0, 2, 4, 6) are explored by first-principles calculations. The tunable band gaps of the studied compounds are in the range of 1.3–2.2 eV. The band gap is narrowed from Tl2PdCl6 to Tl2PdBr6. Moreover, the band gap of Tl2PdCl6 can be adjusted to the appropriate band gap value through minor Br doping. High concentration of Br doping results in a small band gap variation. The visible light absorption capacity is significantly enhanced from Tl2PdCl6 to Tl2PdBr6. The results show that three compounds including Tl2PdBr2Cl4, Tl2PdBr4Cl2, and Tl2PdBr6 are promising materials for potential optoelectronic applications.

Hydrogen Titanate H2TiO3 Nanowires Derived from K2TiO3 as Potential Materials for Solar Cell Applications: A Theoretical Study

AbstractOne‐dimensional systems of titanium dioxide and titanates are interesting for the fundamental study of physical and chemical properties at the nanoscale. In this work we present the electronic structure, mechanical and optical properties of angstrom scale titanate derived nanowires (ASW) by means of density functional theory (DFT) and Density Functional based Tight Binding (DFTB). This one‐dimensional H2TiO3 nanostructure is an interesting real material that could serve for understanding, at a fundamental level, the physical properties of TiO5 concatenated polyhedrons derived from hydrogen titanates. The proposed structural model demonstrates to be locally stable according to phonon analysis, and it can be inferred that the one‐dimension structure is essentially preserved. The mechanical properties put this nanowire as a flexible material, that could be used in flexible substrates maintaining its electronic properties. Also, the capacity of this system to be sensitized with a catechol dye was explored. For this porpoise, the adsorption of the catechol molecule was tested showing that the most stable interaction corresponds to a dissociative chelate configuration. Finally, it was possible to verify the capability of the sensitized system for injecting electrons from the catechol dye to the nanowire under visible light exposure. Thus, we present these extreme one‐dimensional nanostructured materials as candidates for solar cell applications.

Strain effects on electronic, optical properties and carriers mobility of Cs2SnI6 vacancy‐ordered double perovskite: A promising photovoltaic material

AbstractPerovskite halides have attracted substantial attention as materials for solar cell applications because of their fascinating optoelectronic and photovoltaic properties. We report the results of the first‐principles calculations of the strain effects on electronic and optical properties and carrier mobility of vacancy‐ordered Cs2SnI6 double perovskite. The calculated band gap energy of unstrained Cs2SnI6 is about 1.257 eV when using the Tran‐Blaha modified Becke Johnson (mBJ) exchange potential, which is in good agreement with experimental measurements. Under the applied strains, the energy band gap value increases up to 1.316 eV for −4% compressive strain and decreases to 1.211 eV for 4% tensile strain. This effect is mainly due to the fact that the conduction band minimum shifts under compressive and tensile strains. Based on carrier mobility calculations, we notice that under tensile strain the hole and electron carrier mobility diminish, whereas the carrier mobility increases by 16.3% for electrons and by 9.1% for holes under −4% compressive strain. Moreover, data of the calculated optical constants indicate that applied strains can affect the optical properties of Cs2SnI6 perovskite.

(Digital Presentation) Stable Organic Passivated Carbon Nanotube-Silicon Solar Cells with an Efficiency of 22%

The organic passivated CNT/Si solar cell is a new type of low-cost, high-efficiency solar cell, with challenges concerning the stability of the organic layer used for passivation. In this work, the stability of the organic layer is studied with respect to the internal and external (humidity) water content and additionally long-term stability for low moisture environments. It is found that the organic passivated CNT/Si complex interface is not stable, despite both the organic passivation layer and CNTs being stable on their own and is due to the CNTs providing an additional path for water molecules to the interface. With the use of a simple encapsulation, a record power conversion efficiency (PCE) of 22% is achieved and a stable photovoltaic performance is demonstrated. This work provides a new direction for the development of high-performance/lost-cost photovoltaics in the future and will stimulate the use of nanotubes materials for solar cells applications.

Nile red based dye D–π–A as a promising material for solar cell applications

Nile red based dye D–π–A as a promising material for solar cell applications

The path to overcome low efficiency values in SnS solar cells: An overview on the different current recombination mechanisms

SnS semiconductor is currently a potential material for solar cell application. However, this technology has not been able to overcome the efficiency barrier of 5%, being necessary a complete understanding of the limiting factors. In this work, the analysis of the impact of recombination mechanisms namely radiative and non-radiative due to defects at bulk and SnS/CdS interface on the J-V characteristics of SnS/CdS solar cell performed by SCAPS software is presented and discussed in detail for the first time. Additionally, the impact of SnS and CdS layers thickness, series and shunt resistances, the density of defects at SnS bulk material, the density of defects at the interface as well as the concentration of acceptors were studied. Conditions that optimize device performance were also presented. It is demonstrated that the optimization of the device can result in an efficiency promotion from 2.03% to 14.7%.

Optical investigation on pure and Fe, Mn doped lanthanum cobalt oxide (LaCoO3) nanoparticle

The Absorption of incident wave can induce a variety of transitions amongst bands and sub bands that leads to the appearance of absorption peaks in the absorption spectra. UV absorption spectroscopy helps to investigate the optical properties of Nano sized particles such as LaCoO3, Fe doped LaCoO3 and Mn doped LaCoO3. For pure LaCoO3 nanoparticle, 207.49nm was the highest absorbance and there is a sudden decrease in absorbance at 245.67nm. While adding the Fe and Mn dopant into LaCoO3, the absorbance increases. For Fe doped LaCoO3 the highest absorbance is at 345.88nm and for Mn doped LaCoO3 has absorbance at 209.68nm. For pure LaCoO3 the band gap is 2.582. By adding dopant Fe into LaCoO3, the band gap decreases into 1.755 and for Mn doped LaCoO3, the band gap is 1.904. Band gap decreases due to the increase in the particle size. Hence, it is useful material for solar cell applications.

First example of vinylbenzene based small photovoltaic molecules: Towards the development of efficient D-π-A configured optoelectronic materials for bulk heterojunction solar cells

Making contribution to the development of novel photovoltaic materials for solar cell applications, we rationally developed six novel vinylbenzene based planar donor-π-acceptor (D-π-A) compounds. Optoelectronic properties of developed molecules are determined using frontier molecular orbital (FMO), UV–Visible, density of state (DOS), transition density matrix (TDM) heat map, open circuit voltage (Voc), binding energies (E b ), reorganization energy of electron ( λ e ), hole ( λ h ), charge transfer analysis and compared with reference DVB-T-ID. Donor group modifications effectively contributed to augment photovoltaic features in all developed compounds. Developed molecules are found with reduced energy gap (2.566–1.805 eV), broaden absorption wavelength (548.09–800.36 nm) and small transition energy (2.262–1.549 eV) as compared to reference DVB-T-ID values 2.819 eV, 492.84 nm and 2.515 eV respectively. The developed molecules have proficient hole and electron transfer mobilities and can serve as best candidate when blended with PC 61 BM film. Optoelectronic features of all developed molecules especially D5 is ascertained eye-catching as compared to DVB-T-ID , hence recommended for future solar cell applications. • Six vinylbenzene based planar D-π-A photovoltaic compounds are designed by donor group modifications. • The optoelectronic properties were studied in detail using DFT and TDDFT calculations. • FMO, UV–Visible, DOS, ODOS, TDM, Voc, reorganization energy of electron and hole, binding energy and charge transfer analysis are performed. • All vinylbenzene based investigated molecules exhibited remarkable optoelectronic properties. • Investigated molecules are recommended for future solar cell applications.

Two-Dimensional Cs3Sb2I9-xClx Film with (201) Preferred Orientation for Efficient Perovskite Solar Cells.

All-inorganic Sb-perovskite has become a promising material for solar cell applications owing to its air stability and nontoxic lead-free constitution. However, the poor morphology and unexpected (001) orientation of Sb-based perovskite films strongly hinder the improvement of efficiency. In this work, two-dimensional Cs3Sb2ClxI9−x with (201) preferred orientation has been successfully fabricated by introducing thiourea (TU) to the precursor solution. The presence of the C=S functional group in TU regulates the crystallization dynamics of Cs3Sb2I9−xClx films and generates the (201) preferred orientation of Cs3Sb2ClxI9−x films, which could effectively improve the carrier transport and film morphology. As a result, the Cs3Sb2I9−xClx perovskite solar cells (PSCs) delivered a power conversion efficiency (PCE) of 2.22%. Moreover, after being stored in nitrogen at room temperature for 60 days, the devices retained above 87.69% of their original efficiency. This work demonstrates a potential pathway to achieve high-efficiency Sb-based PSCs.

Performance evaluation and optimization of CH3NH3PbBr3 based planar perovskite solar cells using various hole-transport layers

Metal halide perovskites are promising absorber materials for solar cell applications due to (i) low-cost processing methods, and (ii) cell efficiency is comparable to the standard silicon solar cells. Methylammonium lead bromide (CH3NH3PbBr3) is a metal halide perovskite having wide band gap suitable for high open-circuit voltage (Voc) solar cell. Here we report the performance of CH3NH3PbBr3 based solar cells by using various hole-transport layers (HTLs) independently with titanium dioxide (TiO2) as electron transport layer (ETL). Spiro-OMeTAD was used as HTL in the control device. Absorbance study indicates the band gap of CH3NH3PbBr3 is around 2.25 eV. Energy band alignment shows the superior band alignment across the device when copper thiocyanate (CuSCN) is used. Short-circuit current density (Jsc) is independent of electrode work functions. However, Jsc depends upon internal reflection at the absorber/HTL interface and reflection is high for CuSCN and low for nickel oxide (NiO). Our result shows that fill factor and efficiency depends on absorber thickness, top and bottom electrode work functions. For Ohmic contact, top electrode and bottom electrode work functions must be between −4.0 eV to −4.4 eV and −4.9 eV to −5.26 eV respectively and device performs excellent in these regimes. For the control device, Voc, Jsc, fill factor, and efficiency of 2.10 V, 9.64 mA/cm2, 0.90, and 18.42% were obtained. Whereas for the cell having CuSCN as HTL, a high efficiency of 23.39% with Voc of 2.10 V, Jsc of 13.04 mA/cm2, and fill factor of 0.85 were obtained.