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Modified solar cell module uses high transmission glass and adhesives, and heat dissipation to boost power per unit area by 25% (9.84% efficiency based on cell area at 60 C and 100 mW/sq cm flux). Design is suited for automatic production and is potentially more cost effective.
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Abstract Semi‐transparent perovskite solar cells (ST‐PeSCs) have tremendous potential as solar windows owing to their higher efficiency and visible transmittance. However, studies toward this application are still nascent, particularly in unraveling the interplay between how the perovskite composition impacts the achievable device performance and stability. Here, the role of A‐ and X‐site modification in APbX 3 perovskites is studied to understand their influence on these factors. Through detailed experimental and simulation work, it is found that a perovskite composition consisting of cesium (Cs) and formamidinium (FA) at the A‐site delivers the best device performance over a range of band gaps, which are tuned by changes to the X‐site anion. Using this optimized perovskite composition, power conversion efficiencies of 15.5% and 4.1% are achieved for ST‐PeSCs with average visible transmittance values between 20.7% and 52.4%, respectively. Furthermore, the CsFA‐based ST‐PeSCs show excellent long‐term stability under continuous illumination and heating. The stability of the precursor solutions across each of the studied compositions has also been considered, showing dramatic differences in the structural properties of the perovskites and their device performance for all mixed A‐site compositions possessing the archetypal methyl ammonium species, while also confirming the superior stability of the CsFA precursor solutions.
Transparent conductive oxides are used in many technologies and it is important to understand their interfacial chemical reactions. Here, we use recently developed thermomechanical cleaving and X-ray photoelectron spectroscopy to probe oxidation states at the SnO 2 interface of CdTe solar cells. We show that tin oxide promotes the formation of nanometer-scale oxides of tellurium and sulfur, largely during CdCl 2 /O 2 activation. Surprisingly, in copper-doped devices, relatively low temperature anneals (180-260 degrees C) to diffuse and activate copper acceptors also cause significant oxidation changes at the front interface, providing a heretofore missing aspect of how back contact processes can modify device transport, recombination, and performance. For Group V-doped devices, this same oxidation process causes segregation of the dopants to the SnO 2 interface in their oxidized states, implying that adjacent regions in the absorber have been depleted of dopants. Intriguingly, we demonstrate that because of their layered, van der Walls-bonded crystal structure, spatially segregated Group V oxides may represent a mechanically weak layer in a finished device.
This project seeks to develop device design, materials composition, and processing tools and parameters to fabricate semi-transparent perovskite solar cells and modules for application in stand-alone products or added to other solar cells in a mechanically stacked tandem configuration. This technology presents significant advanced manufacturing challenges and opportunities in getting to scale, including development of perovskite inks, scalable perovskite and heterojunction deposition and annealing processes, heterojunction composition, transparent electrode composition and deposition process, anti-reflection layer composition and deposition process, and cell to module integration processes. Modification 5: The proposed project seeks to develop device design, materials composition, and processing tools and parameters to fabricate semi-transparent perovskite solar cells and modules for application in stand-alone products or added to other solar cells in a mechanically-stacked tandem configuration. This technology presents significant advanced manufacturing challenges and opportunities in getting to scale, including development of perovskite inks, scalable perovskite and heterojunction deposition and annealing processes, heterojunction composition, transparent electrode composition and deposition process, passivation layers including in module scribes, anti-reflection layer composition and deposition process, and cell to module integration processes. Advanced metrology and characterization will be performed on perovskite films, cells and module. Furthermore, we will examine module or materials recycling for circular economy considerations. Modifcation 6: Gigahertz frequency microwave pump-probe spectroscopies are highly sensitive to thin film semiconductor photoconductivity of individual and stacks of layers that comprise perovskite solar cells. As such, these techniques will be used to qualify reproducibility and quality correlations during the manufacturing process. Modification 7: Mechanical adhesion of top contacts within perovskite modules significantly impacts the durability of the module when exposed to accelerated degradation testing. The adhesion between the perovskite/transport layer interface and the transport layer/top contact interface are both very sensitive small changes in processing. ALD processing conditions of the transport layer will be tuned to optimize the mechanical adhesion within the perovskite module stack.
Development of a three solar cell stack can lead to practical efficiencies greater than 30 percent (1x,AM0). A theoretical efficiency limitation of 43.7 percent at AM0 and one sun is predicted by this model. Including expected losses, a practical system efficiency of 36.8 percent is anticipated. These calculations are based on a 1.93eV/1.43eV/0.89eV energy band gap combination. AlGaAs/GaAs/GaInAsP materials can be used with a six-terminal wiring configuration. The key issues for multijunction solar cells are the top and middle solar cell performance and the sub-bandgap transparency. AstroPower has developed a technique to fabricate AlGaAs solar cells on rugged, self-supporting, transparent AlGaAs substrates. Top solar cell efficiencies greater than 11 percent AM0 have been achieved. State-of-the-art GaAs or InP devices will be used for the middle solar cell. GaInAsP will be used to fabricate the bottom solar cell. This material is lattice-matched to InP and offers a wide range of bandgaps for optimization of the three solar cell stack. Liquid phase epitaxy is being used to grow the quaternary material. Initial solar cells have shown open-circuit voltages of 462 mV for a bandgap of 0.92eV. Design rules for the multijunction three solar cell stack are discussed. The progress in the development of the self-supporting AlGaAs top solar cell and the GaInAsP bottom solar cell is presented.
Abstract Following the 2nd release of the “Emerging PV reports,” the best achievements in the performance of emerging photovoltaic devices in diverse emerging photovoltaic research subjects are summarized, as reported in peer‐reviewed articles in academic journals since August 2021. Updated graphs, tables, and analyses are provided with several performance parameters, e.g., power conversion efficiency, open‐circuit voltage, short‐circuit current density, fill factor, light utilization efficiency, and stability test energy yield. These parameters are presented as a function of the photovoltaic bandgap energy and the average visible transmittance for each technology and application, and are put into perspective using, e.g., the detailed balance efficiency limit. The 3rd installment of the “Emerging PV reports” extends the scope toward triple junction solar cells.
The design, development, fabrication, and testing of the transparent solar cell module were examined. Cell performance and material process characteristics were determined by extensive tests and design modifications were made prior to preproduction fabrication. These tests included three cell submodules and two full size engineering modules. Along with hardware and test activity, engineering documentation was prepared and submitted.
This final technical report summarizes the findings of the University of Hawaiʻi and the National Renewable Energy Laboratory on the encapsulation of perovskite solar cells using novel polymers to enable extended operational lifetimes.
A transparent conductive adhesive (TCA) interlayer for mechanically stacked multijunction solar cells provides adhesive strength and electrical connection between sub-cells when stacked. The fabrication of TCA sheets from an ethyl-vinyl acetate (EVA) matrix and silver coated compliant conductive microspheres, similar to industry-standard EVA encapsulant sheets, compatible with a standard lamination process was developed. Blade coating TCA sheets using 3D printed blades and testing of vertical conduction through the interlayer with a TCA conductivity jig allowed for reproducible measurements and low-cost fabrication. The supplemental information provides design files to enable other researchers to produce their own blades and testing jigs. We identified 0.5 mm as an optimal blade height for producing lab-scale TCA sheets and 120 °C at 3 psi for 10 min as the optimal vacuum lamination process to minimize resistance and possible damage to samples. For TCA sheets with coverages between 0.75% and 9%, the series resistance was approximately 0.2 O cm2 which should result in minimal losses for one-sun photovoltaic applications.
According to an aspect of an embodiment of the present disclosure, there is provided a solar cell panel and a method for manufacturing the same. The solar cell panel comprises: a solar cell for generating electric power from sunlight; a coverglass for covering the solar cell; transparent shims, which are disposed between the solar cell and the coverglass at the points where the distance between the solar cell and the coverglass needs to be controlled, and form a space between the solar cell and the coverglass; and adhesive layer, which fills the space between the solar cell and the coverglass and has the thickness the same as that of the transparent shims.
Abstract Flexible optoelectronics, based on non-planar substrates, hold promise for diverse applications such as wearables, health monitors, and displays due to their cost-effective manufacturing methods. Despite the superior properties of metal oxides, the challenge of processing them at high temperatures incompatible with plastic substrates necessitates innovative annealing approaches. Photonic curing, which delivers microsecond to millisecond broadband (200–1500 nm) light pulses on a sample, emerges as a viable solution. Depending on the optical properties, the targeted film absorbs the radiant energy resulting in rapid heating while the transparent substrate absorbs a minimal amount of light and remains at ambient temperature. The light intensity can be high, but since the light pulse is short, the total energy absorbed by the sample remains low and will not damage the plastic substrate. This perspective explores the innovative application of photonic curing to fabricate flexible metal oxide optoelectronics, including thin-film transistors, metal–insulator–metal devices, solar cells, transparent conductors, and Li batteries, emphasizing the conversion of sol–gel precursors to metal oxides. However, this technique was initially developed for sintering metal nanoparticles to conductive patterns and poses intriguing challenges in explaining its mechanism for metal oxide conversion, especially considering the limited absorption of visible light by most sol–gel precursors. The review delves into UV-induced photochemistry, common flexible metal-oxide optoelectronic components, and non-intuitive distinctions between photonic curing and thermal annealing. By elucidating the distinctive role of photonic curing in overcoming temperature-related challenges and advancing the fabrication of flexible metal oxide optoelectronics, this perspective offers valuable insights that could shape the future of flexible optoelectronics.
Optically transparent p-type materials play a critical role in transparent electronics including photovoltaic (PV) devices. P-type sulfide materials offer an alternative to oxides for PV application due to improved hole transport properties. Here, we report the solution-based synthesis of earth-abundant p-type transparent conducting barium copper sulfide (α-BaCu 4 S 3 , BCS) thin films. These films were characterized using scanning electron microscopy, X-ray diffraction, UV–Vis–NIR spectrophotometry, Raman spectroscopy, and spectroscopic ellipsometry. BCS films of ~100 nm thickness transmit >70% of visible light. We report on tests of the hole transport properties of these BCS films for cadmium telluride (CdTe) photovoltaics, finding that the BCS deposition process forms a beneficial tellurium (Te) rich surface on CdTe by selectively removing Cd from the surface. Based on our study, the BCS interface layer plays dual functions for CdTe PV devices as a hole transport material and as an etchant, enhancing the resulting device performance. We observed a significant increase in open-circuit voltage of CdTe solar cells with the BCS buffer layer. Furthermore, we discuss semitransparent CdTe solar cells with BCS as a hole transport layer and indium tin oxide as a finishing electrode. Semitransparent CdTe solar cells shows 13.3% conversion efficiency for the front side illumination and 1.2% efficiency for back side illumination, indicating high recombination of charge carriers generated close to the rear CdTe/BCS/ITO contact.
Thin, transparent layers comprising mats of carbon nanotubes have been proposed for providing lateral (that is, inplane) electrical conductivities for collecting electric currents from the front surfaces of the emitter layers of thin-film solar photovoltaic cells. Traditionally, thin, semitransparent films of other electrically conductive materials (usually, indium tin oxide, zinc oxide, or cadmium sulfide) have been used for this purpose. As in the cases of the traditional semitransparent conductive films, the currents collected by the nanotube layers would, in turn, be further collected by front metal contact stripes. Depending on details of a specific solar-cell design, the layer of carbon nanotubes would be deposited in addition to, or instead of, a semitransparent layer of one of these traditional conductive materials (see figure). The proposal is expected to afford the following advantages: The electrical conductivity of the carbon- nanotube layer would exceed that of the corresponding semitransparent layer of traditional electrically conductive material. The greater electrical conductivity of the carbon-nanotube layer would make it possible to retain adequate lateral electrical conductivity while reducing the thickness of, or eliminating entirely, the traditional semitransparent conductive layer. As a consequence of thinning or elimination of the traditional semitransparent conductive layer, less light would be absorbed, so that more of the incident light would be available for photovoltaic conversion. The greater electrical conductivity of the carbon-nanotube layer would make it possible to increase the distance between front metal contact stripes, in addition to (or instead of) thinning or eliminating the layer of traditional semitransparent conductive material. Consequently, the fraction of solar-cell area shadowed by front metal contact stripes would be reduced again, making more of the incident light available for photovoltaic conversion. The electrical conductivities of individual carbon nanotubes can be so high that the mat of carbon nanotubes could be made sparse enough to be adequately transparent while affording adequate lateral electrical conductivity of the mat as a whole. The thickness of the nanotube layer would be chosen so that the layer would contribute significant lateral electrical conductivity, yet would be as nearly transparent as possible to incident light. A typical thickness for satisfying these competing requirements is expected to lie between 50 and 100 nm. The optimum thickness must be calculated by comparing the lateral electrical conductivity, the distance between front metal stripes, and the amount of light lost by absorption in the nanotube layer.
The author regrets the following errors in typesetting the equations, which affected the paper's text, but did not affect any calculations, figures or conclusions.
Following the 1st release of the "Emerging photovoltaic (PV) reports", the best achievements in the performance of emerging photovoltaic devices in diverse emerging photovoltaic research subjects are summarized, as reported in peer-reviewed articles in academic journals since August 2020. Updated graphs, tables, and analyses are provided with several performance parameters, e.g., power conversion efficiency, open-circuit voltage, short-circuit current density, fill factor, light utilization efficiency, and stability test energy yield. These parameters are presented as a function of the photovoltaic bandgap energy and the average visible transmittance for each technology and application and are put into perspective using, e.g., the detailed balance efficiency limit. The 2nd installment of the "Emerging PV reports" extends the scope toward tandem solar cells and presents the current state-of-the-art in tandem solar cell performance for various material combinations.
The fundamentals of using cracked film lithography (CFL) to fabricate metal grids for transparent contacts in solar cells were studied. The underlying physics of drying-induced cracks were well-predicted by an empirical correlation relating crack spacing to capillary pressure. CFL is primarily controlled by varying the crack template thickness, which establishes a three-way tradeoff between the areal density of cracks, crack width, and spacing between cracks, which in turn determine final grid transmittance, grid sheet resistance, and the semiconductor resistance for a given solar cell. Since CFL uses a lift-off process, an additional constraint is that the metal thickness must be less than 1/3 of the crack template thickness. Furthermore, the transmittance/grid sheet resistance/wire spacing tradeoffs measured in this work were used to calculate solar cell performance: CFL-patterned grids should outperform screen-printed grids for narrow cells (0.5–2 cm wide) and/or cells with high semiconductor sheet resistance (=100 O/sq), making CFL attractive for monolithically integrated thin-film photovoltaic modules.
The paper presents an analytical treatment of transparent-emitter devices, particularly solar cells, that is more complete than previously available treatments. The proposed approach includes the effects of bandgap narrowing, Fermi-Dirac statistics, built-in field due to impurity profile, and a finite surface recombination velocity at the emitter surface. It is demonstrated that the transparent-emitter model can predict experimental values of Voc observed on n(plus)-p thin diffused junction silicon solar cells made on low-resistivity (0.1 ohm-cm) substrates. A test is included for the self-consistent validity of the transparent-emitter model. This test compares the calculated transit time of minority carriers across the emitter with the Auger-impact minority-carrier lifetime within the emitter region.