Techniques for Passivation Layer Stability of Solar Cells Under High Temperature

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 tunnel oxide passivated contact (TOPCon) solar cell with improved efficiency, comprising a tunnel oxide layer and a doped polysilicon layer, wherein the doped polysilicon layer is replaced with a transparent conductive oxide (TCO) layer, and a first passivation layer is formed on the TCO layer. The TCO layer is preferably a doped metal oxide, such as aluminum-doped zinc oxide, and the first passivation layer is preferably aluminum oxide or silicon nitride. The solar cell exhibits improved fill factor and efficiency compared to conventional TOPCon cells.

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A solar cell with improved light absorption efficiency and isolation properties, comprising an N-type silicon substrate, a passivation layer, a three-layered antireflection film, and a tunneling dielectric layer. The antireflection film includes a silicon nitride layer, a silicon oxynitride layer, and a silicon oxide layer, stacked in that order. The passivation layer is an aluminum oxide layer between the substrate and the antireflection film. The tunneling dielectric layer is on the rear surface of the substrate.

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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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Solar cell with improved thermal stability and manufacturing method thereof, comprising a first electrode layer, an active layer, a barrier layer, and a second electrode layer stacked in sequence. The barrier layer comprises an n-type semiconductor oxide, such as tin oxide, titanium oxide, zinc oxide, indium oxide, or gallium oxide, which blocks the migration of holes toward the cathode and prevents corrosion of the second electrode layer. The barrier layer is formed using atomic layer deposition and has a lower HOMO energy level than the active layer. The solar cell module is manufactured by forming the barrier layer on the active layer and the second electrode layer on the barrier layer, with the second electrode layer having a longitudinal portion extending toward the first electrode layer.

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Photoelectric conversion element with improved sealing layers for high-temperature and high-humidity environments. The element comprises a photoelectric conversion layer, conductive layer, first sealing layer of inorganic metal oxide, nitride, oxynitride, or fluoride, and second sealing layer of polymer or nitride coating. The inorganic first sealing layer prevents oxygen and atomic oxygen penetration, while the second sealing layer provides additional protection against environmental degradation.

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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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This chapter provides a comprehensive examination of major carrier-induced degradation mechanisms impacting silicon solar cells, including boron-oxygen related carrier induced recombination (BO-CID), light and elevated temperature-induced degradation (LeTID), copper-related light-induced degradation (Cu-LID), and surface-related degradation (SRD). These mechanisms reduce device performance upon carrier injection, challenging the solar photovoltaic industry as they may exceed module warranty periods. Temperature fluctuations further exacerbate these effects, increasing the levelized cost of electricity (LCOE). However, significant progress has been made in developing mitigation processes. Researchers and industry professionals ensure long-term stability under standard operating conditions through optimisation studies and procedures. This chapter compiles decades of research, shaping our current understanding of these degradation phenomena and offering strategies for effective management.

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Solar cells with improved chemical resistance against contaminants, particularly sodium ions, through the incorporation of an aluminium oxide barrier layer deposited via atomic layer deposition. The barrier layer is capable of reducing contaminant penetration and maintaining solar cell efficiency under damp heat conditions.

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Passivation contact structure for solar cells with improved hydrogen passivation and reduced thermal treatment complexity. The structure features a rarefied region in the first silicon oxide layer, where the silicon oxide content is reduced, allowing for enhanced hydrogen diffusion and passivation. The rarefied region is created by local thinning of the first silicon oxide layer, which enables efficient hydrogen passivation while maintaining the structural integrity of the contact.

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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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High-efficiency back-passivation crystalline-silicon solar cell with improved passivation and reduced silicon island formation. The cell features a novel laminated back passivation structure comprising SiO2, AlOx, SiNx, and SiOxNy layers, which provides enhanced surface passivation and reduced defect states. The structure is designed to prevent hydrogen-induced silicon island formation during high-temperature processing, enabling improved long-wave response and short-circuit current.

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A solar cell and its preparation method that improves photoelectric conversion efficiency by preventing electroluminescence (EL) problems. The method involves a controlled sintering process that breaks chemical bonds in the passivation film and anti-reflective coating without allowing hydrogen to escape, thereby maintaining passivation and preventing recombination centers. The process also ensures effective ohmic contact between the electrode and silicon substrate.

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Most crystalline Si based solar cells, e.g. passivated emitter and rear cells, rely on SiNy:H and AlOx/SiNy:H passivation layers. In this work, the long-term behavior of minority charge carrier lifetime in such symmetrically passivated samples during illuminated annealing at elevated temperatures is investigated by means of photoconductance decay based lifetime measurements, corona charging and capacitance voltage measurements. Thereby, AlOx layers, which are known to reduce H in-diffusion due to their barrier properties, deposited by atmospheric pressure chemical vapor deposition as well as by atomic layer deposition were considered enabling a comparison of different deposition techniques. The frequently published behavior of the bulk related degradation could be confirmed and the qualitative correlation between maximum defect density and the changing total amount of H in the Si bulk due to the barrier properties of the individual layers dielectric layers could be shown. Furthermore, for the subsequently observed degradation accelerated by a treatment at higher temperatures, literat... Read More

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A photovoltaic cell with enhanced surface passivation that combines the benefits of silicon oxide and aluminum oxide passivation layers. The cell features a silicon substrate with two main surfaces, where a POx-Al composite layer covering the first main surface is followed by a capping layer structure that covers the POx-Al composite layer. The POx-Al composite layer is a mixed AlPxOy film that combines the advantages of both materials, with a specific ratio of phosphorus to phosphorus+aluminum that balances charge state density and interface state reduction. The capping layer structure is a stable aluminum oxide layer that prevents interface state accumulation while maintaining passivation. This composite layer stack provides superior surface passivation compared to conventional materials, particularly for n-type silicon substrates, while maintaining stability under atmospheric conditions.

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Silicon heterojunction (HJT) solar cells have world-leading efficiencies due to outstanding surface passivation. Yet, maintaining their performance during the lifetime of a photovoltaic module requires excellent quality and stability of the surface regions. It is well known that HJT solar cells can show an increase or reduction in performance under illumination, and this instability has been related to changes in the surface regions. This work investigates the stability of surface passivation in HJT solar cells by modelling the injection-dependent minority carrier lifetime of a range of symmetrically a-Si passivated silicon wafers. Fixed charges and defects at the interface are varied in the model to find the best fit to the injection-dependent lifetime before and after a high-intensity illumination treatment. The results indicate that the laser process induces an increase in field effect passivation at the surface, which is then reduced upon storage in the dark. The results show that lifetime spectroscopy is a useful tool to investigate the nature of a-Si passivation degradation.

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High quality surface passivating films are essential for high efficiency solar cells. In this work, we present our study about the silicon surface passivation performance of thermal atomic layer deposited (T-ALD) ZnOx/AlOx stack deposited using super-cycle approach. Super-cycle approach is composed of three cycles of DEZ-DI water system followed by one cycle of TMA-DI water system. The number of super-cycles is varied to change the film thickness. Excellent passivation with surface recombination velocity 7 cm/s was achieved under this study for hydrogen annealed films. The passivation mechanism is related to the saturation of defects by hydrogen after annealing and further improvement in fixed oxide charges by one order of magnitude (1010 to 1011 cm2). Hydrogenation at the optimum temperature (450C) involves the transport of hydrogen atoms towards the interface and their interaction with dangling bonds at the Si surface leading to the effective passivation. The optical transmittance of the film in the visible region of the spectrum is found to be >95 % for all the deposited films... Read More

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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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<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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In this paper, an effective P+ emitter passivation scheme was proposed by continuously optimizing the passivation layer on the front surface of N-type tunnel oxide passivated contact (TOPCon) solar cells, that was using SiOx/AlOx/SiNx tri-layer passivation stack. The SiOx/AlOx/SiNx stack combined the benefits of the chemical passivation effect of SiOx and the field-effect passivation of SiOx/AlOx stack, resulting in high-quality passivation for boron-doped emitter. Three different passivation schemes of SiNx, AlOx/SiNx and SiOx/AlOx/SiNx were respectively prepared on the front surface of N-type TOPCon solar cells. It was revealed that the cells with SiOx/AlOx/SiNx stack had a superior conversion efficiency, while the SiOx thickness significantly influenced the surface passivation. Through optimization of SiOx thickness in the SiOx/AlOx/SiNx stack, the optimal deposition period for SiOx was 4 cycles by the plasma-enhanced atomic layer deposition (PEALD) process. The N-type TOPCon solar cells with SiOx/AlOx/SiNx stack on the front surface exhibited the highest performances with a conve... Read More

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