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TaS <sub/>2</sub> Back Contact Improving Oxide-Converted Cu <sub/>2</sub> BaSnS <sub/>4</sub> Solar Cells
摘要： Solar cells based on the wide band-gap Cu2BaSnS4 (CBTS) photoabsorber have achieved open circuit voltages up to 1.1 V over a short development period, making CBTS an attractive material for tandem photovoltaic and photoelectrochemical cells. In this work, we explore an alternative CBTS growth route based on oxide precursors, and we propose TaS2 as an alternative back contact material to the commonly used Mo/MoS2. The oxide precursor route does not require higher sulfurization temperatures than other more common fabrication routes, and it yields CBTS films with negligible Stokes shift between photoluminescence maximum and band gap energy, while at the same time avoiding sulfur contamination of vacuum systems. The high work-function metallic TaS2 compound is selected as a prospective hole-selective contact, which could also prevent the losses associated with carrier transport across the semiconducting MoS2 layer. By comparing CBTS solar cells with Mo and TaS2 back contacts, the latter shows a significantly lower series resistance, resulting in a 10% relative efficiency improvement. Finally, we fabricate a proof-of-concept monolithic CBTS/Si tandem cell using a thin Ti(O,N) interlayer intended both as a diffusion barrier and as a recombination layer between the two subcells.
关键词： wide band gap absorber,back contact,kesterite,cation substitution,tandem solar cell,silicon,TaS2,sputtering
更新于2025-09-12 10:27:22
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Computational Modelling of Monolithically Stacked Perovskite/Silicon Tandem Solar Cells Using Monofacial and Bifacial Designs
摘要： As the efficiency of conventional silicon (Si) solar cell is reaching closer to its thermodynamic limit, its tandem integration with emerging perovskite (PVK) solar cell is being widely explored. In this work, we use self-consistent optical and electrical simulations to computationally explore monolithically stacked 2-terminal (2-T), 2-junction (2-J) PVK/Si tandem solar cell. The optical model is based on Lambert-Beer Law while electrical model is based on drift-diffusion approach. The tandem solar cell is explored for both monofacial and bifacial configurations. The simulations show that the cell design for optimal operations is highly dependent on perovskite thickness and albedo. Under optimal design, the bifacial PVK/Si tandem cell exhibits ?? ≈ 33% for average earth albedo of 30%. Moreover, the cell exhibits a remarkable temperature coefficient of ~ ? 0.27%. Moreover, our simulation results are in good agreement with both experimental and highly intensive optical model based simulation data. With our computationally inexpensive optical model, the optimal cell design for different tandem structures can be explored in a much easier way.
关键词： monolithic,perovskite,Albedo,bifacial,current-matching,optical model,tandem
更新于2025-09-12 10:27:22
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Performance Study of the Micromorph Silicon Tandem Solar Cell Using Silvaco TCAD Simulator
摘要： This paper is concerned with the numerical modelling of a micromorph silicon tandem solar cell (a-Si:H/μc-Si:H), under series (two-terminal: 2T) and independent (four-terminal: 4T) electrical connection. The study is performed using the simulation software Silvaco TCAD. Both the initial (un-degraded or annealed) state, and the light induced degradation one (well-known Staebler–Wronski effect in a-Si:H) are considered for the studied solar cell, operating under the standard global solar spectrum (AM1.5G). The 2T- and 4T-device optimization is carried out under the effects of the intrinsic (i)-layer thickness of the two sub-cells, and the free carrier mobilities through these layers. By increasing the i-layer thickness of the two sub-cells, the 2T-micromorph tandem cell reveals an optimal conversion efficiency ?? of 10% and 7.77% corresponding, respectively, to the initial and degraded states. The 4T-configuration exhibits a relatively better ?? of 10.94% at initial state, reduced only to 9.59% at the degraded one. Further improvement of the 2T and 4T-cell output parameters is obtained by increasing the free carrier mobilities, particularly through the top-cell i-layer. By this way, the better ?? is also ensured by the 4T-device, which displays an initial state-?? of 12.31%, reduced only to 11.43% at the degraded state. However, the improved efficiencies reached by the 2T-configuration are 11.87% and 10.41% corresponding, respectively, to the initial and degraded states.
关键词： Numerical simulation,Micromorph,Tandem solar cell,μc-Si:H,a-Si:H
更新于2025-09-11 14:15:04
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Photo-driven water splitting photoelectrochemical cells by tandem organic dye sensitized solar cells with I?/I3? as redox mediator
摘要： Dye-sensitized photoelectrochemical tandem cells have shown the promise for light driven hydrogen production from water owing to the low cost, wide absorption spectra in the visible region and ease to process of their constitutive photoelectrode materials. However, most photo-driven water splitting photoelectrochemical cells driven by organic dye sensitized solar cells exhibit unsatisfactory hydrogen evolution rate, primarily attributed to their poor light capturing ability and low photocurrent performance. Here we present the construction of a tandem system consisting of an organic blue-colored S5 sensitizer-based dye-sensitized photoelectrochemical cell (DSPEC) wired in series with three spectral-complemental dyes BTA-2, APP-3 and APP-1 sensitizers-based dye-sensitized solar cell (DSC), respectively. The two spectral-complemental chromophores were used in DSC and DSPEC to ensure that the full solar spectrum could be absorbed as much as possible. The results showed that the photocurrent of tandem device was closely related to the open-circuit voltage (Voc) of sensitized DSC, in which the tandem configuration consisting of S5 based DSPEC and BTA-2 based DSC gave the best photocurrent. On this basis, tandem device with the only light energy and no external applied electrical bias was further constructed of BTA-2 based 2-junction DSC and S5 based DSPEC and obtained a photocurrent of 500 μA cm?2 for hydrogen generation. Furthermore, I?/I3 ? was used as a redox couple between dye regeneration and O2 production on the surface of Pt-IrO2/WO3. The strategy opens up the application of pure organic dyes in DSC/DSPEC tandem device.
关键词： dye-sensitized photoelectrochemical cells,water splitting,tandem device,dye-sensitized solar cells
更新于2025-09-11 14:15:04
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Enhancing PbS Colloidal Quantum Dot Tandem Solar Cell Performance by Graded Band Alignment
摘要： Colloidal quantum dot solids are attractive candidates for tandem solar cells because of their widely tunable bandgaps. However, the development of quantum dot tandem solar cell has lagged far behind that of its single-junction counterpart. One of the fundamental problems with colloidal quantum dot solar cells is the relatively small diffusion length, which limits the quantum dot absorbing layer thickness and hence the power conversion efficiency. In this research, guided by optical modelling and utilising a graded band alignment strategy, a two-terminal monolithic solution-processed quantum dot tandem solar cell has been successfully fabricated and a power conversion efficiency of 6.8% has been achieved. The band grading approach utilised the complementary tuning of work functions and band alignment through judicious choices of the nanoparticle surface chemistry and quantum dot confined size. This work demonstrates a general approach to improving the efficiency for tandem thin film solar cells.
关键词： tandem solar cells,optical modelling,Colloidal quantum dot solids,graded band alignment,power conversion efficiency
更新于2025-09-11 14:15:04
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AIP Conference Proceedings [AIP Publishing 15th International Conference on Concentrator Photovoltaic Systems (CPV-15) - Fes, Morocco (25–27 March 2019)] 15th International Conference on Concentrator Photovoltaic Systems (CPV-15) - Electrical and optical analysis of a spray coated transparent conductive adhesive for two-terminal silicon based tandem solar cells
摘要： This work presents the results of the electrical and optical characterization of a new transparent conductive adhesive (TCA) that combines the techniques of spray pyrolysis and a sol-gel like process. This approach is of particular interest since the adhesive itself forms both the electrical and the mechanical interconnection of the bonded sub-cells. The electrical and optical characterization of the developed TCA shows a minimum connecting resistivity of 17 ?cm2 and a simulated reflection at the Si-TCA interface of ≈ 20%. By coating both substrate surfaces with a TiO2 anti reflection coating (ARC), the reflectance at the Si-TCA interface was successfully reduced down to <5%. The efficiency potential of a glued dual junction device was simulated in dependence of the electrical and optical properties of the TCA. The reported values of 17 ?cm2 connecting resistivity and 20% reflection limit the device efficiency to 22.3% (71% of the maximum achievable efficiency). Reducing the reflection to below 5%, as practically demonstrated in this paper, allows to increase this value to 25.3% (>80% of maximum), while additionally reducing the connecting resistivity to 10 ?cm2 or 1 ?cm2 allows for a further increase to 27.3% and 30.0%, respectively.
关键词： reflection losses,sol-gel process,tandem solar cells,connecting resistivity,TiO2 anti reflection coating,electrical characterization,transparent conductive adhesive,optical characterization,spray pyrolysis
更新于2025-09-11 14:15:04
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The Value of Efficiency in Photovoltaics
摘要： Here, we introduce the value of efficiency (VOE), a metric that determines the maximum allowable cost for an innovation to improve the levelized cost of electricity. We use this metric to analyze historic, regional, and technological trends. We find indications for a stronger regional and sectoral market diversification. One example is tandem solar cells that could help to reduce electricity costs in US residential installations. We highlight the need for new PV technologies, like perovskites, to match leading technology degradation rates.
关键词： perovskites,value of efficiency,degradation rates,tandem solar cells,photovoltaics
更新于2025-09-11 14:15:04
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Photonic enhancement of parallel homo-tandem solar cells through the central electrode
摘要： Improvement of solar cell performance through the parallel homo-tandem architecture is studied. The cell geometry is optically designed to maximize absorption of the AM1.5 spectrum. We consider both ITO electrode and a recently devised ITO-free alternative, the Two-Resonance Tapping Cavity. The optimal geometry strongly depends on this choice. We identify two mechanisms by which tandem cells outperform single cells: (i) back-up absorption and (ii) interferometric gain mediated by the central metallic electrode. We numerically demonstrate large improvement in short-circuit current for a wide choice of realistic materials: PTB7-th:PC71BM, P3HT:PC61BM, DBP:C70, and methylammonium lead halide perovskite, as well as a theoretical material with a Shockley-Queiser type of spectral absorption plus an Urbach tail. Such an idealized response is found to reliably model real materials. A general response pattern is found that fits all the cases covered in our study, and which can serve as a guide to optimize homo-tandem cells.
关键词： Homo-tandem solar cells,ITO,TRTC,Photon management,Micro-cavity
更新于2025-09-11 14:15:04
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[IEEE 2018 International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD) - Hong Kong, China (2018.11.5-2018.11.9)] 2018 International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD) - Perovskite solar cell efficiency improvements: new device simulation
摘要： Trihalide perovskite photovoltaic (PV) solar cells have a promise to be connected into tandems with inorganic PV systems. In this paper we present p-i-n GaAs & PV cells in either in-series way or parallel connection. Comparisons made for two types of tandems by a non-monolithic connection of two experimental sub-cells and results are being discussed based on simulation analysis. It is shown that parallel connection is always more preferable when the subcells photocurrent is not balanced Total efficiency over 20 % is demonstrated for GaAs shadding effect of by MAPbI3 film, with achieved Jsc 41 mA/cm2 and high Voc, cell has better FF.
关键词： simulation,perovskite photovoltaic solar cell,tandem structure
更新于2025-09-11 14:15:04
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[IEEE 2019 IEEE Photonics Conference (IPC) - San Antonio, TX, USA (2019.9.29-2019.10.3)] 2019 IEEE Photonics Conference (IPC) - An Efficient 4-kW Level Random Fiber Laser Based on Tandem-Pumping Scheme
摘要： In this paper, we presented a monolithic high power random fiber laser with a tandem-pumping scheme. The random fiber laser seed centered at 1064 nm was pumped by a 1018 nm fiber laser and reached an output power of 8.66 W. After the two amplifiers, the seed was amplified to 4020 W and the 3 dB width of laser spectrum was broadened from 0.78 nm to 0.99 nm. To increase the efficiency of the 4 kW laser, a specially designed high absorption coefficient (0.6 dB/m @ 1018nm) 30/250 μm Yb doped fiber and high brightness 1018 nm pump laser were adopted. The optical-to-optical efficiency could reach as high as 88.5%. No obvious mode instability was found during the experiment. Furthermore, with the same amplifier stage, we have also built another 4 kW level fiber laser seeded by an oscillator consisting of a pair of fiber Bragg gratings. The comparison of the experimental results showed that high power laser based on RFL seed would have a better control on spectral broadening.
关键词： High power,tandem-pumping,random fiber laser
更新于2025-09-11 14:15:04