High-efficiency Solar Cell Applications Research Articles

Mapping Spatial Strain Distribution and Its Effects on Optoelectronic Properties in Wrinkled Perovskite Films.

Organic-inorganic halide perovskite films, fabricated by using the antisolvent method, have garnered intense attention for their application in high-efficiency and stable solar cells. These films characteristically develop periodic wrinkled microstructures. Previous research has indicated that macroscopic residual strain significantly influences the optoelectronic behaviors of these films. However, the detailed interplay between the wrinkled morphology, strain distribution, and local photophysical properties at the micro- and nanoscale has not been fully elucidated. Here, we explore the microscopic morphology-strain-property relationship within wrinkled perovskite films employing correlative micro-optical and nanoelectrical microscopy techniques. Microphotoluminescence (PL) mapping supplemented by in situ strain PL measurements identifies a heterogeneous spatial strain distribution across the microstructural hills and valleys. Additionally, light-intensity-dependent photoconductive atomic force microscopy reveals that valleys experiencing less compressive strain exhibit a lower conductivity and a higher propensity for ion migration. The findings underscore the potential of targeted strain engineering to optimize the performance and longevity of perovskite solar cells.

Formulation of optimized TCA using PDMS epoxy and Ag-coated PMMA for high-efficiency Si tandem solar cell applications

In this study, we aimed to develop and characterize Transparent Conductive Adhesive (TCA) materials for mechanically stacked tandem solar cell applications. The research objectives were to enhance the transparency, conductivity, and adhesive strength of TCAs to improve the efficiency and practicality of tandem solar cells. The TCA formulation comprises a combination of polymers and Ag-coated particles, with flexible poly-methyl methacrylate (PMMA) micro-spheres serving as conductive particles and SYLGARD 184 silicon elastomer poly-di-methyl-siloxane (PDMS), mixed in a 10:1 ratio of base to curing agent, serving as the transparent adhesive. We conducted systematic experiments with Ag-particle coverage areas ranging from 0.34 % to 21.61 % at temperatures of 80 °C and 100 °C, under 500 mb pressure. The optimal conductivity was achieved at 2 wt% Ag-particle coverage, measuring 5.26 × 10⁷ S/m, with over 93 % transparency. These key results indicate the significant potential of the optimized TCA in enhancing the performance of mechanically stacked tandem solar cells, thus contributing to the advancement of renewable energy technologies.

Electric field tunable electronic structures and ultrahigh power conversion efficiency of BC6N/MoSe2 van der Waals heterostructure: A promising material for high-efficiency solar cell applications

A novel BC6N/MoSe2 van der Waals heterostructure (vdWH) was fabricated by stacking monolayer BC6N onto monolayer MoSe2. The structural stability, electronic structure, optical properties, and power conversion efficiency (PCE) of the BC6N/MoSe2 vdWH were systematically investigated using first-principles calculations and by considering the effects of electric fields. The results indicated that the stable BC6N/MoSe2 vdWH has an indirect band gap of 1.84 eV, and exhibits a type II band alignment which is not affected by external electric fields. Additionally, the band gap of BC6N/MoSe2 decreased linearly with increasing intensity of the electric field, and the maximum band gap was 1.88 eV under an electric field of −0.05 V/Å. The optical absorptivity of the BC6N/MoSe2 vdWH increased in the visible region, with the highest optical absorptivity (23.1 %) observed in the violet region. The BC6N/MoSe2 vdWH displayed an ultrahigh PCE (22.9 %), which reached 23.6 % under an electric field of −0.05 V/Å. The PCE decreased with increasing intensity of the electric field, but was still high (19.1 %) under an electric field of 0.2 V/Å. The optimal optical absorptivity and ultrahigh and tunable PCE of the BC6N/MoSe2 vdWH indicate its great potential for application as high-efficiency solar cell materials.

Optimization of vertical gradient Pb-Sn hybrid perovskite solar cells using SCAPS (Solar Cell Capacitance Simulator)

Lead-tin hybrid perovskite solar cells emerge as a promising alternative to traditional lead-based cells, addressing environmental and stability concerns, however their efficiency lags. During the fabrication of lead-tin mixed perovskites, the Pb/Sn ratio varies across the film due to different solubilities under various processing conditions. To tackle this issue, we propose a novel perovskite absorber with a vertical gradient in the lead-tin ratio. Our study employs SCAPS-1D simulations to investigate the performance of ITO/HTL/gradient perovskite/ETL/Ag cell structures with different transport layer materials. We systematically analyze the impact of doping levels, defect density states, and interfacial defects in the absorber layer on device efficiency. Through optimization of the device structural parameters, reflecting real experimental conditions, we achieved an energy conversion efficiency of 24.84%. This efficiency is comparable to that of lead-based perovskite solar cells. Interestingly, simulations suggest that omitting the electron transport layer still yields an efficiency above 23.5%, potentially simplifying the fabrication process. This finding indicates that vertically graded Pb-Sn hybrid perovskite solar cells hold great promise for high-efficiency solar cell applications.

High-throughput screening of the transport behavior of tetragonal perovskites.

Halide perovskites have attracted attention due to their low cost and excellent optoelectronic properties. Although their optical properties gained widespread consensus, there was still divergence in understanding carrier transport behavior. In this study, the mobility of tetragonal perovskites was investigated by empirical models, including longitudinal acoustic phonon (LAP) and polar optical phonon (POP) models. The results revealed that the mobility predicted from the LAP model was much higher than that from the POP model. A longitudinal optical phonon (LOP) was considered as the decisive scattering source for charge carriers in perovskites. Furthermore, the mobility was extremely sensitive to z-axis strain, and 8 types of perovskites with high carrier mobility were screened. Using the experimental lattice constants, the predicted mobility of CsSnI3 was μe,z = 1428 and μh,z = 2310 cm2 V-1 s-1, respectively. The tetragonal CsSnI3 has high mobility and moderate bandgaps, suggesting potential applications in high-efficiency solar cells.

Precise synthesis and photovoltaic properties of giant molecule acceptors

Series of giant molecule acceptors DY, TY and QY with two, three and four small molecule acceptor subunits are synthesized by a stepwise synthetic method and used for systematically investigating the influence of subunit numbers on the structure-property relationship from small molecule acceptor YDT to giant molecule acceptors and to polymerized small molecule acceptor PY-IT. Among these acceptors-based devices, the TY-based film shows proper donor/acceptor phase separation, higher charge transfer state yield and longer charge transfer state lifetime. Combining with the highest electron mobility, more efficient exciton dissociation and lower charge carrier recombination properties, the TY-based device exhibits the highest power conversion efficiency of 16.32%. These results indicate that the subunit number in these acceptors has significant influence on their photovoltaic properties. This stepwise synthetic method of giant molecule acceptors will be beneficial to diversify their structures and promote their applications in high-efficiency and stable organic solar cells.

Facile access to C-N bonds via unexpected side reactions of Knoevenagel condensation and their application in high-efficiency organic solar cells

Facile access to C-N bonds via unexpected side reactions of Knoevenagel condensation and their application in high-efficiency organic solar cells

Growth and Exploration of Inorganic Semiconductor Electron and Hole Transport Layers for Low-Cost Perovskite Solar Cells

The perovskite exhibited outstanding performance and was a promising alternative material for a low-cost, high power conversion efficiency (PCE) solar cell application. To avoid the high-cost organic materials as electron transport layers (ETL) and hole transport layers (HTL) in perovskite solar cells (PSCs), here introduce the inorganic semiconductor nanomaterials ZnS and CuS work as an ETL and HTL, respectively. In this work, we selected chalcogenides such as zinc sulfide (ZnS) and copper sulfide (CuS) as the 2-electron and hole transport layers and utilized them for perovskite solar cell application. For the proposed cell structure FTO/ZnS/perovskite (CH3NH3PbI3)/CuS/Ag, the deposition of layers has been achieved via different techniques such as thermal evaporation, spin coating and doctor blade, respectively. X-ray diffraction and Field effect scanning electron microscopy (FESEM) with Energy-dispersive X-ray spectroscopy were used to characterize the structural and morphological properties of the prepared samples. UV-Visible spectrophotometer and current density-voltage curve were used to measure the optical and electrical parameters of the deposited layers, respectively. From the J-V characteristics, for the proposed and fabricated PSCs, the estimated PCE is about 0.28 %, open-circuit voltage (VOC) = 0.29 V, and short-circuit current density (JSC) = 3.96 mA/cm2. The results are good and the inorganic nanomaterial layers used in this study are promising for future studies. HIGHLIGHTS In this study, chalcogenide materials such as zinc sulphide (ZnS) as the electron transport layer and cadmium sulfide (CdS) as the hole transport layer in solar perovskite cell applications were investigated Use easy and simple deposit methods such as chemical bath deposition and doctor blade method The possibility of using chalcogenide materials in the field of perovskite solar cells, although the efficiency of the obtained cell is very small, is an indication of the response of such materials in the application of perovskite solar cells GRAPHICAL ABSTRACT

Morphology and structure of CdCl2-Containing CdTe films deposited by discrete vacuum thermal evaporation

The impact of discrete vacuum thermal evaporation (DVTE)-produced CdTe thin films after thermal annealing and CdCl2 treatment is discussed in the present article. As a result of simultaneous DVTE of CdCl2 and CdTe, CdCl2 was added straightly into the bulk of the formed CdTe film at the 270 °C substrate temperature in a single procedure. The DVTE approach deposits CdTe thin films with a high crystalline structure, which can be utilized effectively for the production of high efficiency solar cell applications, according to the results of X-ray diffraction, scanning electron microscopy with focused ion beam, transmission electron microscopy, and atomic force microscopy measurements.

Comparison of C-, N-, and O-Incorporated Non-blistering PECVD Si Films for Application in SiOx-Based Passivating Contacts for Si Solar Cells

For application in high-efficiency silicon solar cells bearing SiOx-based passivating contacts, we have developed 100 nm thick, PECVD Si-rich amorphous films, capable of being processed in industrial furnaces without blistering, by incorporating adequate amounts of each of C, N, and O in the films during PECVD. We found that non-blistering of the films is a result of the low intrinsic stress (compressive) in the films and not due to a low H content, which, in fact, is much higher in the non-blistering films than in the C-, N-, and O-free films. Among the three types of non-blistering Si-rich amorphous films, we conclude that the O-incorporated one is the most suitable for application in SiOx-based passivating contacts owing to the film’s high excess Si content and ability to crystallize.

Green Synthesis of Lead Sulphide Nanoparticles for High-Efficiency Perovskite Solar Cell Applications.

In this study, lead sulfide (PbS) nanoparticles were synthesized by the chemical precipitation method using Aloe Vera extract with PbCl2 and Thiourea (H2N-CS-NH2). The synthesized nanoparticles have been investigated using x-ray diffraction (XRD), UV-Vis, energy-dispersive x-ray spectroscopy (EDX), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). XRD and TEM results confirm that the films are in the cubic phase. The crystallite size, lattice constant, micro-strain, dislocation density, optical bandgap, etc. have been determined using XRD and UV-Vis for investigating the quality of prepared nanoparticles. The possible application of these synthesized nanoparticles in the solar cells was investigated by fabricating the thin films on an FTO-coated and bare glass substrate. The properties of nanoparticles were found to be nearly retained in the film state as well. The experimentally found properties of thin films have been implemented for perovskite solar cell simulation and current-voltage and capacitance-voltage characteristics have been investigated. The simulation results showed that PbS nanoparticles could be a potential hole transport layer for high-efficiency perovskite solar cell applications.

Accelerated Formation of 2D Ruddlesden-Popper Perovskite Thin Films by Lewis Bases for High Efficiency Solar Cell Applications.

Various types of 2D organic–inorganic perovskite solar cells have been developed and investigated due to better electron transport behavior and environmental stability. Controlling the formation of phases in the 2D perovskite films has been considered to play an important role in influencing the stability of perovskite materials and their performance in optoelectronic applications. In this work, Lewis base urea was used as an effective additive for the formation of 2D Ruddlesden—Popper (RP) perovskite (BA)2(MA)n−1PbnI3n+1 thin film with mixed phases (n = 2~4). The detailed structural morphology of the 2D perovskite thin film was investigated by in situ X-ray diffraction (XRD), grazing-incidence small-angle X-ray scattering (GISAXS) and photoluminescence mapping. The results indicated that the urea additive could facilitate the formation of 2D RP perovskite thin film with larger grain size and high crystallinity. The 2D RP perovskite thin films for solar cells exhibited a power conversion efficiency (PCE) of 7.9% under AM 1.5G illumination at 100 mW/cm2.

Integrating Silicon In Armchair Graphene Nanoribbon For Solar Cell Applications

Solar power is not only free but also infinite and use of solar energy indeed has many advantages. Thus, solar technologies are greatly studied for producing low cost and better versions of existing devices that can be integrated in the existing photovoltaic (PV) systems. Many such devices like the solar powered curtains and clothes, cases for laptop and other electronic products are being produced. Silicon today is of course being used rapidly as a PV material for solar cell. However, a continuous effort has been made to use graphene for high efficiency solar cell applications and its use. Graphene on the other hand, is not very good at collecting the electrical current produced inside the solar cell but researchers are looking appropriately on this material. Many ways to modify graphene for this purpose are being studied. Solar cell requires semiconductor materials for exhibiting photovoltaic effect. As graphene is zero band gap material, hence, armchair graphene nanoribbons (AGNR) that are semiconducting are being looked up for solar cell applications. Therefore, in this present work, various attempts have been made to investigate the electronic bandgap by using AGNRs in solar cells. The in-depth analysis of electronic properties has been done where band structure, density of states and geometrical stability on the basis of transmission of energy has been examined. Further, AGNR doping with silicon has been performed in which we have replaced the carbon with silicon. Initially, we started with one-silicon atom as a dopant and then went upto 4 silicon as dopant and the variations has been compared. Thus, through this analysis, the use of doped AGNRs in solar cells is investigated.

Omnidirectional and Broadband Antireflection Effect with Tapered Silicon Nanostructures Fabricated with Low-Cost and Large-Area Capable Nanosphere Lithography.

In this report, we present a process for the fabrication and tapering of a silicon (Si) nanopillar (NP) array on a large Si surface area wafer (2-inch diameter) to provide enhanced light harvesting for Si solar cell application. From our N,N-dimethyl-formamide (DMF) solvent-controlled spin-coating method, silica nanosphere (SNS in 310 nm diameter) coating on the Si surface was demonstrated successfully with improved monolayer coverage (>95%) and uniformity. After combining this method with a reactive ion etching (RIE) technique, a high-density Si NP array was produced, and we revealed that controlled tapering of Si NPs could be achieved after introducing a two-step RIE process using (1) CHF3/Ar gases for SNS selective etching over Si and (2) Cl2 gas for Si vertical etching. From our experimental and computational study, we show that an effectively tapered Si NP (i.e., an Si nanotip (NT)) structure could offer a highly effective omnidirectional and broadband antireflection effect for high-efficiency Si solar cell application.

Properties of sputtered BaSi2 thin films annealed in vacuum condition

As a potential absorber candidate for high-efficient solar cell applications, BaSi2 films are confronted with issues of surface oxidation associated with the high-temperature annealing. Herein, BaSi2 films are deposited by the sputtering technique. A vacuum annealing process is subsequently carried out to crystallize sputtered BaSi2 films. Raman spectroscopy is used to study surface structures and crystalline quality. Elemental depth profile is measured by Auger Electron spectroscopy to understand the compositions of films. Optical and electrical properties are further investigated to reveal the effects of annealing condition. Applying vacuum annealing condition can effectively suppress diffusions of Ba and ensures a stochiometric BaSi2 layer. However, surface oxidation still occurs even in the vacuum environment owing to the high reactivity of Ba. Further attempts to prevent BaSi2 surface oxidation may focus on the combination of other methods, such as capping layer and reducing atmosphere, with vacuum (or low-pressure) annealing condition.

High optoelectronic performance of ZnO films co-doped with ternary functional elements of F, Al and Mg

For use as front electrodes in high-efficiency thin-film solar cells, ZnO transparent conductive films must have both broad spectral transmission and high conductivity. However, these characteristics are difficult to achieve simultaneously. In this work, F, Al, and Mg co-doped ZnO (FAMZO) films with superior electrical and optical properties were fabricated by RF magnetron sputtering and rapid thermal annealing (RTA). F and Al co-doping enables the film to maintain low resistivity and high transmittance in the visible and near-infrared regions, while Mg doping widens the optical band gap. Morphological characterization shows that the FAMZO films undergo recrystallization and growth during RTA, which further improves their electrical and optical properties. Our FAMZO films achieved a resistivity of 4.07 × 10−4 Ω cm, a mobility of 47.85 cm2/V, a carrier concentration of 3.21 × 1020 cm−3, and 90.54% average transmittance between 400 and 1400 nm. The excellent performance of our ZnO films makes them suitable for a broad range of applications in high-efficiency thin-film solar cells.

Interfacial Engineering through Chloride-Functionalized Self-Assembled Monolayers for High-Performance Perovskite Solar Cells.

The family of organic-inorganic hybrid perovskite (OIHPs) materials is one of the most promising for very high-efficiency photovoltaic solar cell application. In the present work, the effect of a series of self-assembled monolayers placed at the TiO2-perovskite junction, on the functioning of triple cation perovskite solar cells has been investigated. We show that employing 4-chlorobenzoic acid leads to the marked boosting of the solar cell performances. The starting pristine cell had a power conversion efficiency (PCE) of 20.3% and the chemical engineering permitted to reach a PCE up to 21.35%. Our experimental study completed by density functional theory calculations and modeling show that this progress is due to the reduction of interfacial states, to the improvement of the quality of the OIHP material and to the structural continuity between TiO2 and the OIHP. Especially, we demonstrate that the interfacial chemical interactions are important to consider in the design of highly efficient devices.

Acceleration of the Decay of Excitons in an Organometallic Perovskite Film on the Crystalline Silicon Surface

It has been found that the optical properties and characteristics of exciton photoluminescence in thin organometallic perovskite layers, which are promising for application in high-efficiency solar cells, change when these layers are deposited on a crystalline silicon (c-Si) substrate. The observed shift of the photoluminescence band toward higher photon energies and a decrease in the lifetime of photoluminescence compared to layers deposited on a glass substrate with conducting metal oxide coating have been explained by the effect of an electric field that is formed in an organometallic perovskite/c-Si heterostructure and leads to the field ionization and the decay of excitons in the organometallic perovskite layer.

Optical properties of a random inverted pyramid textured silicon surface studied by the ray tracing method

The random inverted pyramid texture has been extensively studied experimentally in high-efficiency monocrystalline silicon solar cells due to its superior optical properties. In this paper, a random inverted pyramid structure model was established, and the optical performance was studied by the ray tracing method. It has five common light paths and can achieve lower reflectance than random upright pyramids. To further analyze the optical properties of random inverted pyramids, a simplified random inverted pyramid model, which consists of two overlapping inverted pyramids, was studied and analyzed in detail. The proportions of the light path related to different overlapping regions, and the reflectance ranging from 10.11% to 10.64%, can be obtained, which is lower than the reflectivity of random upright pyramids. We believe that the random inverted pyramid texture can have a wide range of applications in high-efficiency monocrystalline silicon solar cells.

Numerical simulation of graphene/GaAs heterojunction solar cells

For a thorough understanding of graphene/GaAs heterojunction solar cells, the effect of the graphene work function, absorption loss, density of interface states, as well as the incorporation of an AlxGa1−xAs (0≤x≤1) buffer layer on the performance of graphene/GaAs heterojunction solar cells was investigated via AFORS-HET simulation software. It is demonstrated that graphene with a work function of approximately 5 eV favors the efficiency improvement. The absorption loss is also an unnegligible factor for the optimization of the graphene work function. The density of interface states can significantly affect the carrier recombination at the heterojunction interface between graphene and GaAs and the corresponding photovoltaic performance. In addition, the work function of a back electrode should also be taken into account for selecting a back electrode material due to its significant influence on the carrier transportation and collection. Furthermore, when an AlxGa1−xAs (x = 0.2) buffer layer was introduced to this heterojunction interface, an enhanced photovoltaic conversion efficiency of 24.78% can be achieved. Finally, a comparison among simulation and experimental data for the graphene/GaAs heterojunction solar cells is presented. This study indicates the great potential of graphene/GaAs heterojunction for the application in high-efficiency solar cells.