Chemical Passivation for Reduced Recombination Loss in Solar Cells

A perovskite solar cell with improved electron transfer efficiency and stability, comprising a perovskite layer, a composite passivation layer formed by cross-linking a polydopamine-modified layered double metal hydroxide, and a bimetallic composite oxide layer prepared by calcining a layered double metal hydroxide. The composite passivation layer is formed by coating a composite material solution onto the perovskite layer and annealing, while the bimetallic composite oxide layer is prepared by calcining a layered double metal hydroxide at 250°C for 2 hours.

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A solar cell with improved efficiency and stability, comprising a perovskite light absorption layer and a pair of transport layers, with an interface passivation material distributed in one or more of the transport layers. The passivation material contains functional groups with active hydrogen that interact with electronegative groups in adjacent layers, forming hydrogen bonds and improving carrier transport. The material can also be used as a separate passivation layer between the transport layers and perovskite layer.

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A hybrid heterojunction solar cell with improved surface passivation and reduced light absorption in non-metallic areas. The cell features a tunneling layer formed by thermal oxidation and a polysilicon layer grown using LPCVD or PECVD. The tunneling layer is selectively grown in areas where the polysilicon layer is not present, creating a patterned structure that enhances surface passivation and reduces light absorption. The cell is prepared by sequentially depositing the tunneling layer, polysilicon layer, and other components on a semiconductor substrate.

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Solar cell design to improve efficiency by reducing front surface recombination. The solar cell has front surface field regions spaced apart from each other. Each front surface field region corresponds to a P-type or N-type conductive region on the back surface. Front and back passivation layers are used. This allows Coulomb field passivation by the front surface fields to drive carriers away from the front surface, while the back passivation prevents recombination. The front surface passivation is less affected by the front fields.

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A modified tunnel oxide layer for passivated contact (TOPCon) solar cells that improves device performance compared to conventional tunnel oxide layers. The modified oxide has a higher Si4+ content and is treated with plasma to enhance the bonding and stability of the oxide surface. This results in better passivation and lower contact resistance compared to conventional tunnel oxides. The modified oxide preparation involves growing a thin SiOx layer, followed by surface treatment with a plasma containing both hydrogen and oxygen. This modifies the oxide composition and structure to improve passivation and device performance when used in TOPCon solar cells.

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A solar cell with reduced recombination losses at side edges, comprising a substrate, a doped conductive layer, a first passivation film layer, and a first dielectric layer. The first passivation film layer completely covers the side surfaces of the substrate, and a second passivation film layer is stacked on the surface of a passivated contact layer facing away from the substrate. The second passivation film layer is made of a material including at least one of SiNx, SiONx, and SiOx.

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Solar cell with improved passivation and electrical performance, manufacturing method, and photovoltaic module and system. The solar cell has a tunnel oxide layer between the substrate and the contact layer. The tunnel oxide layer contains carbon and hydrogen dopants in addition to silicon and oxygen. This improves surface passivation and reduces defects compared to thin tunnel oxides. The carbon doping prevents pore formation during oxide growth. The hydrogen doping passivates the surface. The carbon and hydrogen co-doping enables thicker tunnel oxides for better performance.

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Solar cell with improved efficiency comprising a semiconductor substrate, a hole transport layer and an electron transport layer disposed on the substrate with an interval, and a dual-passivation layer structure comprising a first passivation layer on the hole transport layer and a second passivation layer covering both the first passivation layer and the electron transport layer. The first passivation layer is made of aluminum oxide and the second passivation layer is made of silicon oxide or silicon nitride.

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A solar cell with reduced recombination losses at side edges, comprising a substrate, a doped conductive layer, a first passivation film layer, and a first dielectric layer. The first passivation film layer completely covers the side surfaces of the substrate, and a second passivation film layer is stacked on the side of the passivated contact layer facing away from the substrate. The second passivation film layer is made of a material including at least one of SiNx, SiONx, and SiOx.

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A method for forming a passivation layer on a substrate using a combination of atomic layer deposition (ALD) and plasma-enhanced chemical vapor deposition (PECVD) techniques. The method involves depositing a first precursor layer using ALD, followed by the introduction of a spacing gas to separate the ALD and PECVD deposition zones. A second precursor layer is then deposited using PECVD in the separated zone, resulting in a passivation layer with improved uniformity and atomic packing density compared to conventional PECVD-only deposition methods.

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Bifacial solar cell with improved passivation, ablation resistance, and conversion efficiency. The cell comprises a silicon wafer with a P-type first doped layer, a silicon oxide doped layer, an intrinsic silicon layer, and an N-type second doped layer. The intrinsic silicon layer is formed by repeating deposition and plasma bombardment processes to achieve a thickness of at least 5 nm. The cell exhibits enhanced field passivation performance, reduced metal recombination loss, and improved ablation resistance.

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The latest development in perovskite solar cell (PSC) technology has been significantly influenced by advanced techniques aimed at passivating surface defects. This work presents a new approach called thermal imprinting-assisted ion exchange passivation (TIAIEP), which delivers a different approach to conventional solution-based methods. TIAIEP focuses on addressing surface imperfections in solid-state films by using a passivator that promotes ion exchange specifically at the defect sites within the perovskite layer. By adjusting the time and temperature of the TIAIEP process, we achieve substantial enhancement in the creation of a compositional gradient within the films. This optimization slows the cooling rate of hot carriers, leading to minimizing charge recombination and improving the device performance. Remarkably, devices treated with TIAIEP achieve a 22.29% power conversion efficiency and show outstanding stability, with unencapsulated PSCs maintaining 91% of their original efficiency after over 2000 h of storage and 90% efficiency after 1200 h of constant illumination. These ... Read More

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A method for preparing a heterojunction solar cell with improved cell-to-module (CTM) efficiency, comprising depositing a first passivation layer with a controlled oxygen content and thickness, and a back surface field layer, on a silicon substrate, followed by deposition of a second passivation layer and an emission electrode layer. The first passivation layer is formed by gradually increasing the proportion of carbon dioxide in the gas source during deposition, while maintaining a controlled temperature and thickness. The resulting solar cell exhibits enhanced CTM efficiency and improved output power.

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Double-sided tunneling silicon-oxide passivated back-contact solar cell with improved efficiency and manufacturability. The cell features a silicon wafer with a first semiconductor layer and passivation layer on both sides, comprising tunneling silicon-oxide layers and doped polycrystalline silicon layers. The layers are deposited simultaneously using wet processes or a tube furnace, eliminating the need for expensive flat-panel PECVD equipment. The cell's design balances passivation, conductivity, and contact resistance through optimized layer thicknesses and phosphorus-doped diffusion regions.

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A photovoltaic cell with improved anti-PID performance and power generation efficiency, comprising a substrate, a front-side passivation layer and anti-reflection layer, and a rear-side passivation layer, polarization phenomenon weakening layer, and silicon nitride layer. The rear-side passivation layer includes an aluminum oxide layer with a refractive index of 1.4-1.6 and thickness of 4-20 nm, the polarization phenomenon weakening layer includes a silicon oxynitride layer with a refractive index of 1.5-1.8 and thickness of 1-30 nm, and the silicon nitride layer has a refractive index of 1.9-2.5 and thickness of 50-100 nm.

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Edge recombination is considered hard to avoid entirely in silicon (Si) solar cells as well as Si-base solar devices, hindering their future commercialization. However, such an important issue in perovskite/silicon (PK/Si) tandem solar cells has not attracted much attention. Herein, a low-temperature, non-vacuum liquid-based edge passivation strategy (LEPS) to improve the power conversion efficiency (PCE) of PK/Si tandem solar cells is proposed. The minority carrier lifetime (eff) of the PK/Si tandem sample with 495.8 s significantly enhances to 739.7 s after passivating the Si sub-cell edge recombination. The open circuit voltage (VOC) of the PK/Si tandem solar cell increases by up to +3.8%abs from the initial state after LEPS treatment due to edge passivation, leading to the PCE of the PK/Si tandem solar cell increases by up to +1.2%abs. Finally, a monolithic PK/Si tandem cell with a PCE of 29.48% was achieved by further utilizing the LEPS, which opened up a simple and effective avenue for enhancing the PCE of PK/Si tandem solar cells and further promoting a higher photovoltaic ... Read More

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A solar cell with improved passivation effect on the front surface, comprising a silicon substrate with P-type and N-type regions on the back surface, front surface field regions on the front surface, and front and back passivation layers. The front surface field regions are selectively formed over the P-type and N-type regions, rather than covering the entire front surface, to minimize interference with the passivation layers and enhance carrier collection efficiency.

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Passivated perovskite structures for solar cells that utilize a dynamic hindered urea bond-based Lewis acid-base material to heal defects and improve device stability. The material absorbs moisture to release Lewis bases that coordinate with unpaired cationic defects, preventing detrimental molecule penetration and enhancing long-term device performance. The passivated perovskite structures achieve a power conversion efficiency of up to 22.3% and maintain over 85% efficiency after 3500 hours of storage under ambient conditions.

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Modified tunnel oxide layer for p-type top-contact (TOPCon) solar cells to improve performance. The modified tunnel oxide layer is a thin silicon oxide film with a high concentration of silicon ions (Si4+) compared to oxygen ions (O2-). This modified oxide layer is prepared by a two-step process. First, a damage-free silicon oxide layer is grown. Second, the oxide layer is plasma treated to introduce the high Si4+ concentration. This modified tunnel oxide layer has better passivation properties compared to conventional tunnel oxide layers prepared by oxidation methods. The improved passivation helps reduce recombination losses in the TOPCon cell.

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Passivation treatment is an effective method to suppress various defects in perovskite solar cells (PSCs), such as cation vacancies, under-coordinated Pb

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Passivation defects and reducing charge recombination are of great importance in enhancing 2D perovskite solar cells' (PSCs) performance. Herein, a novel additive (TEMPIC) is introduced into 2D PSCs to improve photovoltaic properties of the device, which are mainly attributed to passivated trap-states and reduced charge recombination in device.

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A surface passivation strategy using CTPC molecules is proposed to enhance the efficiency of inverted perovskite solar cells to 24.63%.

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<h2>Summary</h2> Defect passivation is regarded as an essential strategy for constructing efficient perovskite solar cells. However, the passivation in long-term operation durability has been largely ignored. Passivator concentration is usually optimized using fresh devices, whereas defect concentration increases with time during actual device operation. As a result, the initial passivators with low concentrations fail to passivate growing numbers of defects in a sustainable manner. Higher initial concentrations of passivators could in principle deal with new defects as they develop, but this strategy has not been successful so far because high concentrations of passivators are always harmful to device performance. In this study, we report a type of -conjugated passivator, the passivation effectiveness of which is independent of its concentration. This unique feature allows for high-concentration passivation without reducing device performance, which considerably improves passivation durability. This study will provide guidance for designing concentration-independent passivators and... Read More

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Functional passivation agents have been shown to effectively optimize the crystallization process and passivate defects on the surface and grain boundaries. People have conducted extensive research on the passivation mechanisms of various passivation agents to obtain more effective passivation agents. Researchers are gradually focusing on natural ingredients in the search for suitable passivation agents due to the wide variety, green color, and ease of production. As a result, the natural chlorophyll component chlorin e6 (CE6) is first combined with perovskite solar cells (PSCs) to improve their performance. Following the incorporation of CE6 into the perovskite layer, various functional groups of CE6 are used to effectively reduce traps on the perovskite surface, suppress charge recombination at the interface, improve carrier transfer rate and carrier extraction efficiency, and ultimately improve efficiency. The optimal device achieves a power conversion efficiency (PCE) of 21.14% and maintains its initial PCE of 84% after being stored in a roomtemperature air environment for 50... Read More

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Defect passivation emerges as a potent approach to enhance the performance of perovskite solar cells (PSCs). In particular, the buried interface shows a higher defect density than the upper one. Despite recent growth in buried interface passivation studies, it remains less mature than upper interface or precursor doping passivation, possibly hindering imminent efficiency breakthroughs. Herein, a chlorine-rich ammonium salt named chloroacetamidine hydrochloride (CAHC) is selected to achieve comprehensive passivation of the buried interface. CAHC effectively addresses defects in tin oxide (SnO2) and perovskite at the buried interface, significantly boosting the performance of PSCs. The power conversion efficiency (PCE) of the device based on CAHC modification reaches 24.78%. This work showcases promising advancements in buried interface passivation, offering a pathway for future breakthroughs in the performance of PSCs.

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Knowledge regarding the temperature dependence of the surface recombination at the interface between silicon and various dielectrics is critically important as it 1) provides fundamental information regarding the interfaces and 2) improves the modeling of solar cell performance under actual operating conditions. Herein, the temperature and carrierdependent surface recombination at the siliconoxide/silicon and aluminumoxide/silicon interfaces in the temperature range of 2590 C using an advanced technique is investigated. This method enables to control the surface carrier population from heavy accumulation to heavy inversion via an external bias voltage, allowing for the decoupling of the bulk and surface contributions to the effective lifetime. Thus, it offers a simple and versatile manner to separate the chemical passivation from the chargeassisted population control at the silicon/dielectric interface. A model is established to obtain the temperature dependence of the capture cross sections, a critical capability for the optimization of the dielectric layers and the investiga... Read More

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<title>Abstract</title> Interfacial trap-assisted nonradiative recombination hampers the development of single junction and tandem perovskite solar cells (PSCs). Herein, we report a rationally designed universal passivator to realize highly efficient and stable single junction and tandem PSCs. Multiple defects are simultaneously passivated by the synergistic effect of anion and cation. Moreover, the defect healing effect is precisely modulated by carefully controlling the number of hydrogen atoms on cations and steric hindrance. Due to minimized interfacial energy loss, L-valine benzyl ester 4-toluenesulfonate (VBETS) modified inverted PSCs achieve a power conversion efficiency (PCE) of 25.26% (certified 25.15%) for PSC devices and 21.00% for the modules with an aperture area of 32.144 cm². The efficiency values both are the record PCEs ever reported for the inverted PSCs using vacuum flash technology in ambition conditions. Further, by suppressing carrier recombination, the perovskite/Si tandem solar cells coupled with VBETS passivation deliver a PCE of 30.98%. This work ... Read More

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Solar cells are crucial for addressing global energy issues, with research focused on improving their efficiency. This study examines the impact of doping concentration gradients on solar cell performance. Doping involves adding impurities to a semiconductor, affecting charge carrier mobility and recombination rates. The spatial distribution of these dopants, known as the doping concentration gradient, is essential for optimizing solar cell characteristics. This research theoretically analyzes the effects of doping gradients on potential differences, electric fields, and recombination rates in semiconductors. We explore how doping creates potential differences and electric fields that guide charge carriers and enhance mobility. Additionally, we study how doping gradients can control recombination mechanisms, thereby improving the electrical performance of solar cells. Using modeling and simulation techniques, we derive the optimal doping gradient to maximize efficiency. Our findings suggest that an optimal doping gradient minimizes recombination rates and enhances charge carrier mobi... Read More

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Defect passivation emerges as a potent approach to enhance the performance of perovskite solar cells (PSCs). In particular, the buried interface shows a higher defect density than the upper one. Despite recent growth in buried interface passivation studies, it remains less mature than upper interface or precursor doping passivation, possibly hindering imminent efficiency breakthroughs. In addition, most of the recent buried passivation work passivates only one or two kinds of defects, the remaining defects at the buried interface will still damage the performance of PSCs. Herein, a chlorine-rich ammonium salt named chloroacetamidine hydrochloride (CAHC) is selected to achieve comprehensive passivation of the buried interface. CAHC effectively addresses various defects in tin oxide (SnO2) and perovskite at the buried interface, significantly boosting the performance of PSCs. The power conversion efficiency (PCE) of the device based on CAHC modification reaches 24.78%. This work showcases promising advancements in buried interface passivation, offering a pathway for future breakthrough... Read More

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This chapter explores the pivotal role solar cells play in the transition towards sustainable energy sources. An overview of various generations of solar cells is provided, extending from silicon-based to thin film technologies such as CdTe "Cadmium Telluride" and CIGS "Copper Indium Gallium Selenide" to novel structures and materials encompassing perovskite dye-sensitized and organic. Emerging solar cells such as tandem and multijunction structures are also highlighted. Moreover, a detailed review on the passivation methods and materials employed in various generations of solar cells is provided, along with a case study aimed to examine the effect of bulk passivation on the lifetime and stability of perovskite films. Passivation techniques aim to address challenges such as surface and interface defects that can lead to non-radiative recombination of charge carriers. Passivation minimizes defects and optimizes the electronic properties of solar cell materials. Further advancements in passivation techniques and materials are essential to uplift the performance and reliability of solar... Read More

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Defects both in bulk and at the interfaces serve as charge trapping sites for nonradiative recombination and as ion migration pathways, resulting in degradation of perovskite solar cell efficiency and stability. In this work, a strategy for simultaneous passivation of both bulk and interfacial defects is reported. For bulk passivation polystyrene (PS) is used as an additive in the perovskite precursor which reduces the structural defects by forming larger defectfree grains. While the FPEAI cation is used to passivate the interfacial defects, present at both perovskite HTL/ETL interfaces. Furthermore, by conducting control measurements with just bulk modification (PS), just interface modification (FPEAI), and a combination of both, the role of individual defect passivation strategies is decoupled. As a result of simultaneous bulk as well as interfacial passivation, the modified perovskite solar cell shows the highest efficiency of 22.32% with a high V oc of 1.14 V and fill factor of 80%. Moreover, the cells have excellent stability retaining 92% and 99% of their initial efficiency ... Read More

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A MOF material is used to passivate the hole transport layer in perovskite solar cells, improving stability and efficiency. The MOF material is deposited on the nickel oxide hole transport layer to prevent degradation of the perovskite absorption layer, which occurs when nickel ions come into direct contact with the perovskite material. The MOF material replaces the need for auxiliary organic macromolecules, enabling higher performance and longer lifespan of perovskite solar cells.

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Solar cell design and manufacturing process to improve efficiency by reducing recombination at the cell edges. The cell has an anti-reflection layer or second passivation layer extending onto some of the side surfaces in addition to covering the top and bottom surfaces. This reduces recombination at the edges compared to cells where only the top and bottom surfaces are passivated.

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A hybrid transmission layer for solar cells comprising a first material with strong passivation properties and a second material with high carrier extraction efficiency, wherein the two materials are mixed to form a single layer that simultaneously achieves both functions. The hybrid layer enables improved open circuit voltage and fill factor in perovskite solar cells, outperforming devices using separate passivation and extraction layers.

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A method for improving the efficiency of P-type passivated emitter and rear cell (PERC) solar cells by introducing a novel laminated passivation structure. The structure comprises a silicon substrate with a first SiO2 film, an Al2O3 layer, a SiOxNy film, and a first SiNx film sequentially deposited on the back surface. The aluminum back field passes through these layers to connect with the substrate, reducing recombination and increasing long-wave reflection. The structure enables a 1% or more efficiency improvement in PERC cells, with the potential to further enhance efficiency beyond current limits.

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A perovskite solar cell with improved stability and a method for manufacturing the perovskite solar cell. The cell comprises a perovskite layer and a passivation layer. The perovskite layer is formed through a solution process, and the passivation layer is formed through an annealing treatment of the perovskite layer. The passivation layer contains an aza fused bicyclic compound and/or an organic salt formed from the aza fused bicyclic compound and an acid, each fused ring in the aza fused bicyclic compound is independently a five-membered or six-membered saturated ring, unsaturated ring or aromatic ring, the fused ring of the aza fused bicyclic compound contains 1-5 nitrogen atoms, and the above-mentioned fused ring is an unsubstituted ring or a ring substituted with one or two substituents having 1-3 carbon atoms.

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A perovskite solar cell that enhances efficiency and stability through optimized interface passivation. The cell employs a precise concentration range for the interface passivation material, maintaining a concentration between 0.1-40 mmol/L. This controlled concentration prevents excessive passivation while preventing tunneling through the material. The passivation layer is prepared through a novel process that selectively targets specific defects in the perovskite surface, ensuring complete passivation while minimizing recombination. The cell's back electrode is prepared by scraping and evaporating the material, resulting in a uniform surface. The cell's performance and stability are further enhanced through the use of a specific electron transport layer and hole transport layer.

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The observed open circuit voltages in best performing solar cells are explained outside of the recombination paradigm, based on such factors as electrostatic screening, MeyerNeldel effect, and lateral nonuniformities. The underlying concept of suppressed recombination presents a long neglected alternative pathway to efficient photovoltaic. The criteria of suppressed recombination and effective charge carrier extraction are consistent with the data for best performing solar cells.

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A modification layer for hybrid perovskite solar cells that enhances efficiency by passivating defects and optimizing energy levels at the interface between the perovskite layer and the underlying composite layer. The modification layer is formed from small organic molecules or polymers with specific functional groups that interact with both the composite layer and the perovskite layer to improve charge transport and reduce recombination.

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On top of a crystalline silicon wafer, heterojunction solar cells have a thin layer of amorphous silicon (a-Si) placed on it. The efficiency of heterojunction solar cells can be increased by decreasing the electron complex loss by adding an inherent passivation layer to a monocrystalline silicon (c-Si) substrate. In this study, we examine the development of the intrinsic passivation layer deposition technique on c-Si substrates over the previous ten years by several research teams. First, a description of the structure, benefits, and passivation of heterojunction solar cells is given. Following that, the impact of modifying process variables on the functionality of the passivation layer and cell efficiency is explored in terms of the passivation material, hydrogen dilution ratio, substrate temperature, and post-deposition annealing. Last but not least, the ideal process parameters are summed up and potential future research areas are predicted. One of the best ways to increase the conversion efficiency of heterojunction solar cells is through surface passivation technology, and futur... Read More

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Silicon heterojunction (SHJ) solar cells are increasingly attracting attention due to their low-temperature processing, lean steps, significant temperature coefficient, and their high bifacial capability. The high efficiency and thin wafer nature of SHJ solar cells make them ideal for use as high-efficiency solar cells. However, the complicated nature of the passivation layer and prior cleaning render a well-passivated surface difficult to achieve. In this study, developments and the classification of surface defect removal and passivation technologies are explored. Further, surface cleaning and passivation technologies of high-efficiency SHJ solar cells within the last five years are reviewed and summarized.

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A solar cell with improved light absorption efficiency, comprising a substrate, a passivation stack, a tunneling oxide layer, and a doped conductive layer. The passivation stack includes an oxygen-containing dielectric layer, a silicon nitride layer, and a silicon oxynitride layer, with a nitrogen-rich interface between the silicon nitride and silicon oxynitride layers. The silicon nitride layer has a higher refractive index than the silicon oxynitride layer, reducing internal reflection and emission of light. The silicon oxynitride layer has a higher refractive index than the oxygen-containing dielectric layer, enabling external light to enter the substrate at a smaller incident angle.

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Solar cell with improved light absorption efficiency, comprising a substrate with a front and rear surface, a dielectric passivation layer on the front surface, a silicon nitride layer with a specific nitrogen-to-molybdenum ratio, and a silicon oxynitride layer with a specific oxygen-to-nitrogen ratio, and a tunneling oxide and doped conductive layer on the rear surface.

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A solar cell and photovoltaic module that improves light absorption efficiency by incorporating a specific dielectric layer structure. The solar cell features a substrate, a first passivation stack with a high-density, oxygen-rich dielectric layer, a tunneling oxide layer, a doped conductive layer, and a second passivation layer. The high-density, oxygen-rich dielectric layer prevents sodium ion penetration and enhances light absorption. The photovoltaic module comprises a cell string, a package adhesive film, and a cover plate, with each solar cell in the string featuring the optimized dielectric layer structure.

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Development of high-efficiency solar cells is very important for clean energy society based on photovoltaics. Multi-junction solar cells are very attractive as high-efficiency solar cells because 2-junction and 3-junction solar cells have high-efficiency potential of more than 36% and 42%, respectively. This paper overviews present status of multi-junction solar cells. As a results of reducing non-radiative recombination and resistance losses, 39.5% efficiency has been demonstrated with 3-junction solar cell. In addition, understanding and controlling defects, surface recombination and interface recombination are shown to be very important in order to improve efficiency of multi-junction solar cells. Brief overview for Si tandem solar cells composing of III-V, II-VI, chalcopyrite, perovskite top cells and Si bottom cell is also presented.

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Solar cell with enhanced passivation and conversion efficiency through a novel donor material film layer. The film is manufactured between the semiconductor substrate and the amorphous silicon interface, where it prevents silicon epitaxial growth between the crystalline silicon interface and the amorphous silicon interface. This architecture improves passivation, reduces parallel resistance, and enhances fill factor, leading to improved conversion efficiency of the solar cell.

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A method for passivating metal halide perovskite surfaces using an organic dye derivative that undergoes thermal conversion to form a stable dye. The dye is dissolved in a liquid and applied to the perovskite surface through spin-coating or drop-casting. The liquid and dye mixture undergoes thermal annealing to convert the dye derivative into a stable, fully dissolved dye that forms a protective layer on the perovskite surface. This approach enables the creation of stable perovskite solar cells through surface passivation without the need for conventional passivation agents.

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The full potential of perovskite solar cells (PSCs) is limited by charge-carrier recombination, due to the imperfect passivation methods. Here, interfacial recombination loss of field-effect and chemical passivation mechanisms is quantified. It was found that a favorable alignment of energy levels can provide very good field-effects to reduce minority carriers, and suppresses interfacial recombination losses more effectively than chemical passivation. To obtain high-efficiency PSCs, two-dimensional (2D) perovskites are promising candidates, which offer powerful field-effects and only require modest chemical passivation at the interface. Owing to promoted passivation and charge-carrier extraction, the power conversion efficiency of a 2D/3D heterojunction PSC was boosted to 25.32% (certified 25.04%) for small-size devices and to 21.48% for a large-area module (with a designated area of 29.0 cm2). Ion migration is also suppressed by the 2D/3D heterojunction so that the unencapsulated small-size devices maintain 90% of the initial efficiency after 2000 h of continuous operation at the ma... Read More

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Because of high efficiencies and low-cost fabrication, perovskite solar cells (PSCs) have drawn great attention. Although an impressive power conversion efficiency (PCE) of 26.1% has been achieved, there is still room for further improvements before these cells reach their theoretical limit. One major factor limiting the PCE of PSCs is defect-induced recombination. Defect passivation strategies have proven useful in improving the PCE of PSCs. In this review, we first briefly summarize the passivation methods and theories for other solar cell technologies, including silicon solar cells, cadmium telluride solar cells and copper indium gallium selenide solar cells. We then introduce the various types of defects present in PSCs and the corresponding passivation methods. Finally, we provide future perspectives and propose that it is exigent to establish a better understanding of the relationship between the properties of passivation materials and their defect passivation effects on perovskite materials and device performance. To understand this relationship, machine learning can be a powe... Read More

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A simple passivation strategy using a common fluorinated salt is reported that seeks to enhance the photovoltaic performance and long-term stability of halide perovskite solar cells. Tetra-n-butyl ammonium hexa-fluorophosphate is used as a passivating agent to mitigate the surface defects on the perovskite and impede the ion mobility by virtue of H-bonding. In addition, the presence of fluorine atoms causes strong hydrophobicity, which in turn improves the moisture stability in perovskite solar cells. More details can be found in article number 2200211, Samrana Kazim and co-workers.

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