5,713 research outputs found
Increased cell efficiency in InGaAs thin film solar cells with dielectric and metal back reflectors
Compound single junction and multijunction solar
cells enable very high photovoltaic efficiencies by virtue of
employing different band gap materials in seriesconnected
tandem cells to access the full solar spectrum.
Researchers focused on improving the electrical properties
of solar cells by optimizing the material growth conditions,
however relatively little work to date has been devoted
to light trapping and enhanced absorption in III-V
compound solar cells using back reflectors. We studied
absorption enhancement in InGaAs and InGaAsP thin film
solar cells by means of numerical modeling. Flat dielectric
and metal back reflectors that might be introduced into the
solar cell via wafer-bonding, epitaxial lift-off or deposition
techniques have been shown to increase the short circuit
current and the photovoltaic efficiency of solar cells
Radiation hardness of Ga0.5In0.5 P/GaAs tandem solar cells
The radiation hardness of a two-junction monolithic Ga sub 0.5 In sub 0.5 P/GaAs cell with tunnel junction interconnect was investigated. Related single junction cells were also studied to identify the origins of the radiation losses. The optimal design of the cell is discussed. The air mass efficiency of an optimized tandem cell after irradiation with 10(exp 15) cm (-2) 1 MeV electrons is estimated to be 20 percent using currently available technology
III-V Solar Cells
III-V materials show a wide range of gaps making them ideal for the design of
high efficiency solar cells. This chapter reviews relevant growth methods and
material properties of these materials and discusses methods of combining
heterogeneous materials, demonstrating the flexibility of design possible with
these materials. The fundamental loss mechanisms of solar cells are analysed
and quantified as a prelude to analysing high efficiency cell designs in
single, tandem, and triple junction solar cells. The detailed analysis of loss
mechanisms is used to obtain understanding of the limiting behaviour of these
designs, and show that bulk cells remain dominated by non-radiative losses
despite unity ideality factors. To conclude, this is contrasted with the
operating regime of nanostructured solar cells which can be shown to operate in
a radiatively dominated mode, and which therefore approach ideal solar cell
efficiency limits.Comment: Draft of chapter in Materials Challenges: Inorganic Photovoltaic
Solar Energy - RSC Energy and Environment Series v. 1
Multijunction cells for concentrators: Technology prospects
Development of high-efficiency multijunction solar cells for concentrator applications is a key step in achieving the goals of the U.S. Department of Energy National Photovoltaics Program. This report summarizes findings of an issue study conducted by the Jet Propulsion Laboratory Photovoltaic Analysis and Integration Center, with the assistance of the Solar Energy Research Institute and Sandia National laboratoies, which surveyed multijunction cell research for concentrators undertaken by federal agencies and by private industry. The team evaluated the potentials of research activities sponsored by DOE and by corporate funding to achieve projected high-efficiency goals and developed summary statements regarding industry expectations. Recommendations are made for the direction of future work to address specific unresolved aspects of multijunction cell technology
Sodium hydroxide pretreatment as an effective approach to reduce the dye/holes recombination reaction in P-Type DSCs
We report the synthesis of a novel squaraine dye (VG21-C12) and investigate its behavior
as p-type sensitizer for p-type Dye-Sensitized Solar Cells. The results are compared
with O4-C12, a well-known sensitizer for p-DSC, and sodium hydroxide pretreatment
is described as an effective approach to reduce the dye/holes recombination. Various
variable investigation such as dipping time, dye loading, photocurrent, and resulting cell
efficiency are also reported. Electrochemical impedance spectroscopy (EIS) was utilized
for investigating charge transport properties of the different photoelectrodes and the
recombination phenomena that occur at the (un)modified electrode/electrolyte interface
Relaxed Current Matching Requirements in Highly Luminescent Perovskite Tandem Solar Cells and Their Fundamental Efficiency Limits.
Perovskite-based tandem solar cells are of increasing interest as they approach commercialization. Here we use experimental parameters from optical spectroscopy measurements to calculate the limiting efficiency of perovskite-silicon and all-perovskite two-terminal tandems, employing currently available bandgap materials, as 42.0% and 40.8%, respectively. We show luminescence coupling between subcells (the optical transfer of photons from the high-bandgap to low-bandgap subcell) relaxes current matching when the high-bandgap subcell is a luminescent perovskite. We calculate that luminescence coupling becomes important at charge trapping rates (â€106 s-1) already being achieved in relevant halide perovskites. Luminescence coupling increases flexibility in subcell thicknesses and tolerance to different spectral conditions. For maximal benefit, the high-bandgap subcell should have the higher short-circuit current under average spectral conditions. This can be achieved by reducing the bandgap of the high-bandgap subcell, allowing wider, unstable bandgap compositions to be avoided. Lastly, we visualize luminescence coupling in an all-perovskite tandem through cross-section luminescence imaging.ARB acknowledges funding from a Winton Studentship, Oppenheimer Studentship the Engineering and Physical Sciences Research Council (EPSRC) Doctoral Training Centre in Photovoltaics (CDT-PV). ARB thanks Luis Pazos-OutĂłn for supplying data for MAPbI3 solar cells. FL acknowledges financial support from the Alexander Von Humboldt Foundation via the Feodor Lynen program and thanks Prof. Sir R. Friend for supporting his Fellowship at the Cavendish Laboratory. Y-HC acknowledges the funding from Taiwan Cambridge Scholarship. AJ-S gratefully acknowledges a postdoctoral scholarship from the Max Planck Society. KF acknowledges a George and Lilian Schiff Studentship, Winton Studentship, the Engineering and Physical Sciences Research Council (EPSRC) studentship, Cambridge Trust Scholarship, and Robert Gardiner Scholarship. GE was funded by NRELâs LDRD program. ER acknowledges the European Research Council (ERC) under the European Unionâs Horizon 2020 research and innovation programme (HYPERION, Grant Agreement Number 756962) and the EPSRC for a DTP Part Studentship. MA-J acknowledges funding support from EPSRC through the program grant: EP/M005143/1. MA-J thanks Cambridge Materials Limited for their funding and technical support. MA acknowledges funding from the European Research Council (ERC) (grant agreement No. 756962 [HYPERION]) and the Marie SkĆodowska-Curie actions (grant agreement No. 841386) under the European Unionâs Horizon 2020 research and innovation programme. BVL acknowledges funding from the Max Planck Society, the Cluster of Excellence e-conversion and the Center for Nanoscience (CeNS). SDS acknowledges the Royal Society and Tata Group (UF150033) and the EPSRC (EP/R023980/1, EP/T02030X/1, EP/S030638/1). We thank Axel Palmstrom and William Nemeth at NREL for depositing some of the layers in the tandem stack
Relaxed Current Matching Requirements in Highly Luminescent Perovskite Tandem Solar Cells and Their Fundamental Efficiency Limits
Perovskite-based tandem solar cells are of increasing interest as they approach commercialization. Here we use experimental parameters from optical spectroscopy measurements to calculate the limiting efficiency of perovskiteâsilicon and all-perovskite two-terminal tandems, employing currently available bandgap materials, as 42.0% and 40.8%, respectively. We show luminescence coupling between subcells (the optical transfer of photons from the high-bandgap to low-bandgap subcell) relaxes current matching when the high-bandgap subcell is a luminescent perovskite. We calculate that luminescence coupling becomes important at charge trapping rates (â€106 sâ1) already being achieved in relevant halide perovskites. Luminescence coupling increases flexibility in subcell thicknesses and tolerance to different spectral conditions. For maximal benefit, the high-bandgap subcell should have the higher short-circuit current under average spectral conditions. This can be achieved by reducing the bandgap of the high-bandgap subcell, allowing wider, unstable bandgap compositions to be avoided. Lastly, we visualize luminescence coupling in an all-perovskite tandem through cross-section luminescence imaging
Optical simulations and optimization of perovskite/CI(G)S tandem solar cells using the transfer matrix method
In this work we employ the transfer matrix method for the analysis of optical materials properties to simulate and optimize monolithic tandem solar cell devices based on CuInGaSe, CI(G)S, and perovskite (PVK) absorbers. By finding models that fit well the experimental data of the CI(G)S solar cell, the semitransparent perovskite solar cell (PSC) and the PVK/CI(G)S monolithic tandem solar cell, we were able to perform a detailed optical loss analysis that allowed us to determine sources of parasitic absorption. We found better substitute materials for the transport layers to increase the power conversion efficiency and, in case of semitransparent PSCs, sub-bandgap transmittance. Our results set guidelines for the monolithic PVK/CI(G)S tandem solar cells development, predicting an achievable efficiency of 30%
Three Terminal Perovskite/Silicon Solar Cell with Bipolar Transistor Architecture
Solar photovoltaic energy is the most prominent candidate to speed up the transition from the existing non-renewable energy system to a more efficient and environmentally friendly one. Currently, silicon cells dominate the photovoltaic market owing to their cost-effectiveness and high efficiency, nowadays approaching the theoretical limit. Higher efficiency can be achieved by tandem devices, where a wide bandgap semiconductor is stacked on top of the silicon cell. Thin-film perovskite technology has emerged as one of the most promising for the development of silicon-based tandems because of the optimal perovskite opto-electronic properties and the fast progress achieved in the last decade. While most of the reported perovskite/silicon tandem devices exploit a two-terminal series connected structure, three-terminal solutions have recently drawn significant attention due to their potential for higher energy yield. In this work, we report for the first time a theoretical study, based on validated optical and electrical simulations, of three-terminal perovskite/silicon solar cells employing a hetero-junction bipolar transistor structure. With respect to other three-terminal tandems proposed so far, the transistor structure can be implemented with rear-contact silicon cells, which are simpler and more common than interdigitated back-contact ones
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