Multi-resonance thermally activated delayed fluorescence (MR-TADF) materials, based on polycyclic aromatic frameworks, have shown promise in achieving narrow-band emission and high luminous ...efficiency. In this study, we investigate the performance of a blue MR-TADF material, 2′2'2''-(1,3,5-triazine-2,4,6-triyl) tris(9-(2-(naphthalen-2-yl)phenyl)-9H-carbazole) (TBN-TPA), in tandem OLED devices. Single emitter unit and two emitter unit tandem OLED devices with blue MR-TADF material were explored with optical modeling simulation. More importantly, the tandem architecture assists in realizing narrow-band emission and high color purity via optical interference and microcavity effects, which are essential for meeting BT 2020 standards. TBN-TPA achieves narrow full width at half maximum down to 24 nm and CIE coordinates approaching the blue region in tandem devices. Our work highlights the significant advantages of combining tandem architectures and emerging MR-TADF emitters for developing high-performance OLEDs with both high efficiency and wide color gamut. This is the first demonstration of using tandem OLED architecture to improve both efficiency and color purity of a blue multi-resonance TADF emitter. Further research on optimizing tandem structures and designing advanced MR-TADF materials will promote the applications of OLED displays.
•Single-emissive and dual-emissive layer blue MR-TADF tandem OLED devices were explored with optical modeling simulation.•The tandem architecture assists in realizing narrow-band emission and high color purity via optical interference and microcavity effects with a narrow FWHM of 24 nm and CIE coordinates approaching the blue region in tandem devices.
•Power Conversion efficiency simulation.•Optical simulation.•Organic solar cells.
This work presents the simulation of the power conversion efficiency of organic solar cells (OSCs), as well as the ...optimization of the thickness of active layer for better efficiency. The simulated OSCs uses P3HT: PCBM polymer as an active layer. The simulation makes use of an optical model, present in the literature, based on the transfer matrix method that allows calculate the transmission and reflection in each layer of the device. The comparison of the simulated efficiency results with real data from literature shows an average variation of 16%.
Although active-matrix organic light-emitting diode displays (AMOLEDs) have been widely applied, effective optical out-coupling techniques possessing both integration compatibility and image quality ...remain highly desired for further improving their efficiency and power consumption performances. In our previous simulation studies, a 3-dimensional (3D) reflective pixel structure filled with a patterned high-index material was proposed for boosting light extraction efficiency of common top-emitting AMOLED pixel devices. In this work, we conducted experimental studies on the proposed 3D OLED pixel configuration to validate the simulation and design. 3D OLED pixel devices with varied pixel dimensions were implemented and their structures, electrical properties, efficiencies, and EL characteristics were characterized. Significant efficiency gains were obtained with the μm-scale reflective 3D pixel devices and experiment results well corroborated multiscale optical simulation results, confirming effectiveness of the 3D OLED pixel for enhancing light extraction of OLED displays.
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•Implemented reflective 3D OLED pixel configurations for enhancing light extraction of OLED displays.•Significant gain in light extraction was obtained with reducing pixel sizes.•Experiment results validate optical simulation and effectiveness of 3D pixel for light extraction.
•A dynamic shadow model was established for the façade.•Improved model of PV-blind façade was established and experimentally validated.•The system shadow distributions and shading coefficient maps ...are formulated.•“U”, “M”, “Λ”, and “W” shaped error curves are identified.•Impact of façade configurations and geographical locations are revealed.
PV-blind embedded glazing façade is a promising façade system with multi-function of flexible daylighting control, power generation and heat gain/loss reduction. It is investigated in some studies before, but usually for model simplification, the building shadow is not considered, even it is not clear how the building shadow affects simulation accuracy and system performance. In this study, an improved thermal-electrical-optical model is proposed with full consideration of dynamic complex shading effects from building eave, window frame and PV-blinds. A series of experimental tests are conducted to verify the system model. The newly proposed model is used as an important tool to better understand impacts of complex shading effects. The results show some new and valuable findings: (a) The radar map of shading coefficient is rotating clockwise with increased local latitude and it is shifting from west to east with increased local longitude, which is in accordance with the varied local longitude; (b) The “U”, “M”, “Λ”, and “W” shaped error curves are, for the first time, identified in simulation if the complex shading effects are not considered and the annual simulation errors are about 40–120% for optical model, 12.5–27% for thermal model and as high as 10–18 times for electrical model; (c) The power generation and thermal performance are greatly affected by façade orientations and blind arrangements. And when the PVBGF system is applied to cities in different zones, the overall system performance is heavily sensitive to the local latitude than local longitude.
•Optical simulation to optimize and verify the geometrical structure parameters of POF.•Simple and effective preparation method of fiber optic sensor.•Respiratory monitoring and evaluation under ...different motion conditions.•Comparison of monitoring accuracy between smart respiratory monitoring garment form and commercial respiratory sensors.
In this paper, a grooved polymer optical fiber (POF) sensor embedded in polyurethane is to monitor human respiratory rate. First, the luminescence characteristics of POFs with different numbers, depths, and lengths of grooves, and the coupling effect of fiber groups (one each for luminescent and receiving POFs) are investigated using geometric optical simulations. The results show that the luminescence characteristics of the groove fibers are proportional to the depth and number of grooves, and the coupling effect is related to the arrangement of the fiber groups. Then, the geometrically optimized fluted fibers are embedded in polyurethane in different arrangement groups to prepare fiber optic sensing elements, and tensile tests are performed to compare the coupling effects to verify the accuracy of the simulation conclusions. The optimal arrangement of the sensor fiber with the tensile region is also analyzed and positioned to significantly improve the tensile sensitivity of the sensor. Finally, the sensor device is introduced in the form of a belt for human respiratory monitoring, which can track the respiratory signal in real time under different motion states. Evaluation experiments on three subjects show that the device has a strong correlation with the simultaneous monitoring results of commercial respiratory sensors, with an accuracy of 69.4% for respiratory rate monitoring in different states and 83.3% for respiratory rate monitoring in sitting and standing states.
In greenhouses, sweet peppers with adequate stem density can improve fruit yield. However, a higher number of stems may negatively affect growth and fruit yield due to higher fruit load and lower ...light interception. For this reason, supplemental lighting has widely been applied to greenhouse cultivation, but it is not easy to analyse its effect due to the high spatial complexity of canopy components. This study aimed to analyse the growth and yield of sweet pepper plants with different stem densities under supplemental lighting and to evaluate the canopy light profile and photosynthesis using ray-tracing simulation with 3D plant models. Supplemental lighting using high-pressure sodium lamps (SL) started from December 1, 2020, to May 25, 2021. 3D plant models were constructed using a 3D scanner at 13 and 20 weeks after transplanting. Crop photosynthesis was calculated from simulated light interception using the modified FvCB model. Under SL, the dry weight of plants and the total fruit yields per plant were significantly higher than under natural light (NL). The 3D analysis enabled us to accurately estimate the light interception and photosynthetic rate of the two and three stem plants. The simulation results showed that the total photosynthetic assimilation was improved under SL, resulting in improved fruit production. With simulated canopy light profiles in the greenhouse, annual operation costs and energy consumption for fruit yields of the plants with different stem densities could be estimated. This method could help determine stem density and supplemental lighting levels during crop cultivation in greenhouses.
•Stem number (SN) and supplemental lighting (SL) were used to improve the crop yield.•Combined effect of SN and SL on growth and yield of sweet peppers was analysed.•SL with high SN promoted the early fruit yield but decreased the late harvests.•With the ray-tracer, canopy light interception and photosynthesis was estimated.•Annual energy consumption and lighting costs under SN and SL could be estimated.
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•A new design of Solar Parabolic Dish Desalination System (SPDDS) was proposed.•Τhermal performance of SPDDS was investigated experimentally and numerically.•Optical simulation for ...SPDDS was performed using COMSOL model.•The model showed that thermal performance of absorber within glass enclosure was promising.•The maximum daily thermal efficiency of SPDDS was calculated to be 36.04%.
The objective of the present study is to construct a cheap, new design of small-scale solar parabolic dish desalination system made from reused local recyclable materials without complex parts and power source with advantageous approach due to its unique configuration. The desalting system including a new design of cleanable vessel acts as a boiler that accommodate inside a glass box to minimize the heat losses by the wind. The proposed system was investigated by experiments and numerical model. Moreover, the optical efficiency of the system was simulated using COMSOL model. The experimental data using different levels of salt concentrations and brine masses was compared to those of numerical to validate the model. The model validation revealed that the mean bias error and mean percentage error for brine were −1.05 °C and 0.86%, respectively, while the maximum predicted concentration ratio reached ∼16,000 and ∼9000 for ideal and real reflectors, respectively. The experimental results of were compared to those numerical to validate the model using different levels of salt concentrations and brine masses. The obtained daily average values of radiative heat transfer coefficient proved the effective role of the glass box and vessel in reducing the heat losses to surroundings. At brine mass of 0.75 kg and salt concentration of 15 g/kg, the increase of the salt concentration from 0 to 200 g/kg decreases numerically the daily productivity and daily efficiency from 500 to 320 ml/m2.day and from 88.60 to 19%, respectively. Experimentally, the maximum instantaneous and daily thermal efficiency were found to be 53.40% and 36.04%,respectively, while the cost of freshwater production from the proposed system was 0.64 $/l.
•Dimensional variations lead to drastic deviations in the optical performance.•In-process inspection technologies are essential for zero-defects manufacturing.•Confocal microscopy provides fast, ...non-destructive 3D measurements for research.•X, Y axes uncertainty has higher impact on optical functionality of the diffuser.•Simulations support analytical calculations of diffraction angles and irradiance.
The production of high-value components containing functional micro- and submicron-scale features requires the implementation of high-quality in-process inspection technologies to guarantee zero-defect manufacturing, boosting the transition to digital manufacturing. In the present study, the impact of the measurement uncertainty assigned to surface micro- and submicron-structures on the optical performance of a one-dimensional diffraction grating was determined. Thus, 3D confocal microscopy was selected as an inspection technology, introducing measuring data and uncertainty values on an optical simulation model to evaluate the influence of those magnitudes on the irradiance profile of a light beam at a target plane after passing through the diffraction grating. To achieve this goal, the calibrated areal standards have been used in addition to good practice guides for instrument calibration combined with optical modeling to simulate the functional behavior of the optical device. Results proved that changes of hundreds of nanometers in the lateral dimensions of the grating profile lead to drastic deviations in the irradiance profile and, thus, deviation in the optical performance. Hence a change in the period and the structure width of the step grating to the limits of the calculated uncertainty (Nominal Period ± ux,y) supposes a change of down to a 50 % of decrease in the maximum peak of the irradiance profile detected. Thanks to these results, it is possible to define a range in the grating device's performance depending on the dimensional surface characterization and its uncertainty. Moreover, an in-situ measurement approach has been designed for further product quality control.
Aluminium titanium oxynitrides were studied as candidate materials for high temperature absorbers in solar selective coatings due to their excellent stability and their tuneable optical behaviour. A ...set of individual AlyTi1−y(OxN1−x) layers with different oxygen content was prepared by cathodic vacuum arc (CVA) deposition. The composition, morphology, phase structure and microstructure of the films were characterized by elastic recoil detection (ERD), scanning and transmission electron microscopy and X-ray diffraction. An fcc phase structure is found in a broad compositional range of AlyTi1−y(OxN1−x). Simultaneously, sample microstructure and morphology undergo systematic changes from a columnar growth to the development of a heterogeneous structure with spherical nanoparticle inclusions when the oxygen concentration is increased. The optical properties were determined by spectroscopic ellipsometry and UV–Vis–NIR and FTIR spectrophotometry. A comprehensive analysis of the film properties allowed an accurate modelling of the optical constants of the AlyTi1−y(OxN1−x) in the whole wavelength range of solar interest (from 190nm to 25µm). It points to a transition from metallic to dielectric behaviour with increasing oxygen content. Consequently, it is demonstrated that the optical properties of these AlyTi1−y(OxN1−x) deposited films can be controlled in a wide range from metallic to dielectric character by adjusting the oxygen concentration, opening a huge range of possibilities for the design of solar selective coatings (SSC) based on this material. Complete SSC, including a TiN layer as IR reflector, were designed by applying optical simulations, obtaining excellent optical selective properties of α = 94.0% and εRT = 4.8%.
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•Design of high-temperature solar selective coatings based on AlyTi1-y(OxN1-x).•α=94.0% and εRT = 4.8%.•Exhaustive compositional, microstructural and morphological characterization.•Accurate modelling of optical constants in the whole wavelength range of interest.•Optical properties controlled (metal to dielectric) by tuning oxygen concentration.
Among the many requirements to modern high-performance automotive windshields is to provide a good visibility while limiting the amount of sunlight heat energy entering the cabin. This is ...traditionally achieved by incorporating a sputter deposited silver-inclusive solar-control coating into the windshield laminate to boost its reflection in the near-infrared. Such a coating can also serve as a heating element for the windshield deicing. This article discusses the benefit of using an additional coating deposited on the innermost surface of the windshield to further improve its thermal insulation properties, particularly in the mid-infrared spectral region. A systematic approach is employed to prioritize the contribution of sputter deposition parameters and thin-film design elements to the enhanced combined optical and electrical attributes of both coatings. Refined simulation models are presented and put to the test to attain the required level of visible transmittance. The additional benefit of adding the thermal coating for an improved color neutrality is also discussed.
•A low-emissivity thin-film stack can be added to a windshield along with a solar-control coating.•Both coatings must thoroughly be optimized to meet the regulatory standard for combined visible transmittance.•Optimization includes retuning both thin-film stacks and refining their optical models.•The optimized laminate is shown to achieve enhanced optical, electrical, and thermal properties.•The improved performance can be a differentiator for high-end cars in thermal comfort of vehicle occupants.
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