Almost half of the solar energy that reaches a silicon solar cell is lost due to the reflection at the silicon–air interface.Antireflective coatings aim to suppress the reflection and thereby to increase the photogen...Almost half of the solar energy that reaches a silicon solar cell is lost due to the reflection at the silicon–air interface.Antireflective coatings aim to suppress the reflection and thereby to increase the photogenerated current.The conventional few-layer dielectric antireflective coatings may significantly boost the transmission of solar light,but only in a narrow wavelength range.Using forward and inverse design optimization algorithms,we develop the designs of antireflective coatings for silicon solar cells based on single-layer silicon metasurfaces(periodic subwavelength nanostructure arrays),leading to a broadband reflection suppression in the wavelength range from 500 to 1200 nm for the incidence angles up to 60 deg.The reflection averaged over the visible and near-infrared spectra is at the record-low level of approximately 2%and 4.4%for the normal and oblique incidence,respectively.The obtained results demonstrate the potential of machine learning–enhanced photonic nanostructures to outperform the classical antireflective coatings.展开更多
SiO_(2)/TiO_(2)composite films have been frequently used to realize the functions of self-cleaning and antireflection.Increasing the TiO_(2)volume ratio in SiO_(2)/TiO_(2)composite film is beneficial to enhance the se...SiO_(2)/TiO_(2)composite films have been frequently used to realize the functions of self-cleaning and antireflection.Increasing the TiO_(2)volume ratio in SiO_(2)/TiO_(2)composite film is beneficial to enhance the self-cleaning effect,while high TiO_(2)content leads to a strong Rayleigh scattering and depresses the antireflective performance,resulting in a bottleneck problem for the dual-functional application.Here,we have achieved a high-quality TiO_(2)nanotubes film with excellent antireflective and near-perfect selfcleaning performances.Ultrasound assisted pickling method has been developed to effectively prepare the well-dispersed protonated titanate nanotubes colloid.After spin-coating and annealing treatment,glass substrate coated with double-side TiO_(2)nanotubes film has a peak transmittance of 99.2%and average transmittance of 97.4%at 400-800 nm.Ultra-high porosity of TiO_(2)nanotubes film(80%)and ultra-fine size of TiO_(2)nanotubes(8.6 nm in outer diameter)lead to excellent antireflective performance.With high UV absorptivity(80%at 254 nm)and formal quantum efficiency of stearic acid(10.9×10^(-3)),TiO_(2)nanotubes film shows near-perfect self-cleaning performance.A persistent anti-fogging ability is also presented.This study demonstrates the feasibility to fabricate pure TiO_(2)antireflective coating for glass substrate,extends application field of the classic TiO_(2)nanotubes,and sheds lights on the practical applications of high-powered TiO_(2)nanotube-based multi-functional films.展开更多
We reported a facile and bio-inspired strategy for obtaining antireflective （AR） coating through polymerization-induced self-wrinkling. Upon irradiation of light, the complex wrinkle micro-patterns with different mo...We reported a facile and bio-inspired strategy for obtaining antireflective （AR） coating through polymerization-induced self-wrinkling. Upon irradiation of light, the complex wrinkle micro-patterns with different morphologies were generated spontaneously on the surface of coating during photo-cross- linking, which enables the photo-curing coating can decrease reflection. The resulting photo-curing coating exhibits a high transmittance over 90% and low reflection below 5% ～ 8%, with an efficiency anti- reflection of 4% ～ 7%; compared to the flat blank coating. The successful application of these AR coatings with wrinkles pattern to encapsulate the thin film solar cells results in appreciable photovoltaic performance improvement of more than 4% ～ 8%, which benefits from the decrease of the light reflection and increase of optical paths in the photoactive layer by the introduction of wrinkling pattern. Furthermore, the efficiency improvements of the solar cells are more obvious, with a remarkable increase of 8.5%, at oblique light incident angle than that with vertical light incident angle展开更多
Conventional porous MgF2 antireflective films show poor environmental durability due to its hydrophilic nature.To improve the film environmental durability,hydrophobic porous MgF2 antireflective films are prepared by ...Conventional porous MgF2 antireflective films show poor environmental durability due to its hydrophilic nature.To improve the film environmental durability,hydrophobic porous MgF2 antireflective films are prepared by a methyl silicone-modified MgF2 sol.Effects of the methyl silicone proportions on the film properties are examined in order to control the wettability,peak transmittance,and environmental durability of the films.The modification of methyl silicone can increase the film hydrophobicity,thus decreases the adsorption of water,and improves the environmental durability.However,large amounts of methyl silicone could increase the film refractive index,resulting in the decrease in peak transmittance for films on BK7 glass.Films with 40% silicone show water contact angle of 110°,peak transmittance of 98.7%,and good environmental durability.The results of accelerated test show that the environmental durability of the porous MgF2 films modified with 40% methyl silicone is six times higher than that of the conventional films.展开更多
Depositing an antireflection coating on the front surface of solar cells allows a significant reduction in reflection losses. It thus allows an increase in the efficiency of the cells. A modeling of the refractive ind...Depositing an antireflection coating on the front surface of solar cells allows a significant reduction in reflection losses. It thus allows an increase in the efficiency of the cells. A modeling of the refractive indices and the thicknesses of an optimal antireflection coating has been proposed. Thus, the average reflective losses can be reduced to less than 8% and less than 2.4% in a large wavelength range respectively for a single-layer and double-layer anti-reflective coating types. However, the difficulty of finding these model materials (materials with the same refractive index) led us to introduce two notions: the refractive index difference and the thickness difference. These two notions allowed us to compare the reflectivity of the antireflection layer in silicon surface. Thus, the lower the refractive index difference is, the more the material resembles to the ideal material (in refractive index), and thus its reflective losses are minimal. SiNx and SiO2/TiO2 antireflection layers, in the wavelength range between 400 and 1100 nm, have reduced the average reflectivity losses to less than 9% and 2.3% respectively.展开更多
Antireflection layers are commonly used in photovoltaics to increase light absorption and therefore increase maximum photocurrent.Here,pyramid structures are created on Si surfaces with alkaline solution etching.The e...Antireflection layers are commonly used in photovoltaics to increase light absorption and therefore increase maximum photocurrent.Here,pyramid structures are created on Si surfaces with alkaline solution etching.The extent of pyramid coverage depends directly on the reaction time and as a result,the surface reflectance decreases with reaction time.展开更多
We present a facile method for producing superhydrophobic nanograss-coated （SNGC） glass surfaces that possess both reduced reflectivity and self-cleaning properties at the air/glass interface. The refractive index o...We present a facile method for producing superhydrophobic nanograss-coated （SNGC） glass surfaces that possess both reduced reflectivity and self-cleaning properties at the air/glass interface. The refractive index of a CaF2 nanograss （NG） layer on a glass substrate, deposited by glancing angle vapor deposition, is 1.04 at 500 nm, which is the second-lowest value ever reported so far. The fluorinated NG layer gives rise to a high water contact angle （〉150°） and very efficient cleaning out of dust with water drops. Using the dual functionalities of the SNGC glass, we demonstrate superhydrophobic and antireflective organic photovoltaic cells with excellent power conversion efficiency.展开更多
A type of λ/4–λ/4 ultra-broadband antireflective coating has been developed using modified low refractive silica and high refractive silica layers by a sol–gel dip coating method for amplifier blast shields of the...A type of λ/4–λ/4 ultra-broadband antireflective coating has been developed using modified low refractive silica and high refractive silica layers by a sol–gel dip coating method for amplifier blast shields of the Shen Guang Ⅱ high power laser facility(SG-Ⅱ facility). Deposition of the first layer(high refractive index silica) involves baking at 200℃ in the post-treatment step. The second layer(low refractive index, n = 1.20) uses low refractive index silica sol modified by acid catalysis. Thermal baking at temperatures no less than 500℃ for 60 min offers chemical stability, ethanol scratch resistance, and resistance to washing with water. The average residual reflection of dual-side-coated fused silica glass was less than 1% in the spectral range from 450 to 950 nm. Transmission gain has been evaluated by taking into account angular light, and the results show that the transmission gain increases with increasing light incidence. Even at 60°, the transmission spectrum of the broadband antireflective coating effectively covered the main absorption peak of Nd:glass.展开更多
Using methyl triethoxysilicane as precursor, a moisture-resistant coating for neodymium-doped laser glass was developed by the sol-gel process. Colloidal silica was added in coating solution as modifier. The refractiv...Using methyl triethoxysilicane as precursor, a moisture-resistant coating for neodymium-doped laser glass was developed by the sol-gel process. Colloidal silica was added in coating solution as modifier. The refractive index of this coating varied from 1.31 to 1.42. A porous antireflective （AR） silica coating with the index of 1.27 was coated on the moisture-resistant coating surface. The two-layer coating possessed transmission up to 99.1% at wavelength of 966 nm, surface root-mean-square （RMS） roughaess of 1.245 am, and roughness of average （RA） of 0.961 am. In the case of laser of 1053-nm laser waveleilgth and 1-ns pulse duration, the damage threshold of the two-layer coatings was more than 15 J/cm^2.展开更多
A new silica antireflective coating with improved hydrophobicity and optical stability in a vacuum is obtained by a two-step route. Firstly, silica sols are prepared with a sol-gel process, in which tetraethyl orthosi...A new silica antireflective coating with improved hydrophobicity and optical stability in a vacuum is obtained by a two-step route. Firstly, silica sols are prepared with a sol-gel process, in which tetraethyl orthosilicate is utilized as a precursor. And by introduction of fluorine containing glycol into the sols, the porosity of silica particles and surface polarity of the coatings are decreased. Afterward, coatings are constructed with low surface roughness by modification of PMBA-PMMA. The coatings retain transmission of up to 99.6%, and laser damage threshold of about 50 J/cm^2 at a wavelenth of 532 nm （1-on-1. 10 ns）展开更多
A λ∕4–λ∕4 broadband antireflective(AR) coating is developed with a sol-gel dip-coating method. By adding SAR-5 organosilicon resin into a base-catalyzed silica sol top layer and treating at 300°C, a broadban...A λ∕4–λ∕4 broadband antireflective(AR) coating is developed with a sol-gel dip-coating method. By adding SAR-5 organosilicon resin into a base-catalyzed silica sol top layer and treating at 300°C, a broadband AR coating used for blast shields with a high average transmission of 99.34%(450–950 nm) and good hydrophobicity(with a water-contact angle of 119°) was obtained. After being subjected to rubbing 50 times and being maintained at a relative humidity of around 95% for 50 days, the average transmission of the coating decreased by0.29% and 0.04%, respectively. This indicates that the organically modified silica(ORMOSIL) broadband AR coating has good abrasion resistance and humidity stability.展开更多
Although perovskite solar cells(PSCs)have achieved encouraging efficiency,the photon loss at the substrate due to light reflection has not been well addressed.Light management is promising to reduce reflection loss an...Although perovskite solar cells(PSCs)have achieved encouraging efficiency,the photon loss at the substrate due to light reflection has not been well addressed.Light management is promising to reduce reflection loss and realize higher power conversion efficiency(PCE)of PSCs.Here,a bilayer antireflective coating(ARC)has been designed and coated onto the backside of the glass substrate of(FAPbI_(3))_(x)(MAPbBr_(3))_(1-x)PSCs to enhance photon harvesting and consequently the device efficiency.The bottom layer of the bilayer ARC is made from a silica polymer and the top layer is made from the mixture of hexamethyldisiloxane-modified mesoporous silica nanoparticles and a fluorinated silica polymer.By adjusting the refractive index and the film thickness of each layer according to a two-layer model,enhanced glass transmittance in a broadband wavelength range can be reached,with the maximum transmittance increasing from ca.90%to over 95%.With the bilayer ARC,the maximum short-circuit current density and PCE of(FAPbI_(3))_(x)(MAPbBr_(3))_(1-x)PSCs can be increased from 25.5 m A cm^(-2)and 22.7%to 26.5 mA cm^(-2)and 23.9%with negligible changes in fill factor and opencircuit voltage.This work presents a simple yet effective strategy to enhance the efficiency of solar cells employing bilayer antirefective coatings,which can be applied to other types of solar cells.展开更多
Boron nitride(BN) nanosheets incorporated silica antireflective(AR) coating was successfully prepared on fused silica substrate to improve the antilaser-damage ability of transmissive optics used in high-power laser s...Boron nitride(BN) nanosheets incorporated silica antireflective(AR) coating was successfully prepared on fused silica substrate to improve the antilaser-damage ability of transmissive optics used in high-power laser systems. The BN nanosheets were obtained by urea assisted solid exfoliation, and then incorporated into basic-catalyzed silica sols without any further treatment. The transmission electron microscope(TEM) images indicated that the BN nanosheets generally consisted of 2–10 layers. The antireflective BN/SiO_2 coating exhibited excellent transmittance as high as 99.89% at351 nm wavelength on fused silica substrate. The thermal conductivity 0.135 W · m^(-1)· K^(-1) of the BN/SiO_2 coating with 10% BN addition was about 23% higher than 0.11 W · m^(-1)· K^(-1) of the pure SiO_2 AR coating. The laser-induced damage threshold(LIDT) of that BN/SiO_2 coating is also 23.1% higher than that of pure SiO_2 AR coating. This research provides a potential application of BN/SiO_2 coatings in high-power laser systems.展开更多
A facile approach was developed to fabricate visible/near-infrared antireflective(AR),superhydrophilic and anti-fogging thin films on glass substrates.Glass substrate was first etched by H_(2)SiF_(6)-based vapor and t...A facile approach was developed to fabricate visible/near-infrared antireflective(AR),superhydrophilic and anti-fogging thin films on glass substrates.Glass substrate was first etched by H_(2)SiF_(6)-based vapor and then dip-coated sequentially in a base-catalyzed 20 nm SiO_(2)nanoparticles sol and an acid-catalyzed SiO_(2)sol.After an-nealing,the prepared thin film(named E/BSiO_(2)/ASiO_(2))not only showed good optical and wetting properties,but also exhibited excellent mechanical properties.The thin film has enhanced transmittance in the spectral range of UV to near-infrared.The maximum transmittance of E/BSiO_(2)/ASiO_(2)thin film coated glass substrate is 98.4%in 400-1200 nm and 96.1%in 1200-2500 nm,respectively.Comparing with blank glass substrate,the average transmittance increases by 5%in the wavelength range of 300-2500 nm.Meanwhile,the film showed good anti-fogging performance.SEM and AFM were employed to characterize the morphology of the thin film.The pre-pared thin film has potential application in various areas,like solar cells,windowpanes and eyeglasses,and may also find applications in membrane-based separation,selective catalysis and sensors.展开更多
Antireflection surfaces and coatings have attracted considerable interests because they can maximize light transmittance of the substrates. In this work, zeolite antireflective （ZAR） coatings are prepared via layer-...Antireflection surfaces and coatings have attracted considerable interests because they can maximize light transmittance of the substrates. In this work, zeolite antireflective （ZAR） coatings are prepared via layer-by-layer （LBL） assembly of MFI-type zeolite silicalite-1 and polyelectrolyte. A micro- and macroporous hierarchical structure was obtained which contributes to the antireflective property of the zeolite coatings. The light transmittance of the coating on quartz can achieve as high as 99.3% at 650 nm. Furthermore, a superh~/drophobic ZAR coating can be obtained by chemical modification with 1H,1H,2H,2H-perfluorooctyl-triethoxysilane. This work demonstrates that zeolites are excellent candidates as high transparent superhydrophobic coatings.展开更多
Different post-treatment processes involving the use of ammonia and hexamethyldisilazane(HMDS) were explored for application to 351 nm third harmonic generation SiO_(2)antireflective(3ω SiO_(2)AR) coatings for high p...Different post-treatment processes involving the use of ammonia and hexamethyldisilazane(HMDS) were explored for application to 351 nm third harmonic generation SiO_(2)antireflective(3ω SiO_(2)AR) coatings for high power laser systems prepared by the sol-gel method.According to experimental analysis,the 3ω SiO_(2)AR coatings that were successively post-treated with ammonia and HMDS at 150℃ for 48 h and again heat-treated at 180℃ for 2 h(N/H 150+180 AR) were relatively better.There were relatively fewer changes in the optical properties of the N/H 150+180 AR coating under a humid and polluted environment,and the increase in defect density was slow in high humidity environments.The laser-induced damage threshold of the N/H 150+180 AR coating reached 15.83 J/cm;(355 nm,6.8 ns),a value that meets the basic requirements of high power laser systems.展开更多
Porous SiO2 antireflective (AR) coatings are prepared from the colloidal silica solution modified with methyltriethoxysilane (MTES) based on the sol-gel route. The viscosity of modified silica suspensions changes but ...Porous SiO2 antireflective (AR) coatings are prepared from the colloidal silica solution modified with methyltriethoxysilane (MTES) based on the sol-gel route. The viscosity of modified silica suspensions changes but their stability keeps when MTES is introduced. The refractive indices of modified coatings vary little after bake treatment from 100 to 150℃. The modified silica coatings on Ti:sapphire crystal, owning good homogeneity, display prominent antireflective effect within the laser output waveband (750-850 nm) of Ti:sapphire lasers, with average transmission above 98.6%, and own laser induced damage thresholds (LIDTs) of more than 2.2 J/cm2 at 800 nm with the pulse duration of 300 ps.展开更多
Mechanical strength is an essential parameter that influences and limits the lifetime performance of antireflective （AR） coatings in optical devices. Speciflcally, amphiphobic AR coatings with reduced reflectance ar...Mechanical strength is an essential parameter that influences and limits the lifetime performance of antireflective （AR） coatings in optical devices. Speciflcally, amphiphobic AR coatings with reduced reflectance are of great significance as they considerably enlarge the range of fundamental applications. Herein, we describe the design and fabrication of amphiphobic AR coatings with reduced reflectance and enhanced mechanical resilience. Introducing a thin polytetrafluoroethylene （PTFE） layer on top of the bilayer SiOz coating via vapor deposition method makes it highly liquid repellent. We achieved reduced reflectance （〈 1%） over the entire visible wavelength range, as well as tunability according to the desired wavelength region. The fabricated film showed better thermal stability （up to 300℃） with stable AR efficiency, when an ultrathin dense coat of Al2O3 was deposited via atomic layer deposition （ALD） on the polymer-based bilayer SiO2 antireflective coating （P-BSAR）. The experimental results prove that the omnidirectional AR coating in this study exhibits multifunctional properties and should be suitable for the production of protective optical equipment and biocompatible polymer films for the displays of portable electronic devices.展开更多
Coalbed methane(CBM)is a significant factor in triggering coal and gas outburst disaster,while also serving as a clean fuel.With the increasing depth of mining operations,coal seams that exhibit high levels of gas con...Coalbed methane(CBM)is a significant factor in triggering coal and gas outburst disaster,while also serving as a clean fuel.With the increasing depth of mining operations,coal seams that exhibit high levels of gas content and low permeability have become increasingly prevalent.While controllable shockwave(CSW)technology has proven effective in enhancing CBM in laboratory settings,there is a lack of reports on its field applications in soft and low-permeability coal seams.This study establishes the governing equations for stress waves induced by CSW.Laplace numerical inversion was employed to analyse the dynamic response of the coal seam during CSW antireflection.Additionally,quantitative calculations were performed for the crushed zone,fracture zone,and effective CSW influence range,which guided the selection of field test parameters.The results of the field test unveiled a substantial improvement in the gas permeability coefficient,the average rate of pure methane flowrate,and the mean gas flowrate within a 10 m radius of the antireflection borehole.These enhancements were notable,showing increases of 3 times,13.72 times,and 11.48 times,respectively.Furthermore,the field test performed on the CSW antireflection gas extraction hole cluster demonstrated a noticeable improvement in CBM extraction.After antireflection,the maximum peak gas concentration and maximum peak pure methane flow reached 71.2%and 2.59 m^(3)/min,respectively.These findings will offer valuable guidance for the application of CSW antireflection technology in soft and low-permeability coal seams.展开更多
基金support of the U.S.Civilian Research and Development Foundation“CRDF Global”(Grant No.G-202401-71609)。
文摘Almost half of the solar energy that reaches a silicon solar cell is lost due to the reflection at the silicon–air interface.Antireflective coatings aim to suppress the reflection and thereby to increase the photogenerated current.The conventional few-layer dielectric antireflective coatings may significantly boost the transmission of solar light,but only in a narrow wavelength range.Using forward and inverse design optimization algorithms,we develop the designs of antireflective coatings for silicon solar cells based on single-layer silicon metasurfaces(periodic subwavelength nanostructure arrays),leading to a broadband reflection suppression in the wavelength range from 500 to 1200 nm for the incidence angles up to 60 deg.The reflection averaged over the visible and near-infrared spectra is at the record-low level of approximately 2%and 4.4%for the normal and oblique incidence,respectively.The obtained results demonstrate the potential of machine learning–enhanced photonic nanostructures to outperform the classical antireflective coatings.
基金financially supported by the National Natural Science Foundation of China(No.12074356)the Major/Innovative Program of Development Foundation of Hefei Center for Physical Science and Technology(No.2018CXFX003)+1 种基金the Open Research Fund of State Key Laboratory of Pulsed Power Laser Technology(No.SKL2018KF07)Natural Science Foundation of Anhui Province(No.1808085ME131)。
文摘SiO_(2)/TiO_(2)composite films have been frequently used to realize the functions of self-cleaning and antireflection.Increasing the TiO_(2)volume ratio in SiO_(2)/TiO_(2)composite film is beneficial to enhance the self-cleaning effect,while high TiO_(2)content leads to a strong Rayleigh scattering and depresses the antireflective performance,resulting in a bottleneck problem for the dual-functional application.Here,we have achieved a high-quality TiO_(2)nanotubes film with excellent antireflective and near-perfect selfcleaning performances.Ultrasound assisted pickling method has been developed to effectively prepare the well-dispersed protonated titanate nanotubes colloid.After spin-coating and annealing treatment,glass substrate coated with double-side TiO_(2)nanotubes film has a peak transmittance of 99.2%and average transmittance of 97.4%at 400-800 nm.Ultra-high porosity of TiO_(2)nanotubes film(80%)and ultra-fine size of TiO_(2)nanotubes(8.6 nm in outer diameter)lead to excellent antireflective performance.With high UV absorptivity(80%at 254 nm)and formal quantum efficiency of stearic acid(10.9×10^(-3)),TiO_(2)nanotubes film shows near-perfect self-cleaning performance.A persistent anti-fogging ability is also presented.This study demonstrates the feasibility to fabricate pure TiO_(2)antireflective coating for glass substrate,extends application field of the classic TiO_(2)nanotubes,and sheds lights on the practical applications of high-powered TiO_(2)nanotube-based multi-functional films.
基金the National Natural Science Foundation of China (Nos. 21522403, 51373098)the National Basic Research Program (No. 2013CB834506)+1 种基金Education Commission of Shanghai Municipal Government (No. 15SG13)IFPM 2016B002 of Shanghai Jiao Tong University & Affiliated Sixth People’s Hospital South Campus for their financial support
文摘We reported a facile and bio-inspired strategy for obtaining antireflective （AR） coating through polymerization-induced self-wrinkling. Upon irradiation of light, the complex wrinkle micro-patterns with different morphologies were generated spontaneously on the surface of coating during photo-cross- linking, which enables the photo-curing coating can decrease reflection. The resulting photo-curing coating exhibits a high transmittance over 90% and low reflection below 5% ～ 8%, with an efficiency anti- reflection of 4% ～ 7%; compared to the flat blank coating. The successful application of these AR coatings with wrinkles pattern to encapsulate the thin film solar cells results in appreciable photovoltaic performance improvement of more than 4% ～ 8%, which benefits from the decrease of the light reflection and increase of optical paths in the photoactive layer by the introduction of wrinkling pattern. Furthermore, the efficiency improvements of the solar cells are more obvious, with a remarkable increase of 8.5%, at oblique light incident angle than that with vertical light incident angle
文摘Conventional porous MgF2 antireflective films show poor environmental durability due to its hydrophilic nature.To improve the film environmental durability,hydrophobic porous MgF2 antireflective films are prepared by a methyl silicone-modified MgF2 sol.Effects of the methyl silicone proportions on the film properties are examined in order to control the wettability,peak transmittance,and environmental durability of the films.The modification of methyl silicone can increase the film hydrophobicity,thus decreases the adsorption of water,and improves the environmental durability.However,large amounts of methyl silicone could increase the film refractive index,resulting in the decrease in peak transmittance for films on BK7 glass.Films with 40% silicone show water contact angle of 110°,peak transmittance of 98.7%,and good environmental durability.The results of accelerated test show that the environmental durability of the porous MgF2 films modified with 40% methyl silicone is six times higher than that of the conventional films.
文摘Depositing an antireflection coating on the front surface of solar cells allows a significant reduction in reflection losses. It thus allows an increase in the efficiency of the cells. A modeling of the refractive indices and the thicknesses of an optimal antireflection coating has been proposed. Thus, the average reflective losses can be reduced to less than 8% and less than 2.4% in a large wavelength range respectively for a single-layer and double-layer anti-reflective coating types. However, the difficulty of finding these model materials (materials with the same refractive index) led us to introduce two notions: the refractive index difference and the thickness difference. These two notions allowed us to compare the reflectivity of the antireflection layer in silicon surface. Thus, the lower the refractive index difference is, the more the material resembles to the ideal material (in refractive index), and thus its reflective losses are minimal. SiNx and SiO2/TiO2 antireflection layers, in the wavelength range between 400 and 1100 nm, have reduced the average reflectivity losses to less than 9% and 2.3% respectively.
基金The support of the Australian Research Council Discovery Program(DP150101354 and DP160101301)is gratefully acknowledged.
文摘Antireflection layers are commonly used in photovoltaics to increase light absorption and therefore increase maximum photocurrent.Here,pyramid structures are created on Si surfaces with alkaline solution etching.The extent of pyramid coverage depends directly on the reaction time and as a result,the surface reflectance decreases with reaction time.
文摘We present a facile method for producing superhydrophobic nanograss-coated （SNGC） glass surfaces that possess both reduced reflectivity and self-cleaning properties at the air/glass interface. The refractive index of a CaF2 nanograss （NG） layer on a glass substrate, deposited by glancing angle vapor deposition, is 1.04 at 500 nm, which is the second-lowest value ever reported so far. The fluorinated NG layer gives rise to a high water contact angle （〉150°） and very efficient cleaning out of dust with water drops. Using the dual functionalities of the SNGC glass, we demonstrate superhydrophobic and antireflective organic photovoltaic cells with excellent power conversion efficiency.
文摘A type of λ/4–λ/4 ultra-broadband antireflective coating has been developed using modified low refractive silica and high refractive silica layers by a sol–gel dip coating method for amplifier blast shields of the Shen Guang Ⅱ high power laser facility(SG-Ⅱ facility). Deposition of the first layer(high refractive index silica) involves baking at 200℃ in the post-treatment step. The second layer(low refractive index, n = 1.20) uses low refractive index silica sol modified by acid catalysis. Thermal baking at temperatures no less than 500℃ for 60 min offers chemical stability, ethanol scratch resistance, and resistance to washing with water. The average residual reflection of dual-side-coated fused silica glass was less than 1% in the spectral range from 450 to 950 nm. Transmission gain has been evaluated by taking into account angular light, and the results show that the transmission gain increases with increasing light incidence. Even at 60°, the transmission spectrum of the broadband antireflective coating effectively covered the main absorption peak of Nd:glass.
基金This work was supported by the National "863" Project of China (No. 863-804-2).
文摘Using methyl triethoxysilicane as precursor, a moisture-resistant coating for neodymium-doped laser glass was developed by the sol-gel process. Colloidal silica was added in coating solution as modifier. The refractive index of this coating varied from 1.31 to 1.42. A porous antireflective （AR） silica coating with the index of 1.27 was coated on the moisture-resistant coating surface. The two-layer coating possessed transmission up to 99.1% at wavelength of 966 nm, surface root-mean-square （RMS） roughaess of 1.245 am, and roughness of average （RA） of 0.961 am. In the case of laser of 1053-nm laser waveleilgth and 1-ns pulse duration, the damage threshold of the two-layer coatings was more than 15 J/cm^2.
基金supported by the National Major Project of Science and Technology under Grant No.2013ZX04006011-101
文摘A new silica antireflective coating with improved hydrophobicity and optical stability in a vacuum is obtained by a two-step route. Firstly, silica sols are prepared with a sol-gel process, in which tetraethyl orthosilicate is utilized as a precursor. And by introduction of fluorine containing glycol into the sols, the porosity of silica particles and surface polarity of the coatings are decreased. Afterward, coatings are constructed with low surface roughness by modification of PMBA-PMMA. The coatings retain transmission of up to 99.6%, and laser damage threshold of about 50 J/cm^2 at a wavelenth of 532 nm （1-on-1. 10 ns）
文摘A λ∕4–λ∕4 broadband antireflective(AR) coating is developed with a sol-gel dip-coating method. By adding SAR-5 organosilicon resin into a base-catalyzed silica sol top layer and treating at 300°C, a broadband AR coating used for blast shields with a high average transmission of 99.34%(450–950 nm) and good hydrophobicity(with a water-contact angle of 119°) was obtained. After being subjected to rubbing 50 times and being maintained at a relative humidity of around 95% for 50 days, the average transmission of the coating decreased by0.29% and 0.04%, respectively. This indicates that the organically modified silica(ORMOSIL) broadband AR coating has good abrasion resistance and humidity stability.
基金the Natural Science Foundation of Hubei Province(2019CFB575)the National Natural Science Foundation of China(51861145101)。
文摘Although perovskite solar cells(PSCs)have achieved encouraging efficiency,the photon loss at the substrate due to light reflection has not been well addressed.Light management is promising to reduce reflection loss and realize higher power conversion efficiency(PCE)of PSCs.Here,a bilayer antireflective coating(ARC)has been designed and coated onto the backside of the glass substrate of(FAPbI_(3))_(x)(MAPbBr_(3))_(1-x)PSCs to enhance photon harvesting and consequently the device efficiency.The bottom layer of the bilayer ARC is made from a silica polymer and the top layer is made from the mixture of hexamethyldisiloxane-modified mesoporous silica nanoparticles and a fluorinated silica polymer.By adjusting the refractive index and the film thickness of each layer according to a two-layer model,enhanced glass transmittance in a broadband wavelength range can be reached,with the maximum transmittance increasing from ca.90%to over 95%.With the bilayer ARC,the maximum short-circuit current density and PCE of(FAPbI_(3))_(x)(MAPbBr_(3))_(1-x)PSCs can be increased from 25.5 m A cm^(-2)and 22.7%to 26.5 mA cm^(-2)and 23.9%with negligible changes in fill factor and opencircuit voltage.This work presents a simple yet effective strategy to enhance the efficiency of solar cells employing bilayer antirefective coatings,which can be applied to other types of solar cells.
基金supported by National Natural Science Foundation of China(Nos.U1530148 and 61605188)
文摘Boron nitride(BN) nanosheets incorporated silica antireflective(AR) coating was successfully prepared on fused silica substrate to improve the antilaser-damage ability of transmissive optics used in high-power laser systems. The BN nanosheets were obtained by urea assisted solid exfoliation, and then incorporated into basic-catalyzed silica sols without any further treatment. The transmission electron microscope(TEM) images indicated that the BN nanosheets generally consisted of 2–10 layers. The antireflective BN/SiO_2 coating exhibited excellent transmittance as high as 99.89% at351 nm wavelength on fused silica substrate. The thermal conductivity 0.135 W · m^(-1)· K^(-1) of the BN/SiO_2 coating with 10% BN addition was about 23% higher than 0.11 W · m^(-1)· K^(-1) of the pure SiO_2 AR coating. The laser-induced damage threshold(LIDT) of that BN/SiO_2 coating is also 23.1% higher than that of pure SiO_2 AR coating. This research provides a potential application of BN/SiO_2 coatings in high-power laser systems.
基金This work was supported by the National High Technology Research and Development Program(“863”Program)of China(Grant No.2011AA050525)the Knowledge Innovation Program of the Chinese Academy of Sciences(CAS)(Grant Nos.KGCX2-YW-370 and KGCX2-EW-304-2)the National Natural Science Foundation of China(Grant no.21271177).
文摘A facile approach was developed to fabricate visible/near-infrared antireflective(AR),superhydrophilic and anti-fogging thin films on glass substrates.Glass substrate was first etched by H_(2)SiF_(6)-based vapor and then dip-coated sequentially in a base-catalyzed 20 nm SiO_(2)nanoparticles sol and an acid-catalyzed SiO_(2)sol.After an-nealing,the prepared thin film(named E/BSiO_(2)/ASiO_(2))not only showed good optical and wetting properties,but also exhibited excellent mechanical properties.The thin film has enhanced transmittance in the spectral range of UV to near-infrared.The maximum transmittance of E/BSiO_(2)/ASiO_(2)thin film coated glass substrate is 98.4%in 400-1200 nm and 96.1%in 1200-2500 nm,respectively.Comparing with blank glass substrate,the average transmittance increases by 5%in the wavelength range of 300-2500 nm.Meanwhile,the film showed good anti-fogging performance.SEM and AFM were employed to characterize the morphology of the thin film.The pre-pared thin film has potential application in various areas,like solar cells,windowpanes and eyeglasses,and may also find applications in membrane-based separation,selective catalysis and sensors.
基金This work is supported by the State Basic Research Project of China （Grant No. 2014CB931802）, the National Natural Science Foundation of China （Grant Nos. 21320102001, 21621001, 21571157） and the 111 Project.
文摘Antireflection surfaces and coatings have attracted considerable interests because they can maximize light transmittance of the substrates. In this work, zeolite antireflective （ZAR） coatings are prepared via layer-by-layer （LBL） assembly of MFI-type zeolite silicalite-1 and polyelectrolyte. A micro- and macroporous hierarchical structure was obtained which contributes to the antireflective property of the zeolite coatings. The light transmittance of the coating on quartz can achieve as high as 99.3% at 650 nm. Furthermore, a superh~/drophobic ZAR coating can be obtained by chemical modification with 1H,1H,2H,2H-perfluorooctyl-triethoxysilane. This work demonstrates that zeolites are excellent candidates as high transparent superhydrophobic coatings.
基金supported by the Strategic Priority Research Program of Chinese Academy of Sciences (No. XDA25020305)
文摘Different post-treatment processes involving the use of ammonia and hexamethyldisilazane(HMDS) were explored for application to 351 nm third harmonic generation SiO_(2)antireflective(3ω SiO_(2)AR) coatings for high power laser systems prepared by the sol-gel method.According to experimental analysis,the 3ω SiO_(2)AR coatings that were successively post-treated with ammonia and HMDS at 150℃ for 48 h and again heat-treated at 180℃ for 2 h(N/H 150+180 AR) were relatively better.There were relatively fewer changes in the optical properties of the N/H 150+180 AR coating under a humid and polluted environment,and the increase in defect density was slow in high humidity environments.The laser-induced damage threshold of the N/H 150+180 AR coating reached 15.83 J/cm;(355 nm,6.8 ns),a value that meets the basic requirements of high power laser systems.
基金This work was supported by the High-Tech Research and Development Program of China under Grant No.8638042.
文摘Porous SiO2 antireflective (AR) coatings are prepared from the colloidal silica solution modified with methyltriethoxysilane (MTES) based on the sol-gel route. The viscosity of modified silica suspensions changes but their stability keeps when MTES is introduced. The refractive indices of modified coatings vary little after bake treatment from 100 to 150℃. The modified silica coatings on Ti:sapphire crystal, owning good homogeneity, display prominent antireflective effect within the laser output waveband (750-850 nm) of Ti:sapphire lasers, with average transmission above 98.6%, and own laser induced damage thresholds (LIDTs) of more than 2.2 J/cm2 at 800 nm with the pulse duration of 300 ps.
基金The authors are grateful to the financial support by the National Basic Research Program of China （973 program, No. 2013CB934301）, the National Natural Science Foundation of China （Nos. 51531006 and 51572148）, the Research Project of Chinese Ministry of Education （No. 113007A）, and the Tsinghua University Initiative Scientific Research Program.
文摘Mechanical strength is an essential parameter that influences and limits the lifetime performance of antireflective （AR） coatings in optical devices. Speciflcally, amphiphobic AR coatings with reduced reflectance are of great significance as they considerably enlarge the range of fundamental applications. Herein, we describe the design and fabrication of amphiphobic AR coatings with reduced reflectance and enhanced mechanical resilience. Introducing a thin polytetrafluoroethylene （PTFE） layer on top of the bilayer SiOz coating via vapor deposition method makes it highly liquid repellent. We achieved reduced reflectance （〈 1%） over the entire visible wavelength range, as well as tunability according to the desired wavelength region. The fabricated film showed better thermal stability （up to 300℃） with stable AR efficiency, when an ultrathin dense coat of Al2O3 was deposited via atomic layer deposition （ALD） on the polymer-based bilayer SiO2 antireflective coating （P-BSAR）. The experimental results prove that the omnidirectional AR coating in this study exhibits multifunctional properties and should be suitable for the production of protective optical equipment and biocompatible polymer films for the displays of portable electronic devices.
基金supported by the National Natural Science Foundation of China(52074013,52374179)China Huaneng Group Science and Technology Project(HNKJ20-H87)+1 种基金Natural Science Foundation of Anhui Province(2208085ME125)Hefei Comprehensive National Science Center(21KZS216),which are gratefully appreciated.
文摘Coalbed methane(CBM)is a significant factor in triggering coal and gas outburst disaster,while also serving as a clean fuel.With the increasing depth of mining operations,coal seams that exhibit high levels of gas content and low permeability have become increasingly prevalent.While controllable shockwave(CSW)technology has proven effective in enhancing CBM in laboratory settings,there is a lack of reports on its field applications in soft and low-permeability coal seams.This study establishes the governing equations for stress waves induced by CSW.Laplace numerical inversion was employed to analyse the dynamic response of the coal seam during CSW antireflection.Additionally,quantitative calculations were performed for the crushed zone,fracture zone,and effective CSW influence range,which guided the selection of field test parameters.The results of the field test unveiled a substantial improvement in the gas permeability coefficient,the average rate of pure methane flowrate,and the mean gas flowrate within a 10 m radius of the antireflection borehole.These enhancements were notable,showing increases of 3 times,13.72 times,and 11.48 times,respectively.Furthermore,the field test performed on the CSW antireflection gas extraction hole cluster demonstrated a noticeable improvement in CBM extraction.After antireflection,the maximum peak gas concentration and maximum peak pure methane flow reached 71.2%and 2.59 m^(3)/min,respectively.These findings will offer valuable guidance for the application of CSW antireflection technology in soft and low-permeability coal seams.
