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Plasmon Ag and CdS quantum dot co-decorated 3D hierarchical ball-flower-like Bi <sub/>5</sub> O <sub/>7</sub> I nanosheets as tandem heterojunctions for enhanced photothermal–photocatalytic performance
摘要： Plasmon Ag and CdS quantum dot co-decorated three-dimensional (3D) hierarchical ball-flower-like Bi5O7I nanosheets as tandem heterojunction photocatalysts are synthesized by oil bath, photoreduction and hydrothermal processes. The formation of a tandem heterojunction structure facilitates the migration and spatial separation of photogenerated electron–hole pairs. Plasmon Ag nanoparticles can generate hot electrons to enhance the photothermal performance due to the surface plasmon resonance (SPR) effect. The unique 3D hierarchical ball-flower-like Bi5O7I nanosheets can provide a number of surface active sites and allow incident light to be reflected multiple times within the Bi5O7I nanosheets, thus improving the light utilization. Under the protection of Bi5O7I nanosheets, CdS quantum dots which are deposited by a hydrothermal strategy can effectively avoid photocorrosion. In addition, the introduction of Ag nanoparticles and CdS quantum dots extends the photoresponse to the near infrared (NIR) region. The photocatalytic degradation rate of Bi5O7I/Ag/CdS composites with a CdS content of 5.76 wt% exhibits the best photocatalytic activity, which is several times higher than that of pristine Bi5O7I. The photocatalytic hydrogen evolution is about 10 times higher than that over Bi5O7I nanosheets. Moreover, the photothermal efficiency of Bi5O7I/Ag/CdS is also improved obviously. The results of cyclic experiments show that the composite photocatalysts have high stability. The outstanding photocatalytic and photothermal performance is attributed to the formation of tandem heterojunctions favoring the separation of charge carriers, the 3D hierarchical structure of Bi5O7I offering adequate surface active sites, and the SPR effect of Ag promoting the photothermal effect. These novel Bi5O7I/Ag/CdS tandem heterojunctions may provide a new insight into the synthesis of other photocatalysts with synergistic photocatalytic–photothermal effects.
关键词： tandem heterojunctions,photothermal–photocatalytic performance,Bi5O7I nanosheets,CdS quantum dot,Plasmon Ag
更新于2025-09-16 10:30:52
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Power Losses in the Front Transparent Conductive Oxide Layer of Silicon Heterojunction Solar Cells: Design Guide for Single-Junction and Four-Terminal Tandem Applications
摘要： In silicon heterojunction solar cells, optimization of the front transparent conductive oxide (TCO) layer is required in order to minimize both electrical and optical losses. In this article, design guidelines for this overall power loss minimization are presented—extending previous TCO optimization work that was limited to the maximization of the short-circuit current density alone—and these are used to prescribe the best TCOs for both single-junction and silicon-based four-terminal tandem applications. The employed procedure determines the loss associated with the front TCO layer as a function of the TCO carrier density, mobility, and thickness, as well as the pitch between the front electrode fingers. For a representative indium tin oxide (ITO) film with a mobility of approximately 20 cm2·V?1·s?1 and a carrier density of 2.5 × 1020 cm?3, the loss over the 700–1200 nm infrared wavelength range—the spectrum reaching the silicon bottom cell in a typical tandem structure—is minimized by using a finger pitch of 3 mm and an ITO thickness of 100–110 nm. This compares with an optimal finger pitch of 2 mm and an optimal ITO thickness of 70 nm for the same cell operating as a single-junction device under full spectrum. The methodology presented can also readily be applied to TCO materials other than ITO, to a wide variety of specific four-terminal tandem architectures and, with minor modifications, to rear TCO layers.
关键词： infrared (IR) spectrum,tandem solar cells,silicon heterojunction (SHJ) solar cells,transparent conductive oxide (TCO),Four-terminal
更新于2025-09-16 10:30:52
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Enhancing electron diffusion length in narrow-bandgap perovskites for efficient monolithic perovskite tandem solar cells
摘要： Developing multijunction perovskite solar cells (PSCs) is an attractive route to boost PSC efficiencies to above the single-junction Shockley-Queisser limit. However, commonly used tin-based narrow-bandgap perovskites have shorter carrier diffusion lengths and lower absorption coefficient than lead-based perovskites, limiting the efficiency of perovskite-perovskite tandem solar cells. In this work, we discover that the charge collection efficiency in tin-based PSCs is limited by a short diffusion length of electrons. Adding 0.03 molar percent of cadmium ions into tin-perovskite precursors reduce the background free hole concentration and electron trap density, yielding a long electron diffusion length of 2.72 ± 0.15 μm. It increases the optimized thickness of narrow-bandgap perovskite films to 1000 nm, yielding exceptional stabilized efficiencies of 20.2 and 22.7% for single junction narrow-bandgap PSCs and monolithic perovskite-perovskite tandem cells, respectively. This work provides a promising method to enhance the optoelectronic properties of narrow-bandgap perovskites and unleash the potential of perovskite-perovskite tandem solar cells.
关键词： narrow-bandgap perovskites,perovskite solar cells,tandem solar cells,electron diffusion length,cadmium ions
更新于2025-09-16 10:30:52
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Sputtered Transparent Electrodes (IO:H and IZO) with Low Parasitic Near-Infrared Absorption for Perovskite-Cu(In,Ga)Se <sub/>2</sub> Tandem Solar Cells
摘要： Hybrid lead halide perovskite solar cells (PSCs) in tandem application with copper indium gallium diselenide (CIGS) solar cells represent one of the most promising all-thin-film technologies for next-generation photovoltaic devices. To minimize parasitic near-infrared (NIR) absorption losses in the electrodes, this work advances hydrogenated indium oxide (IO:H) and indium zinc oxide (IZO) electrodes for semi-transparent perovskite solar cells. The total NIR absorptance (800 nm to 1300 nm) of the perovskite top cell is reduced to <7 %, maximizing the bottom cell output current. Already taking first steps towards up-scaling, the perovskite active area is increased to match the CIGS active area of 0.5 cm2, and the RS is optimized by the implementation of a metal grid. The semitransparent perovskite solar cell reaches a power conversion efficiency of 15 %. Combined with a CIGS bottom solar cell, a 4-terminal tandem solar cell with 23 % power conversion efficiency is demonstrated. We conduct detailed current loss analyses of the complete tandem devices to monitor and evaluate the improvements of this work.
关键词： CIGS,tandem,indium oxide,TCO,current loss analysis,Perovskite
更新于2025-09-16 10:30:52
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Highly efficient flexible organic light-emitting diodes based on a high-temperature durable mica substrate
摘要： Muscovite mica is expected to show great potential in flexible optoelectronics due to its superb temperature tolerance, high transmittance, chemical stability, and mechanical durability. This flexible substrate produces sputtered transparent conducting electrodes (TCEs) with excellent film quality with high transmittance and conductivity. In this study, a designed composite TCE consisting of aluminum-doped zinc oxide (AZO) and indium tin oxide (ITO) is proposed to simultaneously maximize flexibility and conductivity. Blue-, green-, and red-emitting flexible organic light-emitting diodes (FOLEDs) using composite TCEs on mica exhibited satisfactory performance with maximum respective electroluminescence efficiencies of 18.1% (38.7 cd/A), 18.7% (66.2 cd/A), and 13.3% (22.2 cd/A). Furthermore, the green-emitting FOLEDs were modified to construct tandem FOLEDs, giving a higher peak efficiency of 27.9% (93.3 cd/A) and saturated green emission. These results can serve as a useful reference for future work on composite TCEs on mica for FOLEDs in display and lighting applications.
关键词： Organic light-emitting diodes (OLEDs),Flexible,Tandem,Indium tin oxide (ITO),Muscovite mica,Aluminum-doped zinc oxide (AZO)
更新于2025-09-16 10:30:52
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Large Area 23%-Efficient Monolithic Perovskite/Homo-Junction-Silicon Tandem Solar Cell With Enhanced UV Stability Using Down-Shifting Material
摘要： UV induced degradation and parasitic ultraviolet (UV) absorption by the 'sun-facing' carrier transport layer in a perovskite cell hinders stability and electrical performance when the perovskite cell is a top cell for a Si-based tandem. In this work, we tackle these issues by applying textured polydimethylsiloxane (PDMS) films that incorporate a down-shifting material (Ba,Sr)2SiO4:Eu2+ micron phosphor on the front of monolithic perovskite/silicon tandem cells. This film serves multiple purposes: antireflective control for the top cell, light trapping in the Si cell as well as absorbing UV and re-emitting green light with high quantum yield. When applied onto a 4 cm2 monolithic perovskite/silicon tandem solar cell, the power conversion efficiency was improved from 20.1% (baseline device without any anti-reflective film) to 22.3% (device with anti-reflective film but without the phosphors) and to 23.1% (device with down-shifting and antireflective film). The steady-state efficiency of 23.0% and a high FF of 81% achieved by the champion device are the highest values to date for a monolithic perovskite/Si tandem that uses homo-junction-silicon bottom cell. Moreover, results of continuous UV irradiation test show that this composite down-shifting antireflection film significantly enhances the UV stability for the tandem device. This work demonstrates an elegant approach for improving the efficiency and stability for larger area perovskite/silicon tandems.
关键词： perovskite/silicon tandem solar cells,down-shifting material,efficiency improvement,polydimethylsiloxane (PDMS),UV stability
更新于2025-09-16 10:30:52
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Organic tandem solar cells with 18.6% efficiency
摘要： Tandem organic photovoltaic (TOPV) cell is one of the technologies to harvest more solar power by staking two or more OPV devices on top of each other. Recently, the highest power conversion efficiency (PCE) ever achieved was 17.3%. Herein, this paper simulates the response of 676 different TOPV devices that consists front and back OPV cells. For this purpose, this paper uses the best 26 single-cell OPV devices to form the TOPV front and back cells combinations. The results show that there are some new TOPVs that can exceed 17.3% efficiency limit for TOPV. Also, in this work thickness optimization was performed for these new TOPV devices with an objective of efficiency maximization. As a result, using PBDTS-TDZ: ITIC in the front cells and PTB7-Th: O6T-4F:PC71BM in the back cell gives 18.6% efficiency. Likewise, the TOPV of PBDB-T-2F:TfIF-4FIC in the front cell with PTB7-Th:O6T-4F:PC71BM in the back cell gives 18.06% efficiency.
关键词： Organic materials,External quantum efficiency,Tandem organic solar cells,Optimization,Simulation
更新于2025-09-16 10:30:52
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Wide‐Bandgap Perovskite/Gallium Arsenide Tandem Solar Cells
摘要： Gallium arsenide (GaAs) photovoltaic (PV) cells have been widely investigated due to their merits such as thin-film feasibility, flexibility, and high efficiency. To further increase their performance, a wider bandgap PV structure such as indium gallium phosphide (InGaP) has been integrated in two-terminal (2T) tandem configuration. However, it increases the overall fabrication cost, complicated tunnel-junction diode connecting subcells are inevitable, and materials are limited by lattice matching. Here, high-efficiency and stable wide-bandgap perovskite PVs having comparable bandgap to InGaP (1.8–1.9 eV) are developed, which can be stable low-cost add-on layers to further enhance the performance of GaAs PVs as tandem configurations by showing an efficiency improvement from 21.68% to 24.27% (2T configuration) and 25.19% (4T configuration). This approach is also feasible for thin-film GaAs PV, essential to reduce its fabrication cost for commercialization, with performance increasing from 21.85% to 24.32% and superior flexibility (1000 times bending) in a tandem configuration. Additionally, potential routes to over 30% stable perovskite/GaAs tandems, comparable to InGaP/GaAs with lower cost, are considered. This work can be an initial step to reach the objective of improving the usability of GaAs PV technology with enhanced performance for applications for which lightness and flexibility are crucial, without a significant additional cost increase.
关键词： gallium arsenide,phase segregation,perovskite/GaAs tandem cells,thin-film flexible tandem cells,wide-bandgap perovskites
更新于2025-09-12 10:27:22
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Spatially and Spectrally Resolved Absorptivity: New Approach for Degradation Studies in Perovskite and Perovskite/Silicon Tandem Solar Cells
摘要： Instability in perovskite solar cells is the main challenge for the commercialization of this solar technology. Here, a contactless, nondestructive approach is reported to study degradation across perovskite and perovskite/silicon tandem solar cells. The technique employs spectrally and spatially resolved absorptivity at sub-bandgap wavelengths of perovskite materials, extracted from their luminescence spectra. Parasitic absorption in other layers, carrier diffusion, and photon smearing phenomena are all demonstrated to have negligible effects on the extracted absorptivity. The absorptivity is demonstrated to reflect real degradation in the perovskite film and is much more robust and sensitive than its luminescence spectral peak position, representing its optical bandgap, and intensity. The technique is applied to study various common factors which induce and accelerate degradation in perovskite solar cells including air and heat exposure and light soaking. Finally, the technique is employed to extract the individual absorptivity component from the perovskite layer in a monolithic perovskite/silicon tandem structure. The results demonstrate the value of this approach for monitoring degradation mechanisms in perovskite and perovskite/silicon tandem cells at early stages of degradation and various fabrication stages.
关键词： tandem,absorptivity,photoluminescence,perovskite,degradation
更新于2025-09-12 10:27:22
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Co(OH)2/BiVO4 photoanode in tandem with a carbon-based perovskite solar cell for solar-driven overall water splitting
摘要： BiVO4 as a promising candidate photoanode material for PEC water splitting has been paid much attention due to its low cost, nontoxicity, high stability and narrow band gap energy of 2.4 eV. However, owing to its short carrier diffusion length and poor charge separation consequence the achieved efficiency of the BiVO4 photoanode is still limited. Herein, we addressed this issue by loading Co(OH)2 onto as-prepared BiVO4 to fabricate Co(OH)2/BiVO4 heterojunction photoanode via a simple solution impregnation method, in which Co(OH)2 as a modifier can increase interface charge separation efficiency from 44% of BiVO4 to 92% of Co(OH)2/BiVO4. As a result, the water-splitting photocurrent density was significantly enhanced from 1.57 mA/cm2 of BiVO4 to 4.52 mA/cm2 of Co(OH)2/BiVO4 at 1.23 V vs. RHE under 1-sun illumination. Further, the Co(OH)2/BiVO4 photoanode was assembled in tandem with a single sealed carbon-based PSC, and the resulting PV-PEC device showed a high STH efficiency of 4.6% and decent stability. The produced H2 and O2 gases were determined as ~68 μmol/cm2/h and ~34 μmol/cm2/h, respectively, corresponding to the 2:1 ratio of water splitting reaction with a faradaic efficiency of ~98%.
关键词： heterojunction photoanode,water splitting,tandem device,Co(OH)2/BiVO4
更新于2025-09-12 10:27:22