Solar Cell Applications Research Articles

Slow-Release Effect Assisted Crystallization for Sequential Deposition Realizes Efficient Inverted Perovskite Solar Cells.

The two-step sequential deposition strategy has been widely recognized in promoting the research and application of perovskite solar cells, but the rapid reaction of organic salts with lead iodide inevitably affects the growth of perovskite crystals, accompanied by the generation of more defects. In this study, the regulation of crystal growth was achieved in a two-step deposition method by mixing 1-naphthylmethylammonium bromide (NMABr) with organic salts. The results show that the addition of NMABr effectively delays the aggregation and crystallization behavior of organic salts; thereby, the growth of the optimal crystal (001) orientation of perovskite is promoted. Based on this phenomenon of delaying the crystallization process of perovskite, the "slow-release effect assisted crystallization" is defined. Moreover, the incorporation of the Br element expands the band gap of perovskite and mitigates material defects as nonradiative recombination centers. Consequently, the power conversion efficiency (PCE) of the enhanced perovskite solar cells (PSCs) reaches 20.20%. It is noteworthy that the hydrophobic nature of the naphthalene moiety in NMABr can enhance the humidity resistance of PSCs, and the perovskite phase does not decompose for more than 3000 h (30-40% RH), enabling it to retain 90% of its initial efficiency even after exposure to a nitrogen environment for 1200 h.

Physiochemical and electrical activities of nano copper oxides synthesised via hydrothermal method utilising natural reduction agents for solar cell application

Abstract The aim of this study is to explore the potential compatibility of copper oxide nano-powders synthesised via hydrothermal method for solar cell applications by triggering a reaction between copper acetate and various reducing agents derived from natural resources, including Arabic gum, molasses, starch, and vinegar. X-ray diffraction analysis revealed the crystalline phases of the synthesised materials, indicating the successful synthesis of copper oxide material, which was confirmed by identifying patterns that matched specific copper oxide phases. Fourier transform infrared spectroscopy was employed to analyse the molecular vibrations and chemical compounds present in the reducing agents. The reducing properties of the selected materials and their capacity to convert copper acetate into copper oxide were validated. Field-emission microscopy and transmission electron microscopy analyses of the synthesised copper oxide nanoparticles (NPs) revealed variations in particle size and morphology. These variations were dependent on the particular reducing agent utilised during synthesis. Moreover, the carrier concentration, mobility, and resistivity were evaluated as the electrical properties of the spin-coated copper oxide thin films. Hall effect analysis determined that the choice of reducing agent significantly influenced the carrier concentration (n) and mobility (µ) of the films. Remarkably, nano copper oxide films synthesised using starch exhibited irregular spherical grains with porous surfaces. Starch-synthesised samples showed the highest conductivity of n = 1.2 × 1019 cm−3 when compared with those synthesised with other reducing agents. This suggests that the porous surfaces in the starch-synthesised films may have contributed to their enhanced conductivity compared to films synthesised with alternative reducing agents. In summary, the findings emphasised the influence of the reducing agent on the size, morphology, and electrical conductivity of the copper oxide NPs.

Electrochemical analysis of hydrothermally synthesized 2D/1D WS2/WO3 nanocomposites for solar cell application

The nanocomposites of transition metal dichalcogenides (TMDs) and metal oxides (MOs) show enhanced properties for photovoltaic applications. In view of this, we have reported the synthesis of a series of tungsten sulphide/tungsten oxide (WS2/WO3) nanocomposites, wherein tungsten to sulphur ratio has been gradually varied to achieve the optimized properties for photovoltaic applications. The samples were analysed for structural, optical, morphological, microstructural, electrokinetic and electrochemical properties by various characterization techniques. Integrating the properties of WS2 and WO3 provided enhanced properties in the form of wider absorbance range, optimized band gap, better colloidal stability and reduced charge transfer resistance. The as-synthesized nanocomposites showed the absorbance in UV & visible regions with the band gap varying from 1.54 eV to 1.68 eV. The zeta potential measurement showed high colloidal stability of some of the nanocomposites with values < −30 mV along with their uniform distribution. The electrochemical behaviour of the samples has been studied by cyclic voltammetry and potentio electrochemical impedance spectroscopy in which prominent redox peaks and diffusive behaviour have been observed. The impedimetric properties revealed the presence of Warburg diffusion which shows their suitability for photovoltaic applications. The sample with least sulphur to tungsten molar ratio was observed to have lowest charge transfer resistance and highest exchange current density of 198.8 μA. The samples with molar ratio nearly unity have high charge transfer resistance and low exchange current density. The present work reveals that the optical, electrokinetic and electrochemical properties of WS2/WO3 nanocomposites can be optimized for solar cell application by controlling the precursors’ concentration.

Theoretical screening of N-[5'-methyl-3'-isoxasolyl]-N-[(E)-1-(-2-thiophene)] methylidene]amine and its isoxazole based derivatives as donor materials for bulk heterojunction organic solar cells: DFT and TD-DFT investigation.

In the present work, the influence of aromatic ring substitution on a series of small-donor organic molecules (A, B, C, D, and E) with isoxazole cores was investigated for photovoltaic applications in organic solar cells. Frontier molecular orbital analysis, chemical reactivity descriptors, dipole moment, and population analysis showed that all the organic materials have intramolecular charge transfer abilities capable of donating electrons to the acceptor material (PCBM). The required photovoltaic parameters such as Voc, FF, Jsc, LHE, and other associated optoelectronic parameters are reported. The results demonstrate that aromatic ring substitution influences charge transfer and power conversion efficiencies of solar cells. That is, an increase in the aromatic character of a material increases its charge transfer, and as a result, its photovoltaic properties are increased. Additionally, all the investigated derivatives are good charge transporters with suitable electron reorganization energies, which are beneficial for minimizing energy loss. Hence, these organic derivatives with isoxazole backbones are promising materials and may provide fresh insights into the design of new materials for organic solar cell applications. All calculations were performed using DFT and the ORCA 4.1.0 program package as the main tool for geometry optimization and frequency calculations. The Avogadro 1.2.1 visualization tool was used to prepare all input files executed by ORCA 4.1.0. The BP86, B3LYP, and wB97M series of functionals coupled with the def2/TZVP basis set were employed for geometry optimization. All energy-related calculations were carried out using the M06-2x functional. Multiwfn version 3.7 was used for aromaticity and population analysis. Excited state and UV-visible spectra were simulated using the TD-DFT method at the CAM-B3LYP-D3, wB97X-D3, and PBE0-D3 coupled with the ma-def2-TZVP basis set. Moreover, solvent effects were incorporated using the SMD scheme as incorporated in the ORCA software. Lastly, the RIJCOSX approximations were used to speed up calculations while maintaining accuracy.

Active Passivation of Anion Vacancies in Antimony Selenide Film for Efficient Solar Cells.

Binary antimony selenide (Sb2Se3) is a promising inorganic light-harvesting material with high stability, nontoxicity, and wide light harvesting capability. In this photovoltaic material, it has been recognized that deep energy level defects with large carrier capture cross section, such as VSe (selenium vacancy), lead to serious open-circuit voltage (VOC) deficit and in turn limit the achievable power conversion efficiency (PCE) of Sb2Se3 solar cells. Understanding the nature of deep-level defects and establishing effective method to eliminate the defects are vital to improving VOC. In this study, a novel directed defect passivation strategy is proposed to suppress the formation of VSe and maintain the composition and morphology of Sb2Se3 film. In particular, through systematic study on the evolution of defect properties, the pathway of defect passivation reaction is revealed. Owing to the inhibition of defect-assisted recombination, the VOC increases, resulting in an improvement of PCE from 7.69% to 8.90%, which is the highest efficiency of Sb2Se3 solar cells prepared by thermal evaporation method with superstrate device configuration. This study proposes a new understanding of the nature of deep-level defects and enlightens the fabrication of high quality Sb2Se3 thin film for solar cell applications.

Nanoarchitectonics of lead-free 2D cobalt-based diammonium hybrid for perovskites solar cell applications

Nanoarchitectonics of lead-free 2D cobalt-based diammonium hybrid for perovskites solar cell applications

Synthesis, characterization, and effective removal of dye pollutants from water bodies using a new ZnO nanocomposite

Biogenic zinc oxide nanocomposites were fabricated through an eco-friendly method by employing Boerhaavia diffusa leaf extract in combination with zinc nitrate. The nanocomposites underwent a comprehensive characterization process involving uv–visible spectroscopy (UV-DRS), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), selected area diffraction (SAED), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDAX), high-resolution transmission electron microscopy (HRTEM), inductively coupled plasma mass spectrometry (ICP-MS), X-ray fluorescence (XRF), and zeta potential studies. The XRD analysis substantiated the existence of a ZnO nanocomposite possessing a hexagonal wurtzite crystalline structure. Furthermore, extended rod-shaped formations were identified in conjunction with clusters of sodium and potassium.The effectiveness of the ZnO nanocomposite in photocatalytic degradation was assessed for various types of dyes: cationic and anionic like Methylene Blue (MB), Malachite Green (MG), Congo Red (CR), and Methyl Orange (MO) in aqueous medium. The nanocomposites demonstrated remarkable photodegradation capabilities for both cationic and anionic dyes. Notably, 50 mg of the catalyst effectively removed Congo Red (15 ppm) and Methylene Blue (15 ppm) within 40–60 min under direct sunlight and 15–30 min under UV illumination. The samples are more active on UV light illumination rather than exposure to sunlight due to.the favorable semiconductor band gap (3.26 eV). As a result, this research suggests an uncomplicated, budget-friendly, and environmentally sustainable approach for manufacturing a ZnO-based photocatalyst. Moreover, the inclusion of potassium and sodium elements in the nanocomposite showcased a beneficial synergistic impact on its photoactivity. This necessitates additional scrutiny for its potential application in treating diverse organic pollutants in water resources. Additionally, high efficiency of the catalyst under direct sunlight holds potential for applications in solar cells.

Strain engineering of electronic, mechanical, and optical properties of orthorhombic III–V group monolayers by first principles calculations

Using first principles calculations, we systematically investigated the effects of strain engineering on the electronic, mechanical, and optical properties of two-dimensional (2D) orthorhombic III–V group materials, including BN, BP, BAs, AlN, AlP, and GaN. It is shown that all the III–V orthorhombic monolayers exhibit excellent mechanical anisotropy for Young’s modulus, Shear modulus, and Poisson’s ratio, especially for the AlN and GaN monolayers. AlN, AlP, and GaN are predicted to be indirect bandgap semiconductors, with their bandgap of 0.70, 0.15, and 0.53 eV, respectively. And BN is demonstrated to be a direct bandgap semiconductor (0.63 eV). Under uniaxial tensile strains, their electronic structures have non-monotonic anisotropic variations and these monolayers can be effectively modulated from metal to semiconductor, experiencing indirect–direct bandgap transitions. In addition, all the orthorhombic III–V materials exhibit highly anisotropic light-harvesting performances and the optical absorbance can be efficiently tailored with tensile strains applied along a- and b-directions. The strong optical absorptions in the visible light regions suggested that AlN, BN, and GaN may be optically tunable 2D materials for component absorbance layers for solar cell applications. The excellent anisotropic and tunable electronic, mechanical, and optical performances indicate that the orthorhombic III–V monolayers are promising candidates for potential applications of optoelectronics and photovoltaics.

The investigation of alternative metals of Au, Ag, Al, and Cu for back contact used in fabricated ZnS/SnS heterojunction for solar cell application

The investigation of alternative metals of Au, Ag, Al, and Cu for back contact used in fabricated ZnS/SnS heterojunction for solar cell application

Ab initio study of the physical characteristics of CsPb1-xMoxBr3 perovskites

Doped CsPbBr3 perovskites are recently in great interest because of their potential in tandem solar cell applications. In this study, the structural, electronic, magnetic, thermoelectric, and optical properties of CsPb1-xMoxBr3 (x=0, 0.25, 0.5, 0.75) cubic phase perovskites are investigated by using density functional theory and semi-classical Boltzmann transport theory. The trend of the lattice parameters decreases with increasing the Mo concentration, which corresponds to Vegard's law. The stability of all studied compounds is proved by estimating the cohesive energy and phonons frequency modes at Γ points. There is no certain trend in band gap variation, but the minimum band gap (1.386 eV PBE or 1.872 eV mBJ) has occurred at x=0.5. The values of the absorption coefficient are slightly significant near the infrared region for Mo-doped compounds and this could make them promising candidates in infrared applications. Furthermore, the spin-polarized DOS revealed their ferromagnetic half-metal behavior. The figure of merit at spin-up at room temperature is close to 1.0 for doped compounds.

Exploring the potential of green synthesized ZnO-SnO2 composite as an effective electron transport layer for perovskite solar cells: A sustainable approach

Utilizing green-synthesized ZnO nanoparticles as an electron transport layer (ETL) is a key strategy in perovskite solar cell applications, leveraging their high electron mobility, conductivity, stability against photo-corrosion, and cost-effectiveness. In this study, these environmentally synthesized nanoparticles, combined with SnO2, formed a composite solution-processed ETL achieving an impressive 18.09 % device efficiency, with 1.06 V open circuit voltage, 71.71 % fill factor, and 23.80 mA/cm2 short circuit current density. These values underscore the composite material's potential for device applications. Additionally, capacitance measurements investigated ETL and absorber layer interfaces, yielding crucial insights into their behaviour under varying voltage, frequency, and illumination conditions. The study highlights the ZnO-NP and SnO2 composite's efficacy as a superior ETL in PSCs, emphasizing the environmental sustainability implications of employing green-synthesized materials in solar energy technologies.

AlZnO magnetron sputtered thin film for photovoltaic application

Aluminum zinc oxide (AZO) is a nontoxic and a low-cost material that finds application as a transparent conducting electrode in photovoltaic devices. In this study the (direct current) DC magnetron sputtering of AZO films is carried out at different deposition times of 5, 10, 15, 20 and 25 min’s at room temperature and it’s structural, optical, electrical and morphological properties are studied for its use as a front contact for thin film solar cell application. The structural study suggests that the preferred orientation of grains along (002) plane having hexagonal structure and the optical and the electrical studies suggest that the films show an average transmission of 70% and a resistivity of the order of 10-4Ωcm. On the other hand, the scanning electron microscopy (SEM) images suggest the formation of packed grains having a homogeneous surface. Moreover in order to study the optoelectronic properties of prepared samples, the electronic and optical calculations of the AZO are performed by the first-principles calculations using density functional theory (DFT).

Multi-objective-Global-Optimization-Approach Predicted Quasi-Layered Ternary TiOS Crystals with Promising Photocatalytic Properties

Abstract Titanium dioxide (TiO2) has attracted considerable research attentions for its promising applications in solar cells and photocatalytic devices. However, the intrinsic challenge lies in the relatively low energy conversion efficiency of TiO2, primarily attributed to the substantial band gaps (exceeding 3.0 eV) associated with its rutile and anatase phases. Leveraging multi-objective global optimization, we have identified two quasi-layered ternary Ti-O-S crystals, composed of titanium, oxygen and sulfur. The calculations of formation energy, phonon dispersions, and thermal stability confirm the chemical, dynamical and thermal stability of these newly discovered phases. Employing the state-of-art hybrid density functional approach and many-body perturbation theory (quasiparticle GW approach and Bethe-Salpeter equation), we calculate the optical properties of both the TiOS phases. Significantly, both phases show favorable photocatalytic characteristics, featuring band gaps suitable for visible optical absorption and appropriate band alignments with water for effective charge carrier separation. Therefore, ternary compound TiOS hold the potential for achieving high-efficiency photochemical conversion, showing our multi-objective global optimization provides a new approach for novel environmental and energy materials design with multicomponent compounds.

Synthesis, Characterization, and Applications of Carbon Dots for Determination of Pharmacological and Biological Samples: A Review.

Carbon dots (CDs) are a novel category of carbon-based nanomaterials characterized by their small size, often less than 10 nm. CDs physical, chemical, and optical properties can be tuned using one-pot assembly. Because of their non-toxicity, biocompatibility, chemical and physical responsiveness, photo- and chemical-bleaching resistance, and low cost, nanoparticles have become incredibly versatile. They find various applications in detecting inorganic substances, bio sensing, visualizing cells, studying biological processes in live cells, and aiding in medication delivery. Additionally, CDs exhibit versatility in electronics and energy storage, making them promising candidates for applications in solar cells, light-emitting diodes, and supercapacitors. CDs are more photo stable for hours than typical fluorescent semiconductor quantum dots. Before applying CDs, they must be characterized. Techniques such as UV-VIS spectroscopy, fluorescence spectrophotometry, FT-IR, TEM, XRD, Raman spectroscopy, and NMR are commonly used to assess their photophysical and structural properties. This article review explores the synthesis, characterization applications of CDs in analytical techniques for the determination of various analytes. The article provides a detailed analysis of the different methodologies used to make nanomaterials and devices for the characterization of CDs. It also discusses the challenges that arise when using CDs in analytical techniques for detecting different analytes. The focus of this review is on accurately determining pharmaceutical and biological samples using CDs as sensing probes.

Band gap tuning of perovskite solar cells for enhancing the efficiency and stability: issues and prospects.

The intriguing optoelectronic properties, diverse applications, and facile fabrication techniques of perovskite materials have garnered substantial research interest worldwide. Their outstanding performance in solar cell applications and excellent efficiency at the lab scale have already been proven. However, owing to their low stability, the widespread manufacturing of perovskite solar cells (PSCs) for commercialization is still far off. Several instability factors of PSCs, including the intrinsic and extrinsic instability of perovskite materials, have already been identified, and a variety of approaches have been adopted to improve the material quality, stability, and efficiency of PSCs. In this review, we have comprehensively presented the significance of band gap tuning in achieving both high-performance and high-stability PSCs in the presence of various degradation factors. By investigating the mechanisms of band gap engineering, we have highlighted its pivotal role in optimizing PSCs for improved efficiency and resilience.

Designing simple non-fused terthiophene-based electron acceptors for efficient organic solar cells

Low-cost photovoltaic materials are essential for realizing large-scale commercial applications of organic solar cells (OSCs). However, highly efficient OSCs based on low-cost photovoltaic materials are scarce due to a deficiency in understanding the structure-property relationship. Herein, we investigated two low-cost terthiophene-based electron acceptors, namely, 3TC8 and 3TEH, with 3,4-bis(octan-3-yloxy)thiophene, differing only in the alkylated thiophene-bridges. Both acceptors exhibit low optical gaps (∼1.43 eV) and possess deep highest occupied molecular orbital (HOMO) levels (∼−5.8 eV). Notably, the single-crystal structure of 3TEH demonstrates highly planar conjugated backbone and strong π-π stacking between intermolecular terminal groups, attributed to the presence of the bulky alkylated noncovalently conformational locks. Upon utilizing both acceptors to fabricate OSCs, the 3TC8-based device exhibited a power conversion efficiency (PCE) of 11.1%, while the 3TEH-based OSC demonstrated an excellent PCE of 14.4%. This PCE is the highest among OSCs based on terthiophene-containing electron acceptors. These results offer a new strategy for designing low-cost electron acceptors for highly efficient OSCs.

Heterojunction interface engineering of C60 electron transport layer insertion enables efficient Cd-free Sb2Se3 solar cells

Antimony selenide (Sb2Se3) emerges as a promising semiconductor for solar energy conversion, attributed to its high light absorption and excellent photoelectric properties, coupled with notable stability and consistent stoichiometry. Yet, its application in thin-film solar cells is limited by non-radiative recombination losses at suboptimal heterojunction interfaces. Addressing this, we propose a strategy employing a C60 electron transport layer (ETL), thermally evaporated between the Sb2Se3 absorber and SnOx buffer layer. This approach not only increases the carrier density in SnOx but also passivates harmful defects like VO and OH−, thus reducing interfacial recombination. Incorporating C60 ETL improves the fill factor (FF) and open-circuit voltage (VOC) of the Sb2Se3 device, achieving a maximum power conversion efficiency (PCE) of 6.65 %. This finding highlights the significance of ETL-dependent interfacial engineering in enhancing Sb2Se3 solar cell performance, offering a novel and accessible solution to the primary challenge in developing Cd-free Sb2Se3 solar cells.

Preparation and characterization of TiO2 nanostructures by changing the parameters of trichloroaniline concentration, pH and annealing for dye-sensitized solar cell application

Preparation and characterization of TiO2 nanostructures by changing the parameters of trichloroaniline concentration, pH and annealing for dye-sensitized solar cell application

Excited-State Dynamics of MAPbBr3: Coexistence of Excitons and Free Charge Carriers at Ultrafast Times.

Methylammonium lead tribromide perovskite (MAPbBr3) is an important material, for example, for light-emitting applications and tandem solar cells. The relevant photophysical properties are governed by a plethora of phenomena resulting from the complex and relatively poorly understood interplay of excitons and free charge carriers in the excited state. In this study, we combine transient spectroscopies in the visible and terahertz range to investigate the presence and evolution of excitons and free charge carriers at ultrafast times upon excitation at various photon energies and densities. For above- and resonant band-gap excitation, we find that free charges and excitons coexist and that both are mainly promptly generated within our 50-100 fs experimental time resolution. However, the exciton-to-free charge ratio increases upon decreasing the phonon energy toward resonant band gap excitation. The free charge signatures dominate the transient absorption response for above-band-gap excitation and low excitation densities, masking the excitonic features. With resonant band gap excitation and low excitation densities, we find that although the exciton density increases, free charges remain. We show evidence that the excitons localize into shallow trap and/or Urbach tail states to form localized excitons (within tens of picoseconds) that subsequently get detrapped. Using high excitation densities, we demonstrate that many-body interactions become pronounced and effects such as the Moss-Burstein shift, band gap renormalization, excitonic repulsion, and the formation of Mahan excitons are evident. The coexistence of excitons and free charges that we demonstrate here for photoexcited MAPbBr3 at ultrafast time scales confirms the high potential of the material for both light-emitting diode and tandem solar cell applications.

Influence of annealing temperature on nano crystalline description for CuZnS thin films

Copper Zinc Sulphide (Cu0.5Zn0.5S) alloy and thin films were fabricated in a vacuum. Nano crystallized (CZS) film with thick 450±20 nm was deposit at substrates glasses using thermal evaporation technique below ~ 2 × 10− 5 mbar vacuum to investigated the films structural, morphological and optical properties depended on annealing temperatures ( as-deposited, 423, 523 and 623) K for one hour. The influences annealed temperature on structurally besides morphologically characteristics on these films were investigated using XRD and AFM respectively. XRD confirms the formation a mixed hexagonal phase of CuS-ZnS in (102) direction with polycrystalline in nature having very fine crystallites size varying from (5.5-13.09) nm. AFM analysis shows the uniform distribution of closely packed grains, grain size for that film diverge on ranges as of (52.37 to 89.25) nm after annealed. The optical properties of all films prepared had been examined for the wavelength range 400 - 1000 nm using UV-Vis-NIR spectrometer. The band gaps of (Cu0.5Zn0.5S) films are obtained in the range of 2.4 to 1.9 eV, which makes it a suitable absorber as well as buffer/window layer for solar cell applications.