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Computational study of stack/terminal topologies for perovskite based bifacial tandem solar cells
摘要： With the rapid progress on perovskite (PVK) and bifacial solar cells, there is a huge interest in integrating PVK with established technologies such as crystalline silicon (c-Si) and CIGS for bifacial tandem structures. Here we use self-consistent optical/electrical simulations to compare various stack/terminal configurations for bifacial tandem solar cells having PVK as the top cell. In particular, we compare a non-conventional three-terminal four-junction (3T-4J) twin bifacial tandem configuration with standard two-junction bifacial tandem structures having a monolithic two-terminal (2T-2J) or mechanically stacked four-terminal (4T-2J) integration. We show that the optimal design of 2T-2J cell is strongly albedo dependent – the cell designed for a given albedo will perform sub-optimally for other albedo due to the current-matching constraint. A mechanically stacked 4T-2J cell, on the other hand, can perform optimally for a broad range of albedo, albeit at the cost of additional processing complications. The 3T-4J twin tandem cell could offer a relatively simpler process through back-to-back bonding of two identical monolithic 2J tandem cells with superior utilization of albedo in a broad range. The potential benefit of 3T-4J cell could however be limited due to a high front reflection, hence necessitating anti-reflection approaches. We further quantify the effect of bottom subcell material on the efficiency for PVK tandem cells. Using state-of-the-art bottom subcells, efficiency of 33% and 30% respectively could be achieved at the average Earth albedo of 30%. By integrating advanced anti-reflectance techniques, the absolute cell efficiency could further be improved by 4%.
关键词： Albedo,Simulations,Current-matching,Tandem,Bifacial gain
更新于2025-09-23 15:21:01
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Performance of hybrid energy devices consisting of photovoltaic cells and thermoelectric generators
摘要： The aim of our study on hybrid energy devices (HEDs) is to find out the prerequisites for enhancing the performance of the HEDs using solar energy. In this work, first of all, the performance of the HEDs composed of photovoltaic cells (PVCs) and thermoelectric generators (TEGs) is analyzed, and then the contribution of three different interfaces between the PVC and TEG components to HED performance is assessed under solar irradiance from 200 to 1000 W/m2. The significant result of the analysis emphasizes that the performance of HEDs is enhanced when short-circuit current in HEDs is comparable with the PVCs and the thermoelectric voltage generated by the TEG is large. Furthermore, interfaces with high solar-energy-absorption efficiencies and high thermal conductivity cause TEGs to generate large thermoelectric voltages. Thus, the design of the interfaces plays an important role in enhancing HED performance.
关键词： Hybrid energy device,Photovoltaic,Thermoelectric,Interface layer,Current matching
更新于2025-09-19 17:13:59
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Light Management in Monolithic Perovskite/Silicon Tandem Solar Cells
摘要： Perovskite/silicon tandem solar cells (TSCs), especially 2-terminal, with record efficiency of 28% already been realized, have presented great potentials to be low-cost and efficient substitutes for dominant silicon photovoltaics. It is quite realistic to achieve efficiencies exceeding 30%, which have been indicated by extensive optical simulations. Super light management in monolithic perovskite/silicon TSCs is one of the prerequisites to make it a reality. In this review, various forms of optical losses, such as reflection loss, parasitic absorption and current mismatch, are analyzed systematically to provide better understanding of the performance of perovskite/silicon TSCs. Particularly, a simple refractive index matching rule derived from the Fresnel equation is proposed as a basis of material selection and device design. Meanwhile, an overview of current strategies and challenges in monolithic perovskite/silicon TSCs is highlighted, comprising of bandgap engineering of perovskites and light trapping methods, aiming to provide guidance for further improvement of the tandem devices.
关键词： anti-reflection,light management,parasitic absorption,light trapping,current matching,monolithic perovskite/silicon tandem solar cells
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 62nd International Midwest Symposium on Circuits and Systems (MWSCAS) - Dallas, TX, USA (2019.8.4-2019.8.7)] 2019 IEEE 62nd International Midwest Symposium on Circuits and Systems (MWSCAS) - Multi-Channel LED Driver with Accurate Current Matching for Portable Applications
摘要： In this paper, we present a multi-string LED driver based on a current-limiting hysteretic boost converter, which is capable of driving ten LEDs in five parallel strings. An accurate current matching circuit with low voltage headroom requirement is implemented to match currents in all LED strings. Dynamic compensation of the LED forward voltage mismatch between the strings is achieved with the introduction of a minimum voltage selector block. A PFM dimming circuit is designed to operate with a 200 kHz clock and has 11 programmable dimming ratios, ranging from 2:1 to 2048:1. This LED driver is implemented in 0.6-μm CMOS process and operates from a Li-ion battery with a voltage range 3 – 4.2 V. It is suitable for backlight LED displays in mobile devices.
关键词： dimming,hysteretic controller,DCM,current matching,LED driver,forward voltage mismatch
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