Institutions all over the world currently work intensively on the development of solar cells based on lead perovskite that will be ultra-stable, high-performance, economic, and will have a minimal environmental impact. One concern is the potential release of lead into the environment. This question notably arises in situations in which the encapsulant and glass protective materials could perhaps no longer serve as insulation against the penetration of water and the leak of dissolved lead-containing substances due to climatic episodes such as hailstorms. Here, damaged centimetric lead perovskite layers which mimic partially photovoltaic cells were leached in rainwater. Long lasting water-soaking (during 146 days) tests and water-dripping tests (during 1 year) were implemented. For the water-dripping test, the samples were exposed to 80% relative humidity at ambient temperature with optional drying period at 40°C in ambient atmosphere. Throughout the year, they were subjected to occasional episodes of simulated rain. The results show that the cells released lead and iodine into the solution. Drying the cells at 40°C (simulating a day of strong sunshine in dry atmosphere) meant that the amounts of lead released into solution during the following rainy episode were decreased by a factor of 2 to 3. On the one hand, from the quantities of lead released over time, a ”worst case” scenario of a bad weather country gives a lead release value of 0.5 g.m-2.year-1. On the other hand, considering a more realistic scenario (sunny country with sample drying) the lead release would be 0.05 g.m-2.year-1.

Perovskite photovoltaic (PV) cells have achieved a record 26.7% efficiency, but improvements in stability against humidity, temperature shifts, and light exposure remain crucial. In this work, we explored mesoporous carbon-based perovskite (c-PSC) devices because of carbon's stability and the elimination of a heat-sensitive hole transport layer. Encapsulation materials exhibiting promising properties with silicon PV, including a thermoplastic polyolefin encapsulant, were applied under different lamination conditions to investigate the impact on c-PSC devices' durability, which is a novel study for this specific combination of materials. Inadequate curing can compromise adhesion, reduce moisture resistance, and accelerate perovskite decomposition under light exposure. Increasing the lamination temperature by 20 degrees C allowed samples to withstand 1000 h of damp-heat conditions, with a 30% reduction in efficiency, while lower temperature lamination caused immediate performance drops. While light exposure remained highly degrading, higher lamination temperatures delayed damage, preserving 2.5% of the initial power conversion efficiency after 400 h of aging and slowing perovskite decomposition.

Encapsulation is a critical topic to ensure the successful implementation of perovskite photovoltaics. Recently, vacuum lamination has been shown as a promising approach that combines compatibility with current industrial processes in conventional photovoltaic (PV) manufacturing and suitability to achieve good results with perovskites. Here, we explore some of the attractive encapsulation materials in terms of their ability to prevent moisture ingress, withstand elevated temperatures, and have suitable mechanical properties to avoid thermomechanical issues. We utilized the previously suggested concept of the "perovskite test," an optical test with simple sample fabrication, for evaluating encapsulation quality and validated the findings with the full solar cell stack. Unsurprisingly, encapsulants without an edge sealant showed insufficient protection from moisture. Ionomer in combination with butyl edge seal showed the best barrier properties; however, this stack led to rapid delamination of the cell layers in thermal cycling tests. Configuration with only edge sealant does not have such an issue in principle (no mechanical stress applied), but an absence of the polymer in the stack is unfavorable in terms of optical design and sometimes showed perovskite degradation that we assign to trapped moisture in the butyl itself. Polyolefin with butyl edge sealant is not free of degradation but showed the most promising compromise by passing the damp heat test and showing fewer issues in the thermal cycling experiments. In general, our material study and optimization presented in this manuscript show that a holistic approach is needed when choosing an optimal encapsulation scheme for perovskite devices.

Fabricating tin dioxide (SnO2) electron selective layers (ESL) by atomic layer deposition (ALD) can be of high interest for perovskite-based solar cell development since it offers a number of advantages over solution-based processes. However, ALD-grown SnO2 ESL has usually been reported to yield limited cell efficiency compared to solution-processed SnO2 ESL, without the causes being clearly identified. This is why we here conduct a thorough interface study using a set of complementary techniques. For this purpose, ALD-grown SnO2 thin films are characterized in a systematic comparison with reference solution-processed SnO2. Energetics analysis by ultraviolet photoelectron spectroscopy (UPS) points out an unfavorable band bending at the ALD-grown SnO2/perovskite interface. Chemical characterization by time-of-flight secondary ion mass spectroscopy (ToF-SIMS) and hard X-ray photoelectron spectroscopy (HAXPES) profiling unveils an unexpected lack of oxygen at the ALD-grown SnO2/perovskite interface, which may play a direct role in observed performance limitations.

The record photovoltaic performance of perovskite solar cells is constantly increasing, reaching 26% currently. However, there is a crucial need for the development of simple architectures that are compatible with large-scale industrialization and possess adequate stability. The aim of the work presented here is to compare the efficiency of glass–glass and glass–backsheet encapsulations for carbon-based perovskite solar cell application, which possesses a great potential for industrialization. This was conducted by first separating the relative effects of humidity and heat. A time evolution of the macroscopic power conversion efficiency (PCE) was performed, together with specific characterizations in order to scout the origin of flaws and degradations. A significant contribution of the paper is the identification of both TiO2 and carbon layers as barriers against moisture permeation, which inhibit moisture paths through the interfaces. This is the origin of the equivalent durability of both studied systems, even if the glass–backsheet encapsulation was found to be less efficient than the glass–glass encapsulation at protecting perovskite from damp-heat aging when TiO2 or carbon layers are not used.

This work presents a comparative study between tin(IV) oxide (SnO2) thin films deposited by spin coating or Atomic Layer Deposition (ALD) to be used as an electron selective layer (ESL) in perovskite/silicon tandem solar cells. This study is motivated by the usually lower performances of ESL made of ALD-grown SnO2 compared to ones made via solution-based processes. Chemical, electrical, optical and topographical properties of each type of film were investigated. In an attempt to link thin film properties to device characteristics, single-junction perovskite solar cells and perovskite/ silicon tandem solar cells were fabricated. Despite the high-quality electronic and optical properties of ALDgrown SnO2, perovskite-based solar cells employing such film showed limited performances. Characterization of perovskite films properties grown on both type of SnO2 did not rise significant differences and tends to indicate some hindering factors at the ALD-grown SnO2/perovskite interface. Kelvin force probe microscopy characterisation unveiled a larger workfunction for ALD-grown SnO2, which could create a potential barrier for electron extraction from the perovskite.

The efficiency of perovskite solar cells is continuously increasing in the last decade, reaching up to 25.5%. However, further investigation is required to improve the stability of such devices, starting with the identification of the degradation mechanisms upon exposure to harsh environments. For an increased durability of the devices at high levels of moisture and temperature, a mesoporous structure was adopted, utilising carbon electrode and omitting the hole transport layer, which is susceptible to heat. Furthermore, an adequate encapsulation is required for additional protection against moisture ingress. This scientific work aims at identifying the degradation paths followed by perovskite cells when they are subjected to high temperature and humidity levels. To achieve this goal, full carbon-based perovskite (c-PSC) cells and modified devices were encapsulated with various concepts, and aged either at damp-heat conditions (85% RH / 85°C) or at high temperature (85°C) in nitrogen environment. Moreover, different characterisation techniques were compared for the identification of the degradation mechanisms. The results indicate that perovskite reacts with moisture after 1000 hours of damp-heat exposure, while heat degradation occurs much earlier. The latter is detrimental and requires further improvement of the durability of the perovskite absorber to heat.

Abstract Thin Film Encapsulation (TFE) using a multilayer stack of inorganic and organic films is now a well-known encapsulation technology for organic electronics such as Organic Light-Emitting Diodes (OLED). It shows excellent gas barrier properties with very low WVTR, and good compatibility with flexible and transparent substrates. In this study, low-temperature Atomic Layer Deposition (ALD) serves for the fabrication of high performance Al2O3 inorganic barrier layers. A silica nanocomposite polymer serves as a moisture-stable interface layer in a very high barrier quality architecture of the kind [Al2O3 (25 nm)/nano-CP (1 µm)/Al2O3 (25 nm)/nano-CP (5 µm)]. The helium and water vapor quantitative gas permeation properties (HeTR and WVTR) of different intermediate TFE architectures deposited on plastic substrate (PET) are analyzed using a permeameter. These results are compared to an accelerated weathering test standard, for monolithic TFE deposited in-situ on top-emitting OLED circuits. On PET, the best TFE stack decreases the steady state permeation rate by a factor 1180 and 1650 respectively for helium and water vapor. Onto a top-emitting OLED, the long-term black spot occurrence rate drastically decreased from 100 %.h− 1 to 3.210− 3 %.h− 1, attesting the successful implementation of this TFE architecture from ex-situ on PET substrate to in-situ on OLED circuits.

Materials with high barrier properties against oxygen are required for the packaging of many sensitive foods. Since commodity polymers lack these properties, additional barrier materials are used in plastic-based barrier packaging. These are usually more expensive than commodity polymers and, in higher fractions, also make recycling more difficult. Current developments, therefore, aim at barrier layers that are as thin as possible but retain the barrier properties. One approach is to incorporate nanoparticles into these layers. In this study, the barrier properties of nanocomposite coatings, consisting of unmodified polyvinyl alcohol (PVA), and dispersed stick-shaped halloysite (Hal) or platelet-shaped montmorillonite (MMT) silicate nanoparticles, were investigated. The PVA was dissolved in aqueous nanoparticle dispersions, which were prepared by mechanical shearing, to produce the so-called "nanolacquer." Nanolacquers with nanoparticle concentrations of 7, 30, and 47 vol% with respect to PVA were applied in a single process step with k-bar on a polypropylene substrate film. The integration of 30 vol% platelet-shaped MMT enhances the barrier performance in comparison to pure PVA by a factor of 12 and 17 for oxygen and helium, respectively. Scanning electron microscopy (SEM) shows a homogeneous distribution and a parallel alignment of the nanoparticles within the coated layer. An increase in the crystallinity of PVA was observed due to the nanoparticle integration as demonstrated by x-ray diffraction (XRD) measurements. The investigation by Fourier transform infrared (FTIR) spectroscopy and the activation energy of the permeation coefficient indicate an interaction between the nanoparticles and the PVA. The theoretically calculated values for barrier enhancement accord well with the experimental values, which emphasizes that the gas barrier improvement for oxygen and helium is mainly dominated by the tortuous path effect.

Organic–inorganic hybrid perovskite solar cells have become one of the most promising photovoltaic technologies with conversion efficiency exceeding 25%. Increasing the efficiency of the perovskite solar cells is one of the most important challenges in the photovoltaic domain. The development of good hole transport layers (HTLs) is crucial for high-performance perovskite-based photovoltaic systems. Furthermore, it is important to accurately optimize the energy level matching between perovskites and hole transport materials via better charge collection. This work explores the effect of the HTLs on the growth process, morphology and crystallinity of the perovskite active layer and their impacts on the photovoltaic performance. Devices with planar inverted architecture ITO/HTL/MAPbI3-xClx/PC60BM/BCP/Ag were fabricated using a one-step deposition method. The effects of the use of various HTL materials and the effect of the thermal annealing treatment of this layer were investigated. Morphological and microstructural analyzes of the perovskite films were carried out by scanning electron microscopy, X-ray diffraction. The optical properties in particular the absorption and the recombination process were studied by UV–vis absorption spectroscopy and photoluminescence spectroscopy. The photoelectric properties were investigated by photocurrent–voltage characteristic curves.

We report a fast, reliable and non-destructive method for quantifying the homogeneity of perovskite thin films over large areas using machine vision. We adapt existing machine vision algorithms to spatially quantify multiple perovskite film properties (substrate coverage, film thickness, defect density) with pixel resolution from pictures of 25 cm 2 samples. Our machine vision tool—called PerovskiteVision—can be combined with an optical model to predict photovoltaic cell and module current density from the perovskite film thickness. We use the measured film properties and predicted device current density to identify a posteriori the process conditions that simultaneously maximize the device performance and the manufacturing throughput for large-area perovskite deposition using gas-knife assisted slot-die coating. PerovskiteVision thus facilitates the transfer of a new deposition process to large-scale photovoltaic module manufacturing. This work shows how machine vision can accelerate slow characterization steps essential for the multi-objective optimization of thin film deposition processes.

While impressive efficiency progress has been achieved for perovskite-based solar cells, process upscaling represents one of the main remaining hurdles to commercial applications. In this contribution, the development of a scalable method to process perovskite layers in air is presented. Combining gas-quenching and optimized precursors stoichiometry, pinholes-free films were obtained via low temperature solution processing. When integrated in single junction devices, power conversion efficiency > 18% was achieved on 10 cm 2 devices.

One of the major bottlenecks of perovskite photovoltaic modules fabrication is the homogeneous deposition of perovskite material on large-area substrates. Here, we show that slot-die coating technique combined with synergistic gas quenching and substrate heating can produce compact, homogenous and reproducible Cs0.16FA0.84Pb(I0.088Br0.12) 3 perovskite films. We demonstrate the fabrication of perovskite solar cells (PSCs) in a planar (n-i-p) device configuration and attain power conversion efficiency (PCE) of 18% over 0.09 cm2 device active area. The versatility of this crystallization strategy, which eliminates the need for complex solvents or additive engineering, was studied using planar SnO2- and TiO2-coated FTO substrates. Our study provides greater insights into achieving controlled coating and homogeneous crystallization of perovskite films over large-area substrates (similar to 10 x 10 cm2) necessary for the commercialization of this technology.

Over the last two decades, organic photovoltaic (OPV) devices have seen their efficiency increase, while long-term stability and upscaling have been demonstrated for first-generation modules. Since the maturity level of this technology has now improved, techniques for rapid quality control have become relevant. Imaging techniques such as photo- and electroluminescence have already been used for this purpose. However, defects could only be localized either in the active layer or in interface layers, without being able to distinguish between defects located in the ETL from those within the HTL. Here, we present a simple method to unambiguously discriminate between ETL and HTL defects. Furthermore, we demonstrate the strong impact of HTL thickness on the detected photoluminescence signal. Our approach will help avoid misinterpretations in luminescence experiments and gain an understanding of device failure during processing or aging.

Hybrid organic–inorganic halide perovskite solar cells (PSCs) have gained exceptional attention in photovoltaic fields with an attractive yield of 25%. Characterization tools present as an important means that would help define optimized treatment parameters at an early stage of device manufacturing, instead of measuring the J (V) curves of complete solar cells. In this work, devices with planar NIP architecture ITO/SnO2/MAPbI3-xClx/HTL/Au were elaborated using one-step deposition method. The effects of annealing temperature of the ETL layer (SnO2) and various materials as an HTL layer have been studied. In parallel, X-ray diffraction, UV–visible absorption and photoluminescence were performed as well as photoluminescence spectroscopy, to analyze the active layer crystallinity, absorption properties and to probe charge transfer between perovskite and interface layers. By varying processing parameters, device efficiency could be raised from 10% up to 13.2%.

To increase the lifetime of organic photovoltaic (OPV) devices and pass European lifetime standards, some encapsulation systems are often used to limit the exposition to oxygen and humidity of solar cells. Despite this progress, the damages induced by the encapsulation process are scarcely studied in literature. In this article, the consequences of the common roll-to-roll and vacuum lamination approaches are investigated and compared. The losses of performances are first followed induced by both the encapsulation itself and in a damp heat ageing. The vacuum lamination seems harmless for the solar cells. However, a significant damage is evidenced, even with a relatively mild roll-to-roll encapsulation. The degradation mechanisms are further investigated by complementary imaging characterization tools: photoluminescence/electroluminescence imaging and spectroscopy, laser-beam-induced current mapping, and correlated toJ(V) curves. The recent advancements in the optoelectronic domain may allow linking cell performance to localized flaws. It appears that, although the processing conditions are rather homogeneous, the resulting degradation ends up with a strong localization feature.