Antireflection Layer Research Articles

Unraveling Optical and Electrical Gains of Perovskite Solar Cells with an Antireflective and Energetic Cascade Electron Transport Layer

Electron transport layers (ETLs) are imperative in n-i-p structured perovskite solar cells (PSCs) because of their capability to affect light propagation, electron extraction, and perovskite crystallization, and any mismatch of optical constants, band position, and surface potential between the ETLs and the perovskites can cause unintentional optical and electrical losses. Herein, an antireflective and energetic cascade bilayer ETL with ubiquitously used SnO2 and TiO2 was constructed at 150 °C for PSCs, and the in-depth mechanism for performance improvement was systematically unraveled. It was revealed that the construction of an ETL with gradually increasing refractive indices can circumvent light reflection loss, resulting in enhanced photocurrent. The combined ETL forms an energetic cascade to promote electronic conductivity and facilitate electron extraction with reduced energy loss. Moreover, topologic perovskite growth with improved crystallinity and vertical orientation was preferred owing to the relative dewetting behavior, leading to reduced defect states and enhanced carrier mobility in the perovskite layer.

All‐Glass Metasurfaces for Ultra‐Broadband and Large Acceptance Angle Antireflectivity: from Ultraviolet to Mid‐Infrared

AbstractFor many optics technologies, such as display screens, solar cells, laser systems, and eyeglasses, antireflective (AR) coatings are well integrated; these applications frequently benefit from the ability to function as broadband AR. Here, all‐glass metasurfaces are reported on, exhibiting a measured reflectance of 0.18% ± 0.23% per interface, averaged across wavelengths spanning from 350 nm (ultraviolet) to 2350 nm (mid‐infrared); to the best of knowledge, this is the first‐ever demonstration of an AR layer capable of this. Furthermore, acceptance angles up to 100° (angle of incidence = ±50°) results in %R < 0.6% per interface over the band 350–1300 nm for P‐polarization and S‐polarization, with wavelength averaged reflectance values 0.04% ± 0.05% and 0.11% ± 0.15%, respectively – another technological first. The process advancements presented here allow for reflectance suppression over a broad range of wavelengths, angles, and polarizations.

Numerical prediction and optimization of the performance of CCTS-based thin film solar cell

Despite its direct band gap of about 1.5 eV, fabricated CCTS-based solar cells suffer from low efficiency. This paper presents a numerical simulation, using SCAPS software, for improving the efficiency of these solar cells. We optimized the work function of the back contact, the choice of the buffer layer, its thickness, its doping density, and finally, the absorber layer thickness. To minimize the reflection on the surface, we coted the solar cell with an anti-reflection layer of AlF3. We found that the optimal structure is: Ni/CCTS/ SnS2/ ZnMgO:Al/ AlF3 whose efficiency is 14.8 %. To avoid the problem of the expensive price of Ni, we proposed to use Mo as back contact and insert a p + -CCTS back surface field. With this solution, the output parameters are very close to that of the optimal structure.

Carrier Transport Properties in Few-Layer WS0.3Se1.7/(WOx)WS0.3Se1.7 Lateral p+–n Junctions Using a Metal–Oxide–Semiconductor Field-Effect Transistor (MOSFET) Structure

The carrier transport properties of lateral p+–n junctions composed of few-layer WS0.3Se1.7/(WOx)WS0.3Se1.7 on thermally grown SiO2 or high-κ amorphous Al0.74Ti0.26Oy dielectric layers on p+-Si substrates were investigated and analyzed using field-effect transistor structures. Plasma-laser irradiation promoted selective oxidation near the few-layer WS0.3Se1.7 surface and improved the rectification behavior of the current–voltage characteristics. A photocurrent current density (Jph) of 4 × 10–7 A/cm2 was recorded for WS0.3Se1.7/(WOx)WS0.3Se1.7 lateral p+–n junctions under simulated solar-light (AM1.5G) irradiation. Subsequently, improved Jph values of 7.1 × 10–6 (∼17 times) and 1.23 × 10–5 A/cm2 (∼30 times) were obtained by inserting a silver (Ag) back-reflector layer between the amorphous Al0.74Ti0.26Oy dielectric layer and p+-Si and an adding an antireflection (AR) layer of SnO2, respectively. In addition, an enhanced Jph of 1.3 × 10–5 A/cm2 was achieved with a Voc of 0.84 V and an FF of 57% upon applying a gate bias of +12 V. Thus, the photonic and electronic design of lateral p+–n junctions composed of few-layer WS0.3Se1.7/(WOx)WS0.3Se1.7 structures contributes to further research on various types of 2D lateral heterostructures for the application in optoelectronic and photovoltaic devices.

Interfacial Chemical Bridging Constructed by Multifunctional Lewis Acid for Carbon Nanotube/Silicon Heterojunction Solar Cells with an Efficiency Approaching 17.7.

Single-wall carbon nanotube/silicon (SWCNT/Si) heterojunction shows appealing potential for use in photovoltaic devices. However, the relatively low conductivity of SWCNT network and interfacial recombination of carriers have limited their photovoltaic performance. Herein, a multifunctional Lewis acid (p-toluenesulfonic acid, TsOH) is used to significantly reduce the energy loss in SWCNT/Si solar cells. Owing to the charge transfer doping effect of TsOH, the conductivity and work function of SWCNT films are optimized and tuned. More importantly, a chemical bridge is constructed at the interface of SWCNT/Si heterojunction. Experimental studies indicate that the phenyl group of TsOH can interact with SWCNTs through π-π interaction, meanwhile, the oxygen in the sulfonic functional group of the TsOH molecule can graft on the dangling bonds of the Si surface. The chemical bridge structure effectively suppresses the recombination of photogenerated carriers. The TsOH coating also works as an antireflection layer, leading to a 19% increment of the photocurrent. As a result, a champion power conversion efficiency of 17.7% is achieved for the TsOH-SWCNT/Si device, and it also exhibits an excellent stability, retaining more than 96% of the initial efficiency in the ambient air after 1 month.

Simulations of Antireflecting Coating on a Monocrystalline Silicon Solar Cell: Influence of Optical Parameters on a Double Layers

The decrease in the reflection of light on the lens is due to the porosity of the surface on a very thin thickness due to the refractive index became lower at 30 %. It is well known that the deposition of one or more layers of certain materials on the front face of the photovoltaic cells and optoelectronic devices such as lasers, diodes, reduces the reflection of the incident light, which improves the performance of the cells. Solar energy, whose efficiency varies around 60 %. In this study, the influence of the thickness of an antireflection layer, in this case SiO2, TiO2, MgF2, Si3N4, ZrO2 on the spectral response of the solar cell to silicon which passes up to about 90 % for a layer of MgF2/TiO2/Si whose refractive index values are respectively n = 1.3767 and n = 2.5742 quite far apart.

Materials Based on Amorphous Al2O3 and Composite W-Al2O3 for Solar Coatings Deposited by High-Rate Sputter Processes

In parabolic trough technology, the development of thermally and structurally stable solar coatings plays a key role in determining the efficiency, durability, and economic feasibility of tube receivers. A cermet-based solar coating is typically constituted by a thin film stratification, where a multilayer graded cermet is placed between an infrared metallic reflector and an antireflection filter. This work reports the realization of materials based on Al2O3 and W characterized by high structural and chemical stability in vacuum at high temperature, obtained through the optimization of high-deposition-rate processes. Al2O3 material, employed as the antireflection layer, was deposited through a reactive magnetron sputtering process at a high deposition rate. Cermet materials based on W-Al2O3 were deposited and employed as absorber layers by implementing reactive magnetron co-sputtering processes. An investigation into the stability of the realized samples was carried out by means of several material characterization methods before and after the annealing process in vacuum (1 × 10−3 Pa) at high temperature (620 °C). The structural properties of the samples were evaluated using Raman spectroscopy and XRD measurements, revealing a negligible presence of oxides that can compromise the structural stability. Spectrophotometric analysis showed little variations between the deposited and annealed samples, clearly indicating the high structural stability.

Anti-reflection Layer-Sputtered Transparent Polyimide Substrate with Reliable Adhesion Strength to the Copper Layer.

Parameters of DC-reactive magnetron sputtering are optimized to deposit anti-reflection (AR) layers on transparent polyimide (PI) substrates, followed by the deposition of the conductive copper layer, to fabricate practically reliable composite films as advanced flexible circuits. When the deposition thickness is controlled and the gas composition during sputtering is adjusted, the resultant AR layer-coated PI film exhibits low reflectance and reveals improved adhesion strength to the copper layer. The adhesion reliability tests confirm that the peel strength between the PI film and the deposited layers could be further improved after thermal processing due to the formation of a worm-like morphology for better mechanical interlocking with layers. The facile sputtering process successfully fabricates a reliable substrate material with low reflectance and sufficient adhesion strength to copper for application as flexible printed circuits.

Antireflection and photocatalytic single layer and double layer ZnO and ZnO–TiO2 thin films

Due to climate change and the need to use renewable energy resources, solar cell modification is being considered by scientists around the world. Photocatalytic and anti-reflective coatings on solar cells can affect the efficiency and stability of solar cells. In this study, single-layer zinc oxide thin films and double-layer ZnO–TiO2 thin films were investigated to study their photocatalytic and optical properties. In fact, the effect of porosity and the application of double-layer thin films on the optical and photocatalytic properties of coated glass were studied. Mesoporous thin films thinner than 100 nm were synthesized using a sol-gel process and the ZnO thin film with 2 × 10-2 M pore-forming agent (CTAB) in the coating solution had the highest transparency and ultraviolet absorption, and the ZnO thin film with 4 × 10-2 M pore-forming agent had the best antireflection performance. The double-layer thin film consisted of dense (interlayer) and mesoporous (top layer) ZnO layers had the best anti-reflection performance. It reduced the reflection of the glass substrate by 2.05%. Investigation of the effect of the coating thickness on optical properties showed that higher film thickness can lead to a shift of the visible wavelength with the highest transparency such that the increase of withdrawal speed from 1 mm/s to 5 mm/s resulted in an increase of this wavelength from 530 nm to 590 nm. The photocatalytic studies of the ZnO double-layer coatings showed that 120 min of ultraviolet irradiation could completely recover the transparency of the samples contaminated with fatty acid.

Device simulation of perovskite/silicon tandem solar cell with antireflective coating

Optical design, photon management, and energy conversion efficiency are investigated through numerical simulation of perovskite/silicon tandem solar cell using the single-diode model. A strong near-infrared reflectance of roughly 60% is present in the perovskite-based top cell. ZnO and Si3N4 anti-reflection coating layers are placed on the surface of the perovskite layer and silicon sub-cell of the tandem solar cell respectively for photon management and minimizing the near-infrared reflectance loss. ZnO will act as an electron transport layer as well as an anti-reflection coating layer. The ZnO layer will minimize the near-infrared reflectance loss by the top cell in the device structure and allow the maximum transmittance of near-infrared photon energy to the silicon sub-cell. Intermediate anti-reflection Si3N4 layer assists in the maximum localization of the transmitted near-infrared photon energy in the silicon sub-cell. The efficiency of over 32% is achieved by optimizing the parameters of different materials such as perovskite, silicon, and anti-reflection coating layer in the tandem solar cell. The innovative idea of using electron transport material ZnO as an anti-reflection coating layer in the perovskite-based top cell can minimize the reflection loss by nearly 20%. The combination of ZnO and Si3N4 anti-reflection coating layers improved the conversion efficiency of the tandem cell by 1%. This result paves the way to realize highly efficient tandem solar cells through photon management.

Sputtered anti-reflection layer on transparent polyimide - substrate improves adhesion strength to - copper layer: effects of layer thickness and sputtering power.

In order to shield the electronic circuits on a transparent polyimide (PI) substrate, an anti-reflection (AR) layer was deposited on a PI film via DC reactive magnetron sputtering. The effects of sputtering power and thickness of AR layer on the optical property and adhesion strength of the PI were investigated. The composition of the AR layer influences the bonding between layers. Sufficient thickness of the AR layer is essential to strengthen the adhesion between the PI and copper (Cu) layers. The sputtered AR layer on the PI also improves the barrier property for water vapor. The AR layer-sputtered PI substrates remain transparent and exhibit high peel strength to the Cu layer, suggesting their potential applications as reliable transparent substrates for modern electronic devices.

Rational and key strategies toward enhancing the performance of graphene/silicon solar cells

Several strategies are presented to enhance the performance of graphene-based solar cells. These strategies include chemical doping, incorporation of an interlayer, and controlling the reflectivity with an antireflection layer.

Investigation into the Characteristics of Double-Layer Transparent Conductive Oxide ITO/TNO Anti-Reflection Coating for Silicon Solar Cells

In this study, indium–tin oxide (ITO)/Nb-doping TiO2 (TNO) double-layer transparent conductive oxide (TCO) films deposited using DC magnetron sputtering were used as a surface anti-reflection layer with an overall thickness of 100 nm for double-layer films. The simulated results showed that ITO and TNO thickness combinations of 90 nm/10 nm, 80 nm/20 nm, and 70 nm/30 nm had a higher transmittance and lower reflectance than others in the visible wavelength range. Compared to the single-layer ITO films, for ITO/TNO films deposited on the glass and silicon substrates with an optimum thickness of 80/20 nm, the reflectance was reduced by 5.06% and 4.63%, respectively, at the central wavelength of 550 nm and crystalline silicon photo response wavelength of 900 nm. Moreover, the near-infrared reflectance of the double-layer ITO/TNO with thickness combinations of 90 nm/10 nm, 80 nm/20 nm, and 70 nm/30 nm, when deposited on silicon substrates, was obviously improved by the graded refractive index lamination effect of air (1)/ITO (1.98)/TNO (2.41)/Si (3.9).

Additively-Manufactured All-Dielectric Microwave Polarization Converters Using Ceramic Stereolithography

We report a class of all-dielectric, additively-manufactured polarization converters with tailored temporal frequency responses within the Ku and Ka microwave bands (15 – 40 GHz). These multi-layer devices consist of cascaded, subwavelength, high-contrast gratings with different fill fractions and orientations, providing control over the effective anisotropic properties of each layer. In design, the subwavelength gratings are modeled as homogeneous anisotropic layers. This allows the overall metastructure to be treated as a stratified dielectric medium. Therefore, it can be analyzed and optimized using plane-wave transfer matrix techniques that fully account for multiple reflections between layers. Using this cascaded grating geometry, a variety of high-efficiency microwave polarization converters can be realized with broadband, multiband, or multifunctional behavior. The transmissive metastructures do not require anti-reflection layers since impedance matching is incorporated into their design. Three example devices based on alumina/air gratings have been monolithically fabricated using ceramic stereolithography: a broadband reflective half-wave plate, a broadband isotropic polarization rotator, and a dual-band linear-to-circular polarization converter.

Multilevel transmission contrast in optical structures with thin films of GeTe

Analysis of the optical properties: refractive index n(λ) and extinction coefficient k(λ), of thin films of phase-change materials obtained by photometric and ellipsometric methods allows to optimize optical characteristics reflection R, transmission T and absorption A. The interference of an electromagnetic wave in an absorbing thin film on a dielectric substrate significantly affects the values of the optical characteristics. Optimization of the optical characteristics is possible through the use of additional layers of dielectric materials, which are used to compensate for the difference in the refractive indices of the film with the substrate and air and minimize the reflection. This approach will increase the contrast of the transmission levels for the modulated optical signal in near infrared range. Calculations of the optical characteristics of thin films of germanium telluride in multi-layer structures are performed. Experimental samples of structures with antireflection layers of zinc sulfide have been prepared and their optical transmission characteristics have been investigated. The combination of multilayer structures for the implementation of contrast levels of transmission have been determined.

Antireflective and Hard Multicoat Design for Allyl Diglycol Carbonate Plastic Spectacle Lenses

A design of coating with single, double, and three-layers for allyl diglycol carbonate (CR-39) spectacle lenses has been done. The coating included anti-reflection (AR) layers for back and front surfaces which allow the transmission to reach 99 % of incident light on the eye. This design shows spectacle lenses of higher contrast images, decreasing ghost images, and little driving glare at night as well as more cosmetic. The anti-reflection layers increased scratch resistance, and cleanability, and make lenses nearly invisible and durable Keywords: AR coating, thin-film coating, plastic glasses, hard multi-coating.

Colored Silicon Heterojunction Solar Cells Exceeding 23.5% Efficiency Enabled by Luminescent Down-Shift Quantum Dots.

Colored solar panels, realized by depositing various reflection layers or structures, are emerging as power sources for building with visual aesthetics. However, these panels suffer from reduced photocurrent generation due to the less efficient light harvesting from visible light reflection and degraded power conversion efficiency (PCE). Here, color-patterned silicon heterojunction solar cells are achieved by incorporating luminescent quantum dots (QDs) with high quantum yields as light converters to realize an asthenic appearance with high PCE. It is found that large bandgap (blue) QD layers can convert UV light into visible light, which can notably alleviate the parasitic absorption by the front indium tin oxide and doped amorphous silicon. Additionally, a universal optical path model is proposed to understand the light transmission process, which is suitable for luminescent down-shift devices. In this study, solar cells with a PCE exceeding 23.5% are achieved using the combination of a blue QD layer and a top low refractive index anti-reflection layer. Based on ourbest knoledge,the obtained PCE is the highest for a color-patterned solar cell. The results suggest an enhanced strategy involving incorporation of luminescent QDs with an optical path design for high-performance photovoltaic panels with visual aesthetics.

Insights in light trapping for new generation silicon solar cell: optical characterization of plasmonic nanostructures beside anti-reflection layer

Designing light-trapping is one of the requirements for new generation silicon solar cells. Herein, the optical properties of front-based plasmonic nanoparticles besides the anti-reflection layer on new-generation silicon cells were investigated by the 3D-FDTD method. The simulated results were compared with some experimental kinds of literature. In addition to a perfectly periodic structure, the nearly regular structure (closer to the experimental one) was also modeled. Along with the conventional far, near-field effect, generation rate, and ideal Jsc, enhancement in quantum efficiency (g-curve) and integrated quantum efficiency (G-value) were used as suitable characterizing sets. The g-curve result of the sample with the anti-reflection layer showed superiority compared to the standard cell in the ~ full wavelength range. Moreover, the thickness engineering of the anti-reflection layer can significantly increase cell performance (G = 1.4). In contrast, the plasmonic structure was not more effective according to the g-curve of some optimum plasmonic samples for wavelengths below 500 nm. The best G-value among plasmonic samples was 1.3. Also, using both anti-reflection with the plasmonic design did not significantly improve the optical performance. The results determined that the plasmonic system can lead to a considerable decrease in spectral reflectance, consistent with some reported experimental ones. Moreover, the simulations clarified the cause of the lack of necessary plasmonic enhancement in some experimental studies could be attributed to the lateral trap of the light. In other words, this reduction in reflection does not lead to notable transit near and far-field into the active layer.

Atom-to-Device Simulation of MoO3/Si Heterojunction Solar Cell

Metal oxides are commonly used in optoelectronic devices due to their transparency and excellent electrical conductivity. Based on its physical properties, each metal oxide serves as the foundation for a unique device. In this study, we opt to determine and assess the physical properties of MoO3 metal oxide. Accordingly, the optical and electronic parameters of MoO3 are evaluated using DFT (Density Functional Theory), and PBE and HSE06 functionals were mainly used in the calculation. It was found that the band structure of MoO3 calculated using PBE and HSE06 exhibited indirect semiconductor properties with the same line quality. Its band gap was 3.027 eV in HSE06 and 2.12 eV in PBE. Electrons and holes had effective masses and mobilities of 0.06673, -0.10084, 3811.11 cm2V-1s-1 and 1630.39 cm2V-1s-1, respectively. In addition, the simulation determined the dependence of the real and imaginary components of the complex refractive index and permittivity of MoO3 on the wavelength of light, and a value of 58 corresponds to the relative permittivity. MoO3 has a refractive index of between 1.5 and 3 in the visible spectrum, which can therefore be used as an anti-reflection layer for solar cells made from silicon. In addition, based on the semiconducting properties of MoO3, it was estimated that it could serve as an emitter layer for a solar cell containing silicon. In this work, we calculated the photoelectric parameters of the MoO3/Si heterojunction solar cell using Sentaurus TCAD (Technology Computing Aided Design). According to the obtained results, the efficiency of the MoO3/Si solar cell with a MoO3 layer thickness of 100 nm and a Si layer thickness of 9 nm is 8.8%, which is 1.24% greater than the efficiency of a homojunction silicon-based solar cell of the same size. The greatest short-circuit current for a MoO3/Si heterojunction solar cell was observed at a MoO3 layer thickness of 60 nm, which was determined by studying the dependency of the heterojunction short-circuit current on the thickness of the MoO3 layer.

Recent Applications of Antireflection Coatings in Solar Cells

The antireflection coating (ARC) suppresses surface light loss and thus improves the power conversion efficiency (PCE) of solar cells, which is its essential function. This paper reviews the latest applications of antireflection optical thin films in different types of solar cells and summarizes the experimental data. Basic optical theories of designing antireflection coatings, commonly used antireflection materials, and their classic combinations are introduced. Since single and double antireflection coatings no longer meet the research needs in terms of antireflection effect and bandwidth, the current research mainly concentrates on multiple layer antireflection coatings, for example, adjusting the porosity or material components to achieve a better refractive index matching and the reflection effect. However, blindly stacking the antireflection films is unfeasible, and the stress superposition would allow the film layer to fail quickly. The gradient refractive index (GRIN) structure almost eliminates the interface, which significantly improves the adhesion and permeability efficiency. The high-low-high-low refractive index (HLHL) structure achieves considerable antireflection efficiency with fewer materials while selecting materials with opposite stress properties improves the ease of stress management. However, more sophisticated techniques are needed to prepare these two structures. Furthermore, using fewer materials to achieve a better antireflection effect and reduce the impact of stress on the coatings is a research hotspot worthy of attention.