Visible Transmittance Research Articles

Effect of a radiative cooling emitter with indium tin oxide near-infrared heat mirror on the performance of photovoltaic module

ABSTRACT Recent research on cooling photovoltaic (PV) modules through radiative cooling methods has attracted significant interest, due to the temperature reduction that enhances the power generation of PV modules. This study uses a transparent-radiative heat mirror (TRHM) for cooling silicon PV modules, utilizing a combination of an indium tin oxide (ITO) layer and polydimethylsiloxane (PDMS) to enable visible light transmission while reflecting unnecessary heating photons. Fabricated by a low-cost method, the novelty honeycomb-like surface microstructure of PDMS enhances the material’s emissivity. Combined ITO layer with honeycomb-like PDMS, the film results in a reflectivity of 0.65 in the near-infrared range (1.1–2.5 μm, NIR) and an emissivity of 0.93 in the mid-far infrared range (8–13 μm, MIR). PV modules covered with TRHM (PV-TRHM) demonstrated a significant emissivity of 0.90 in MIR, leading to a temperature of 44.2°C, which has a 7.2°C reduction compared to the 53.6°C bare PV. Additionally, a 0.81% increase in power conversion efficiency (PCE) was achieved. These approaches hold promise for efficient PV heat management in engineering projects.

Period induced reflectance tuning in transparent gold metasurfaces

Gold (Au) nanodisk arrays are modeled and fabricated for tunable near infrared reflectance with high visible transmittance. Simulations are performed in the visible and near infrared regimes between 400 and 2000 nm with varying period of nanostructures. A progressive increase in period of up to three times the diameter of the nanodisks on polymer and quartz substrates is presented. As a result, an increase in visible transmittance with a decrease in near infrared reflectance peak intensity is observed. Modeling results exhibit a high average visible transmittance of 91.5% (400–700 nm) and average reflectance of 62.9% (750–2000 nm) with diameter (D) variations from D=120 nm to D=500 nm with a period (P) equal to twice the diameter, P=2D for a polymer substrate. Electric field intensities exhibit an increase with a decrease in the period between individual nanostructures for constant unit cell dimensions. Alongside simulations, electron beam lithography and evaporation processes are utilized for the patterning and fabrication. Optical characterizations including scanning electron microscopy (SEM) and atomic force microscopy (AFM) of selected metasurfaces on quartz are performed. For a specific period and diameter, the fabricated metasurfaces exhibit near infrared reflectance having a good agreement with the simulated results about plasmonic wavelengths. Such metasurfaces offer potential to be deployed for applications that require selective reflectance intensities in the near infrared range with high visible transmittance, such as controlled environment agriculture (CEA) or multi spectral near infrared sensing. With tunability over a broadband (750–2500 nm), this simple and fabrication-friendly model may be used as a theoretical guide in quantifying specific design parameters with varying light intensity configurations.

Single‐ and Double‐Layer Embedded Metal Meshes for Flexible, Highly Transparent Electromagnetic Interference Shielding

AbstractSimulation and experimental studies are carried out on single‐layer and double‐layer embedded metal meshes (SLEMM and DLEMM) to assess their performance as transparent electromagnetic interference (EMI) shielding. The structures consist of silver meshes embedded in polyethylene terephthalate (PET). As a transparent electrode, SLEMMs exhibit a transparency of 82.7% and a sheet resistance of 0.61 Ωsq−1 as well as 91.0% and 1.49 Ωsq−1. This performance corresponds to figures of merit of 3101 and 2620, respectively. The SLEMMs achieve 48.0 dB EMI shielding efficiency (SE) in the frequency range of 8–18 GHz (X‐ and Ku‐bands) with 91% visible transmission and 56.2 dB EMI SE with 82.7% visible transmission. Samples exhibit stable performance after 1000 bending cycles with a radius of curvature of 4 mm and 60 tape test cycles. DLEMMs consist of fabricating SLEMM on opposite sides of the substrate where the distance can be varied using a spacer. Simulations are performed to investigate how varying spacer distance between two layers of metal meshes influences the EMI SE. DLEMMs are fabricated and achieved an EMI SE of 77.7 dB with 81.7% visible transmission. SLEMMs and DLEMMs may have a wide variety of applications in aerospace, medical, and military applications.

Green zinc/galactomannan-based hydrogels push up the photovoltage of quasi solid aqueous dye sensitized solar cells

In the present work, we implement environmentally friendly water-based Quasi-Solid Electrolytes (QSE) for Dye Sensitized Solar Cells (DSSCs), displaying an unprecedent open circuit voltage (VOC) as high as 750 mV. The production of the hydrogel for QSE-DSSCs is achieved by exploiting the concept of fully green design and fabrication, through the selection of components such as the natural polysaccharide galactomannan (GM), biocompatible zinc salts, and the employment of eco-friendly synthetic procedures to produce the hybrid gelating agents. In the process, moderate temperature (<40 °C), only aqueous solutions are employed, and, at most, ethanol is used in some phases of the procedure. Depending on the type of the initial salt, either zinc hydroxysulfate lamellae or zinc oxide nanoparticles are created within the gel matrix, with a more extended nanoporous structure in the latter case. The nanostructures and the gels are investigated by multiple techniques, including X-ray diffraction (XRD), infrared spectroscopy (IR), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). Upon ensuing addition of I-/I3- redox mediator and assembling of the device, state-of-the-art aqueous QSE-DSSCs are achieved. The latter couples a 2 % efficiency (limited by charge diffusion as proved by Electrochemical Impedance Spectroscopy) with a good Average Visible Transmittance (AVT), and Light Utilization Efficiency (LUE), a couple of coveted features in wave-selective or semi-transparent devices. Finally, Linear Response-Time Dependent DFT (LR-TDDFT) simulations are carried out on a model iodine/iodide layered zinc hydroxy sulphate structure towards a better understanding of the mechanism responsible for the high AVT.

Impact of production methods on properties of natural rosin added polylactic acid/sodium pentaborate and polylactic acid/calcium carbonate films

Nowadays biopolymers play an important role in packaging materials due to their protection properties against physical and chemical degradation or mechanical resistance. In this study, sodium pentaborate anhydride (B5NaO8), eggshell (CaCO3) nanoparticles, and natural rosin additives were introduced to pure PLA to produce a biofilm protecting from UV rays. The impact of the preparation method of hybrid biocomposite films was carried out based on the polymer casting method and using in the first case only magnetic mixing whereas magnetic mixing coupled with ultrasonic homogenizer was used in the second case. All biocomposite films were obtained for a nanoparticle content fixed at 7.5 wt% and various rosin rates (1, 5, 10, and 40 wt%). This study aims to expand the UV protection zone in PLA films. The thermal and mechanical properties, transmittance of UV–visible rays, microstructure analysis, and contact angle values were evaluated to detect the effect of the preparation method on the final properties. The results showed that the homogeneous distribution of the particles was more effective using an ultrasonic homogenizer. The increase of the rosin amount exhibited a reduction of the UV–visible light transmittance and the wettability was observed, demonstrating a potential use of these films in packaging.

Photonic crystal microspheres: Synthesis, characterization, and applications in colored contact lenses

Structural colors arise from the interaction between light and ordered structural materials, making them the ideal choice for colored contact lenses. This study utilized a fast, large-scale synthesis method for silica photonic crystal microspheres, introducing carbon black to enhance the structural coloring effect. The sintering process strengthened the cohesion between particles, increasing their strength and expanding their range of applications. This approach successfully prepared SiO2 photonic crystal inks with structural colors to produce contact lenses through a pad printing technique. In particular, the coloration is solely achieved using SiO2 and carbon black without other organic species. The resulting structural color blue contact lenses exhibit high light transmittance and vivid structural colors. Furthermore, the following necessary properties were me: oxygen transmittance, visible light transmittance, hydrophilicity, and lipid and protein adsorption of the contact lenses. Cell viability experiments indicate that contact lenses made from this material are biocompatible. The results illustrated that these as-prepared lenses are promising candidates for traditional colored contact lenses.

Translucent superhydrophobic coating for murals protection

This study aims to protect murals by a translucent and superhydrophobic coating using a one-step spraying process, which offers simplicity, efficiency, and cost-effectiveness, while preserving the mural's visual appeal and safeguarding against moisture. Despite numerous advancements in cultural relic conservation, the application of super-hydrophobic coatings for mural preservation remains a novel approach. The coating consists of acrylic resin (Paraloid B72), nano-silica, and polydimethylsiloxane (PDMS). The optimal amounts of silica and PDMS were 3 g each in a basal solution containing 12 g of acrylic resin dissolved in 88 mL of xylene. The resulting composite coating displayed exceptional water repellency, as indicated by a contact angle of 165.5° and a rolling angle of approx. 7°. As a result, the moisture absorption of the mural decreased significantly from ∼53% to ∼5% after the application of the superhydrophobic coating. The coating had minimal impact on the water vapor permeability of the mural, with a ca. 13% decline rate. The coating is translucent with a visible transmittance of approximately 60%. Therefore, the coated mural maintains its original appearance with minimal changes. Furthermore, the superhydrophobic properties of the coating remain intact even after undergoing five cycles of high-low temperature fatigue tests, 196 hours of ultraviolet irradiation, or seven cycles of sand impacting.

Thermochromic Nanocellulose Films for Temperature-Adaptive Passive Cooling.

Energy efficiency in habitation spaces is a pivotal topic for maintaining energy sufficiency, cutting climate impact, and facilitating economic savings; thus, there is a critical need for solutions aimed at tackling this problem. One viable approach involves complementing active cooling methods with powerless or passive cooling ones. Moreover, considerable scope remains for the development of passive radiative cooling solutions based on sustainable materials. Cellulose, characterized by its abundance, renewability, and biodegradability, emerges as a promising material for this purpose due to its notable radiative cooling potential exploiting the mid-infrared (MIR) atmospheric transmission window (8-13 μm). In this work, we propose the utilization of thermochromic (TC) materials in conjunction with cellulose nanofibrils (CNF) to confer temperature-dependent adaptivity to hybrid CNF films. We employ a concept where high reflection, coupled with MIR emission in the heated state, facilitates cooling, while high visible light absorption in the cold state allows heating, thus enabling adaptive thermal regulation. CNF films were doped with black-to-leuco TC particles, and a thin silver layer was optionally applied to the films. The films exhibited a rapid transition (within 1 s) in their optical properties at ∼22 °C, becoming transparent above the transition temperature. Visible range transmittance of all samples ranged from 60 to 90%, with pronounced absorption in the 8-13 μm range. The cooling potential of the films was measured at 1-4 °C without any Ag layer and ∼10 °C with a Ag layer. In outdoor field testing, a peak cooling value of 12 °C was achieved during bright sunshine, which is comparable to a commercial solar film. A simulation model was also built based on the experimental results. The concept presented in this study extends beyond applications as standalone films but has applicability also in glass coatings. Overall, this work opens the door for a novel application opportunity for green cellulose-based materials.

Enhancement of damage resistance of transparent Li2O-Al2O3-B2O3 glass by crystallization

Aluminoborate glasses exhibit remarkable crack-resistance properties, rendering them a promising material for cover glasses in portable electronic devices. However, their usage has been hindered by their relatively low hardness. To address this challenge, a parent glass with 11 Li2O-30 Al2O3-55 B2O3-2 TiO2-2 P2O5 (wt%) was prepared using a melt-cast method. Heat treatment at 575 °C yielded a glass-ceramic (G-575) with a Vickers hardness of 6.51 GPa, 40.91 % higher than the parent glass due to structural densification and Li(Al7B4O17) crystalline phase precipitation, improving indentation fracture toughness from 0.97 to 1.79 MPa·m1/2. Additionally, the glass-ceramics demonstrated a visible transmittance of approximately 85 % and a cracking resistance (CR) value of 14.8 N. Scratch tests conducted at a constant force revealed that the comprehensive damage resistance of glass-ceramics surpassed that of the parent glasses, making it a promising cover glass material.

Fluorine-doped ATO NCs with enhanced LSPR effect for smart windows with adaptive solar modulation

Smart windows with excellent near-infrared (NIR) light shielding capacity and controlled visible light transmittance are expected to reduce building energy consumption and improve indoor comfort. However, the ability of current thermochromic materials to regulate solar gain with the tunable extinction of phase-change materials is still far from optimum. In this work, an fluorine (F)-doped ATO (FATO) nanocrystals (NCs) are designed as a photothermal material to optimize the solar modulation of thermochromic hydrogels. F ion doping can modify the electronic structure of ATO, resulting in a high concentration of oxygen vacancies and free electrons, thereby enhancing the NIR absorption performance and photothermal conversion performance of the ATO NCs. On this premise, the designed smart window based on FATO NCs and thermochromic hydrogels exhibits the remarkable features of excellent NIR shielding, high initial visible transmittance and fast response speed. The window is capable of shielding 99.5% of the solar radiation from 300 to 2500 nm and permitting 75.0% of initial visible light. Moreover, the simulated indoor temperature of the smart window was 17.2 °C lower compared with the black one, demonstrating potentials in practical application of building energy saving.

KCA/Na2SiO3/PNIPAm hydrogel with highly robust and strong solar modulation capability for thermochromic smart window

Thermochromic smart windows have strong competitive advantages in the realm of building energy conservation. However, achieving thermochromic smart window with a lower critical solution temperature (LCST), high solar modulation (ΔTsol), and excellent visible light transmittance (Tlum) remains a great challenge. Here, a novel composite hydrogel based on polydiisopropylacrylamide (PNIPAm) doped with carrageenan (KCA) and Na2SiO3 was developed for high-performance smart window. The lower LCST of PNIPAm was precisely tuned in a range from 25 °C to 28 °C by controlling the content of added Na2SiO3. The inclusion of KCA diminishes agglomeration within the gel system and enhances both Tlum and ΔTsol. As a result, the KCA/Na2SiO3/PNIPAm exhibits a high Tlum (87.37 %), ΔTsol (69.65 %), a lower LCST (27.2 °C), and a high atmospheric window emissivity (0.962). The smart window achieves temperature drop of 12.3 °C under direct sunlight, and keeps highly stable even after 100 cycle tests high and low-temperature durability due to its robust solar modulation capability. This work offers valuable insights for developing high-performance and robust thermochromic smart windows and holds promising applications in building energy conservation.

A Multistate Thermoresponsive Smart Window Based on a Multifunctional Luminescent Solar Concentrator.

Conventional luminescent solar concentrators (LSCs) usually only have the ability to absorb solar energy and convert it to electricity but are not able to regulate the transmitted light. Herein, a multistate thermoresponsive smart window (SW) based on LSC has been fabricated, in which the stimuli-responsive host layer consists of polydimethylsiloxane (PDMS) and ethylene glycol solution (EGS) microdroplets stacking with LSC layer-based on near-infrared (NIR) CuInSe2-xSx/ZnS core/shell quantum dots (QDs) and PDMS matrix. As-synthesized CISSe/ZnS QDs with broad NIR absorption in LSC exhibit controllable emission spectra over 833-1088 nm and high photoluminescence (PL) quantum yield from 45 to 83%. Coupling with Si solar cells as a reference, optimized LSC-SW devices with dimensions of 5 × 5 × 0.9 cm3 exhibit higher power conversion efficiency (PCE) of 1.19-1.36% with increased temperature from 0 to 50 °C than those of sole LSC and SW devices. The corresponding visible light transmissions are regulated from 75.1 to 48.1% accordingly. The improvement of PCEs in an opaque state is mainly due to enhanced absorption of QDs originating from rescattered photons from the EGS/PDMS layer, leading to more emitted photons reaching photovoltaics. This work is expected to bring up new opportunities for applications in greenhouses, building facades, and energy-efficient smart windows.

Enhanced adhesive and mechanically robust silicone-based coating with excellent marine anti-fouling and anti-corrosion performances.

Poly(dimethylsiloxane) (PDMS) is widely used in marine antifouling coatings due to its low surface energy property. However, certain drawbacks of PDMS coatings such as poor surface adhesion, weak mechanical properties, and inadequate static antifouling performance have hindered its practical applications. Herein, condensation polymerization is utilized to prepare PDMS-based polythiamine ester (PTUBAF) coatings that consist of PDMS, polytetrahydrofuran (PTMG), 2, 3, 5, 6-tetrafluoro-1, 4-benzenedimethanol (TBD) as the main chains and isobornyl acrylate(IBA) as the antifouling group. The surface adhesion to the substrate is enhanced due to the hydrogen bond between the coated carbamate group and the hydroxyl group on the surface of the substrate. Mechanical properties of PTUBAF are significantly improved due to the benzene ring and six-membered ring biphase hard structure. The strong synergistic effect of bactericidal groups and low surface energy surface endows the PTUBAF coating with outstanding antifouling performance. Due to the low surface energy surface, the PTUBAF coatings are also found to possess excellent anti-corrosion. Furthermore, since the PTUBAF coatings exhibit a visible light transmittance of 91 %, they can applied as protective films for smartphones. The proposed method has the potential to boost the production and practical applications of silicone-based coatings.

Long-lived electrochromic device with protonated viologen and Poly(ethylenedioxythiophene-carbazole)/Prussian blue composite for smart windows

A complementary electrochromic device (ECD) configuration featuring a protonated viologen (VNH2+) as the cathodically coloring electrochrome and a composite of poly(ethylenedioxythiophene-carbazole) (i.e. poly(EDOT-Cz)) and Prussian blue (PB) as the anodically coloring electrochrome marks the first implementation of this innovative high contrast device. A comparative analysis of VNH2+//poly(EDOT-Cz) and VNH2+//poly(EDOT-Cz)/PB ECDs demonstrates a superior integrated visible light transmission modulation (ΔT) of 50.4%, versus 76.7%, higher diffusion coefficient of 4.4 × 10−11versus 3.9 × 10−10 cm2 s−1, higher coloration efficiency (CE) of 424 versus 562 cm2 C−1 (at 550 nm), faster color-bleach switching times of (7.0 and 4.0 s) versus (1.2 and 1.0 s) and a CIE chromaticity coordinate corresponding an intense deep blue state (y: 0.058 versus 0.218) achieved with the composite relative to the pure polymer. The VNH2+//PB ECD also shows lower CE (69 cm2 C−1) and slower coloration-bleaching kinetics (20 and 2 s) compared to the composite based ECD. In addition, long-term cycling stability attained for the VNH2+//poly(EDOT-Cz)/PB ECD, whereby it endures 5000+ color-bleach cycles without showing any major deterioration in optical modulation or switching kinetics underscores the suitability of the composite based ECD for practical smart window applications.

Understanding the effects of annealing induced structural transformations on the UVC absorbance and other optical properties of RF sputter deposited Ga2O3 thin films

Gallium oxide (Ga2O3) is a transparent material with high absorption in the UVC region of the electromagnetic spectrum and hence is a very important candidate in the field of short wavelength optical device fabrication. A proper understanding of the different optical parameters is necessary for developing more efficient coatings and devices. In this work, changes in the optical behavior of Ga2O3 thin films due to post-deposition annealing (at temperatures 300 °C–900 °C) are discussed in detail. Structural, surface morphological and compositional modifications of the films are identified using the x-ray diffractometer, scanning electron microscopy and x-ray photoelectron spectrometer techniques, respectively. At 900 °C, a highly stable monoclinic β phase of Ga2O3 is obtained. The optical transmittance spectra acquired using UV–Vis spectroscopy indicate an improved UVC absorbance of the β-Ga2O3 films with an excellent visible transmittance (>80%). The structural transformation from amorphous to crystalline β-Ga2O3 phase and the associated reduction in defect density is found to modify other optical attributes, like the bandgap energy, Urbach energy, dispersion parameters, etc.

Sustained Delivery of Olopatadine from Vitamin-E Loaded Contact Lenses.

Purpose: Topical antihistamines, such as olopatadine hydrochloride, an H1 receptor antagonist, are commonly prescribed for treating allergic conjunctivitis. Drug delivery via eye drops has many deficiencies including a short residence time due to tear drainage via the nasolacrimal duct, which results in a low bioavailability and potential for side effects. These deficiencies could be mitigated by a drug-eluting contact lens such as the recently approved ACUVUE® THERAVISION™ WITH KETOTIFEN which is a daily disposable etafilcon, a drug-eluting contact lens with ketotifen (19 μg per lens). Here, we investigate the feasibility of designing a drug-eluting lens with sustained release of olopatadine for treating allergies using an extended wear lens. Methods: Nanobarrier depots composed of vitamin-E (VE) are formed through direct entrapment by ethanol-driven swelling. The drug-loaded lenses are characterized for transparency and water content. In vitro release is measured under sink conditions and fitted to a diffusion control release model to determine diffusivity and partition coefficient. Results: In vitro studies indicate that ACUVUE OASYS® and ACUVUE TruEye™ lenses loaded with ∼0.3 g of VE/g of hydrogel effectively prolong olopatadine dynamics by 7-fold and 375-fold, respectively. Incorporation of VE into the lenses retains visible light transmission and other properties. Conclusion: The VE incorporation in commercial lenses significantly increases the release duration offering the possibility of antiallergy extended wear lenses.

Adaptive Thermal Management Radiative Cooling Smart Window with Perfect Near-Infrared Shielding.

The architectural window with spectrally selective features and radiative cooling is an effective way to save building energy consumption. However, architectural windows that combine both functions are currently based on micro-nano photonic structures, which undoubtedly hinder their commercial application due to the complexity of manufacture. Herein, a novel tunable visible light transmittance radiative cooling smart window (TTRC smart window) with perfect near-infrared (NIR) shielding ability is manufactured via a mass-producible scraping method. TTRC smart window presents high luminous transmittance (Tlum = 56.8%), perfect NIR shielding (TNIR = 3.4%), bidirectional transparency adjustment ability unavailable in other transparent radiative coolers based on photonic structures (ΔTlum = 54.2%), and high emittance in the atmospheric window (over 94%). Outdoor measurements confirm that smart window can reduce 8.2 and 6.6°C, respectively, compared to ordinary glass and indium tin oxide (ITO) glass. Moreover, TTRC smart window can save over 20% of annual energy in the tropics compared to ITO and ordinary glass. The simple preparation method employed in this work and the superior optical properties of the smart window have significantly broadened the scope of application of architectural windows and advanced the commercialization of architectural windows.

Robust alkali-resistance of cover glass's UV-shielding and strengthening sol-gel coatings by tailoring the coupling between SiO2 and 2,2′,4,4′-tetrahydroxybenzophenone

Cover glass with UV-shielding function is important to mobile displays such as mobile phones and tablet PCs, as well as flexible photovoltaic cells. UV-shielding over 90 % while visible light transmittance over 90 % is a rather difficult technical challenge for cover glass. In this report, robust alkali-resistance of display cover glass's UV-shielding and strengthening sol-gel coatings have been successfully prepared, using 2,2′,4,4′-tetrahydroxybenzophenone (BP-2), γ-(2,3-epoxypropoxy) propyltrimethoxysilane (KH560) and tetraethyl orthosilicate (TEOS) as raw materials. The coupling between SiO2 and BP-2 was tailored by using a condensation reflux method for the mixture of BP-2 and KH560. Compared to blank glass (0.7 mm thickness), UV-shielding (UV-A and UV-B) of the coated glass (coated on one side, 3 μm thickness of coating) increases significantly from 13.43 % to 99.93 %, while the visible light transmittance (380–780 nm) changes only slightly from 91.87 % to 90.16 %. Moreover, the bending strength of the coated glass improves by 52 MPa, and the drop ball impact resistance increases by 16 %. After alkali corrosion, glass's UV-shielding with the BP-2/SiO2 coupling or uncoupling coatings is 90.03 % or 80.03 %, respectively. The BP-2/SiO2 coupling coatings significantly improve alkaline corrosion resistance. Fourier transform infrared spectroscopy analysis confirms that BP-2 is chemically grafted into the SiO2 grid of the coating, which contributes to the robust alkali-resistance. Demonstrated by the finite element simulation, the strengthening effect originates from the repair of cracks on the surface of glass by the coating. The coating presents its application possibility on cover glass.

Dithienopyran-based narrow-bandgap donor polymers: Unveiling the potential for semitransparent organic solar cells with enhanced NIR absorption

Semitransparent organic solar cells (ST-OSCs) have recently received considerable attention in the field of photovoltaics owing to their great potential in applications such as building-integrated photovoltaics, self-powered greenhouses, and vehicle coatings. Because the near-infrared (NIR) region is an invisible region whose photon content is higher than that of the visible region, it is preferable to apply photoactive materials with narrow bandgaps in ST-OSCs. Tremendous efforts have been made to develop narrow-bandgap non-fullerene acceptors, however, donor polymers with NIR absorption ability for efficient ST-OSCs have rarely been reported. In this study, two novel narrow-bandgap donor polymers, PDTP-TBT and PDTTP-TBT, are designed and synthesized. Both polymers exhibit strong NIR absorption and high transmittance in the visible region, suggesting their potential for use in ST-OSCs. An opaque OSC with a PDTTP-TBT-based photoactive layer achieves a higher power conversion efficiency (PCE) of 8.87% than a PDTP-TBT-based OSC (PCE of 3.65%) due to its better charge transport characteristics. Furthermore, an ST-OSC using PDTTP-TBT-based blend film exhibits a PCE of 6.72%, average visible transmittance of 43.9%, and light utilization efficiency of 2.95%.

Preparation study and simulation of high transmittance W–Sn–Zr Co-doped VO2 thin films prepared by sol-gel method for energy-saving smart windows

The thermochromic properties of vanadium dioxide (VO2) hold great promise for applications in smart glass windows. VO2 films exhibit a high phase transition temperature (Tc), low visible transmission (Tlum), and low solar modulating ability (ΔTsol), making them inadequate for the requirements of smart glass windows. While some improvement in VO2 film performance can be achieved through single-element doping, these limited enhancements still fall short of ideal results. Therefore, there is a pressing need for the improvement of VO2 films. In this study, we utilized the sol-gel method to prepare VO2 samples simultaneously doped with three elements: W, Sn, and Zr. Microscopic characterization confirmed the successful incorporation of these elements. Optical measurements, including ultraviolet–visible–near-infrared spectroscopy, were conducted to assess the optical properties of the films. Ultimately, outstanding Tlum (69%) and ΔTsol (14%) were achieved, along with an appropriate Tc (27.6 °C). Energy consumption simulations were performed using the EnergyPlus model with experimental data, revealing that compared to conventional glass, VO2 glass reduces total cooling energy consumption by 9.8%. In comparison to previous work, the multi-element-doped films push the performance limits of VO2 films, offering a viable approach for fabricating superior VO2 smart glass windows.