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An unstructured Monte Carlo ray-tracing method for solving radiative heat transfer in 3D gray semitransparent medium
摘要： Monte Carlo ray-tracing method (MCRTM) is widely used for solving the Radiative Transfer equation (RTE) due to its high accuracy and flexibility. In this paper, a MCRTM is developed for solving the radiative heat transfer in gray semitransparent media with complex geometries which are discretized by 3D unstructured grids. A novel algorithm associated to unstructured four-node tetrahedron element is proposed for generating random emitting positions of rays, and the ray tracing process is performed based on Beer's law. Meanwhile, radiation distribution factors are used for calculating radiative source terms which are loaded to the grid. The present method is first validated by comparing the predictive results with those from previous studies on a cubic enclosure, a 3D L-shaped enclosure, and a 3D elliptical enclosure, respectively. Furthermore, a radiation-conduction heat transfer problem is examined in a cylindrical enclosure. All the comparisons show that the present method is in good agreement with these previous cases. This method can be well adapted to various complex geometries. In addition, since the source term is calculated by the radiation distribution factor, which can be reused for different conditions as long as the volumetric radiative properties remain unchanged, this will bring great advantage when coupled with other heat transfer models such as conduction, convection, combustion, etc.
关键词： Monte Carlo ray-tracing method,Radiative heat transfer,Semitransparent medium,Radiation distribution factor,Unstructured grids
更新于2025-09-23 15:23:52
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Radiative characteristics of Voronoi open-cell foams made from semitransparent media
摘要： The radiative characterization of open-cell foams made from semitransparent solids is more complex than that made from opaque media. This study aims to understand how the component radiative properties and structural parameters of such open-cell foams affect their radiative characteristics. A radiative transfer model was established in the limit of geometric optics for the radiative characterization of a family of numerically generated Voronoi foams with open cells. It considers the reflection and refraction at the solid surface and the transmission, absorption and scattering process inside the solid phase. It is found that when the solid phase is in reality partially transparent, the opaque solid assumption will lead to inaccurate outcomes. Strongly scattering solid phase may cause much radiative energy to be rejected via reflection behavior, which will weaken the absorptive capability of the foam sheets as radiation absorbers. In addition, the radiative transfer model established was applied in three popular ceramic foams (alumina, silicon carbide and zirconia). The model shows advances in the field of analyzing and explaining the spectral radiative characteristics of ceramic foams. The present work can provide useful guidance when open-cell foams made from semitransparent media become potential candidates for thermal applications.
关键词： Voronoi tessellation,Radiative characterization,Ceramic foam,Semitransparent
更新于2025-09-23 15:23:52
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Transparent Electrodes Consisting of a Surface-Treated Buffer Layer Based on Tungsten Oxide for Semitransparent Perovskite Solar Cells and Four-Terminal Tandem Applications
摘要： For semitransparent devices with n-i-p structures, a metal oxide buffer material is commonly used to protect the organic hole transporting layer from damage due to sputtering of the transparent conducting oxide. Here, a surface treatment approach is addressed for tungsten oxide-based transparent electrodes through slight modification of the tungsten oxide surface with niobium oxide. Incorporation of this transparent electrode technique to the protective buffer layer significantly recovers the fill factor from 70.4% to 80.3%, approaching fill factor values of conventional opaque devices, which results in power conversion efficiencies over 18% for the semitransparent perovskite solar cells. Application of this approach to a four-terminal tandem configuration with a silicon bottom cell is demonstrated.
关键词： semitransparent solar cells,perovskite-silicon tandem,niobium oxide,tungsten oxide,perovskite solar cells
更新于2025-09-23 15:21:01
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Novel cathode buffer layer of Al(acac)3 enables efficient, large area and stable semi-transparent organic solar cells
摘要： Electrode buffer layer plays a more crucial in semi-transparent organic solar cells (ST-OSCs) than that of the opaque devices due to the additional requirements of the average visible transmittance (AVT) and color rendering index (CRI) besides the power conversion efficiency (PCE). Herein, we developed a novel cathode buffer layer Aluminum(III) acetylacetonate (Al(acac)3) via mild spin-coating with post low temperature heat treatment process. Studies show that Al(acac)3 film possess outstanding optical features and suitable energy level. Namely, the absorption of Al(acac)3 film with thickness of 10 nm is as low as 1% and the transmittance is high up to 95% in the visible and near infrared regions, guarantying full absorption of the photoactive layer and high CRI for ST-OSCs; and the suitable energy level ensures a smooth electron transport and collection process. By introducing Al(acac)3 film in ST-OSCs, the devices based on PM6:Y6 yield an efficiency of 12.41%, an AVT of 25.33% (from 370 nm to 740 nm) and a CRI of 94.6. Encouragingly, the large-area ST-OSC of 100 mm2 with Al(acac)3 buffer layer yields an efficiency of 11.28%. Further long-term stability of ST-OSCs show that the device with encapsulation retains its 60% of the initial PCE over 60 hours continuous illumination. The results indicate that Al(acac)3 is a promising cathode buffer layer for fabricating efficient, large area and stable semi-transparent organic solar cells.
关键词： Semitransparent organic solar cells,cathode buffer layer,stability,Aluminum(III) acetylacetonate,large-area device
更新于2025-09-23 15:21:01
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Semitransparent Perovskite Solar Cells
摘要： Solar cells are one of the most attractive and nonpolluting energy sources. In this field, hybrid and inorganic perovskite, which is a semiconductor, has been shown to function efficiently in the solar cell. One of the unique properties of perovskite allows it to become semitransparent—not just by controlling its optical properties. In this review we provide the most updated methods and techniques to make semitransparent perovskite solar cells: (i) the use of thin perovskite film; (ii) the possibility to self-assemble the perovskite on a photoanode, providing an empty transparent area while not sacrificing the light harvesting efficiency; (iii) the use of the solvent properties to form islands of perovskite using de-wetting on the surface; and (iv) the possibilities to form a transparent contact that makes the solar cell fully semitransparent. Finally, the potential and future features of semitransparent perovskite solar cells are presented.
关键词： Transparent Contact,Dewetting,Solar Cells,Perovskite,Thin Films,Semitransparent,Self-assembly
更新于2025-09-23 15:21:01
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Towards photovoltaic windows: scalable fabrication of semitransparent modules based on non-fullerene acceptors <i>via</i> laser-patterning
摘要： Semitransparent organic photovoltaics (OPV) possess unique properties that make them highly appealing for their integration into semitransparent architectonic elements such as windows or glazings. In order to provide sufficient transparency, non-opaque electrodes and thin photoactive layers are typically used, thus limiting the light-harvesting capacity. This can be partially overcome by using materials that absorb light mostly in the infrared region. On the other hand, the use of scalable techniques for the fabrication of semitransparent devices is often disregarded. In this work, we combine the blue, low-bandgap polymer PBTZT-stat-BDTT-8 with the near-infrared absorbing non-fullerene acceptor 4TICO, adapting the module fabrication to low-cost manufacturing processes that are compatible with large-scale production. Fully solution-processed semitransparent solar cells over 4.7% performance are prepared from non-chlorinated formulations, in air and using scalable techniques such as blade coating. Our prototypes of semitransparent laser-patterned OPV modules exceed 30% of transparency (measured as human perception transmittance, HPT) and yield efficiencies in the range of 4%, geometrical fill factors surpassing 90% and an active area above 1 cm2. We verify the quality of cell-to-cell interconnection and optimise the geometry of the modules with the help of local optoelectronic imaging techniques. This work highlights the relevance of non-fullerene acceptors with strong absorption in the near-infrared, as they can meet industrial and technical requirements for the upscaling and integration of high-performance semitransparent OPV modules with low production costs.
关键词： scalable fabrication,laser-patterning,non-fullerene acceptors,photovoltaic windows,semitransparent organic photovoltaics
更新于2025-09-23 15:21:01
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Highlya??Transparent and Truea??Colored Semitransparent Indoor Photovoltaic Cells
摘要： Organic photovoltaic (OPV) cells are promising indoor light energy harvesters because organic materials absorb strongly in the visible range. An indoor photovoltaic (IPV) device is an effective tool for the remote off-grid wireless charging. However, as the indoor light fluxes are much weaker than the 1-Sun condition, high-performance indoor cells should have large areas in order to generate appreciable energies. They would then appear as flat, but expansive and dark objects if deployed indoors. Their presence would then alter the indoor lighting environment and affect visual perceptions. This work addresses the lighting and perception issues of IPV cells in three ways. i) A concept is proposed such that a high-efficiency, semitransparent indoor OPV cell should possess an absorbance which is mismatched with the emission spectra of the light sources. ii) It is demonstrated that bulk heterojunction (BHJ) OPV solar cells with porphyrin donors can serve as high-transparency and high-efficiency indoor light harvesters. iii) Quantitative assessment criteria are presented for the transparency and chromaticity of an indoor semitransparent OPV cell, demonstrating that porphyrin-based P2:PC71BM semitransparent BHJ cells can achieve a power conversion efficiency (PCE) exceeding 10%, and an illuminance transparency ~65%, while preserving the color perception of the light sources.
关键词： porphyrin,indoor photovoltaics,human visual perception,semitransparent devices
更新于2025-09-23 15:21:01
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Conjugated side-chains engineering of polymer donor enabling improved efficiency for polymer solar cells
摘要： Generally, molecular optimization is widely used to fine-tune the absorption features and energy levels of photovoltaic materials to improve their photovoltaic performance for polymer solar cells (PSCs). In this work, we demonstrate an example that the morphological properties can be effectively optimized by conjugated side-chains engineering on benzo[1,2-b:4,5-b']dithiophene (BDT) unit. The polymer donors PBNT-S with alkylthio-thienyl substitution and PBNP-S with alkylthio-phenyl substitution have identical absorption spectra and energy levels, while exhibit significantly different morphological properties when blended with nonfullerene acceptor Y6. The PBNT-S:Y6 blend shows obviously over crystallinity with excessive domain sizes, while the PBNP-S:Y6 blend realizes better nanoscale phase separation. As a result, a notable power conversion efficiency (PCE) of 14.31% with a high fill factor (FF) of 0.694 is achieved in the PBNP-S:Y6-based device, while the PBNT-S:Y6-based device yields a moderate PCE of 11.10% and a relatively low FF of 0.605. Additionally, PBNP-S shows great potential in semitransparent PSCs, that the PBNP-S:Y6-based semitransparent PSC achieves an outstanding PCE of 11.86%, with an average visible transmittance of 24.3%. The results demonstrate a feasible strategy to manipulate the morphological properties of blend film via rational molecular optimization to improve the photovoltaic performance.
关键词： polymer solar cells,morphological properties,conjugated side-chains engineering,semitransparent PSCs,power conversion efficiency
更新于2025-09-23 15:21:01
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A Blue Photosensitizer Realizing Efficient and Stable Green Solar Cells via Color Tuning by the Electrolyte
摘要： Semitransparent dye-sensitized solar cells (DSCs) are appealing as aesthetically pleasing and colorful see-through photovoltaics. Green semitransparent DSCs have been presented, but the best ones rely on green zinc porphyrin photosensitizers and high volatile electrolytes. For potential outdoor applications, the zinc porphyrin DSCs employing ionic liquid electrolytes merely reached a power conversion efficiency (PCE) of 6.3% even with opaque mesoporous TiO2 films. Herein, the new green DSC is realized by using a blue organic photosensitizer in conjunction with an orange ionic-liquid-based electrolyte, presenting a simple and an effective path for color tuning of photovoltaics. The new approach allows for broadly modulating the color from spring green to cyan by tuning the contributions of the light absorption by the dye-sensitized TiO2 film and the electrolyte layer. The new semitransparent DSCs with spring green to cyan colors have PCEs ranging from 6.7% to 8.1% and show stability for 1000 h under accelerated ageing test at 80 °C, superior to the zinc porphyrin DSCs. The findings pave a new way to achieve efficient and stable colorful solar cells.
关键词： semitransparent solar cells,blue dyes,porphyrin dyes,dye-sensitized solar cells,ionic liquid electrolytes
更新于2025-09-23 15:19:57
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Dimension-controlled Growth of Antimony-based Perovskite-like Halide for Lead-free and Semitransparent Photovoltaics
摘要： Antimony (Sb) has been identified as a promising candidate for replacing toxic lead (Pb) in perovskite materials because Sb-based perovskite-like halides exhibit not only intrinsic thermodynamic stability but also a unique set of intriguing optoelectronic characteristics. However, Sb-based perovskite-like halides still suffer from a poor film morphology and uncontrollable halide constituents, which result from the disorder of the growth process. Herein, we propose a simple strategy to facilitate heterogeneous nucleation and control the dimension transformation by introducing bis(trifluoromethane)sulfonimide lithium (LiTFSI), which produces high-quality two-dimensional (2D) MA3Sb2I9-xClx films. As the spacer molecule among Sb-based pyramidal clusters, LiTFSI plays a role in forming a zero-dimensional (0D) intermediate phase and retarding crystallization. The slower dimension transformation well stabilizes the bandgap of perovskite-like films with a fixed Cl/I ratio (~7:2) and avoids random “x” values in MA3Sb2I9-xClx films prepared from the conventional method. Based on this method, Sb-based perovskite-like solar cells (PLSCs) achieve the highest recorded power conversion efficiency (PCE) of 3.34% and retain 90% of the initial PCE after being stored in ambient conditions for over 1400 h. More importantly, semitransparent Sb-based PLSCs with PCEs from 2.62% to 3.06% and average visible transparencies (AVTs) from 42% to 23% are successfully obtained, which indicates the great potential of the emerging Pb-free halide semiconductor for broad photovoltaic applications.
关键词： Perovskite-like halides,Photovoltaics,Lead-free,Antimony,Semitransparent solar cells
更新于2025-09-23 15:19:57