Published: January 2025

Journal: Progress in Photovoltaics

Abstract:

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.

Cite:

Emery, Q., Dagault, L., Khenkin, M., Kyranaki, N., de Araújo, W., Erdil, U., Demuylder, M., Cros, S., Schlatmann, R., Stannowski, B. and Ulbrich, C. (2025), Tips and Tricks for a Good Encapsulation for Perovskite-Based Solar Cells. Prog Photovolt Res Appl, 33: 551-559. https://doi.org/10.1002/pip.3888

Published: March 2025

Journal: ACS Energy Letters

Abstract:

Perovskite solar cells (PSCs) are expected to transform the photovoltaic market; however, their unproven operational stability requires urgent attention, particularly accelerated aging tests. Currently, illumination is the primary stressor in such tests. In this work, we present an accelerated aging procedure consisting of prolonged forward biasing followed by a dark storage (postbias rest) phase, conducted entirely in the dark. During aging under forward bias, ion migration led to impeded charge transport, macroscopic defect growth, and an adverse response of the cells to short light soaking, all of which recovered in the postbias rest phase, yet resulted in increased recombination due to redistribution of ions. We found that outdoor operation of PSCs in Berlin, Germany, over a 20-month period exhibited similar dynamics, with periods of higher temperature and irradiance (spring-summer) aligning with the forward bias phase and cooler, dimmer periods (fall–winter) aligning with the postbias rest phase. This paves the way for accelerated ageing tests that can mimic ion migration-induced degradation outdoors without requiring an illumination source.

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Published: March 2025

Journal: Solar PRL

Abstract:

A simple diphenylamine-based hole transporting material V1553 was synthesized and incorporated into a perovskite solar cell, which showed remarkable power conversion efficiency close to 23%. The investigated HTM was synthesized via one-step catalyst-free condensation reaction from commercially available and extremely cheap starting reagents, resulting in a fractional cost of the final product compared to the commercial spiro-OMeTAD. This material promises to be a viable p-type organic semiconductor to be employed in the manufacturing of perovskite solar modules.

Cite:

Daskeviciute, S., Zhang, Y., Daskeviciene, M., Rakstys, K., Petrulevicius, J., Jankauskas, V., Getautis, V., & Nazeeruddin, M. K. (2025). Facile and Low-Cost Design Alternative of Spiro-OMeTAD as p-Type Semiconductor for Efficient Perovskite Solar Cells. Solar RRL, 9(8), 2500034. https://doi.org/10.1002/solr.202500034

Published: July 2025

Journal: Advanced Energy Materials

Abstract:

Insights are reported from a 4-year outdoor study in Berlin using encapsulated p–i–n perovskite solar cells with the structure ITO | 2PACz | Cs_0.15FA_0.85PbI_2.55Br_0.45 (bandgap of 1.65 eV) | C₆₀ | SnO₂ | Cu. Peak summer performance showed little to no degradation during the first two summers and only ≈2% absolute drop in outdoor power conversion efficiency from the first to fourth summer. Despite good stability, the devices exhibit significant seasonality, with winter performance up to 30% lower than in summer during the first year, increasing with aging. The factors contributing to this seasonality are separated into four categories: I) solar spectrum, II) device temperature, III) maximum power point tracking losses, and IV) metastability effects. Among these, metastability – particularly light-soaking behavior – is the largest contributing factor that sets perovskite technology apart from conventional photovoltaics. It was found that in cold, low-light winter conditions, voltage gains from light-soaking remain unsaturated, leading to reduced performance. Full saturation requires more than 24 h of continuous illumination, indicating that device performance depends on more than a single diurnal cycle. This comprehensive analysis highlights the complexity of seasonal behavior and the importance of long-term, real-world testing for accurate forecasting of perovskite photovoltaic energy yield.

Cite:

Remec, M., Khenkin, M., Erdil, U., Emery, Q., Paramasivam, G., Unger, E., Schlatmann, R., Albrecht, S., Topič, M., & Ulbrich, C. Seasonality in Perovskite Solar Cells: Insights from 4 Years of Outdoor Data. Advanced Energy Materials, 2501906. https://doi.org/10.1002/aenm.202501906

Published: September 2025

Journal: Solar RRL

Abstract:

Herein, we perform sequential deposition of the organic and inorganic sub-components evaporated from point sources, followed by thermal conversion to yield wide bandgap perovskite films for the application in perovskite/silicon tandem cells. In our approach, uniform formamidinium iodide (FAI) layers with varying thicknesses are first deposited with rotating substrate. We next co-evaporate the inorganic precursors PbI₂, PbBr₂, and CsI onto the FAI layer in a static mode, without substrate rotation, leading to thickness gradients across the substrate, known from single-layer characterization. To promote conversion to α-phase perovskite, another uniform FAI layer is deposited on top, sandwiching the inorganic precursor layer stack. After thermal conversion, we obtain controlled compositional variations of the perovskite layer. Using spatially resolved characterization techniques, the most suitable composition, hence, evaporation rates for the individual inorganic precursors and the best thickness of the FAI sublayer are identified in a time-efficient manner. As a result, an optimized average implied open-circuit voltage, iV_OC, of about 1230 mV and optical bandgap of 1.70 eV, very uniformly distributed over a half M6 wafer area, were achieved for the absorbers when deposited on a self-assembled monolayer. Without any perovskite surface passivation or additional treatment, single-junction devices with an average fill factor of 70% (65%) in reverse (forward) light current–voltage scan and V_OC of 1075 mV were achieved across several batches. Integrating this absorber in tandem cells with a random-pyramid textured bottom-cell led to preliminary cells with efficiencies up to 24%.

Cite:

Mahboubi Soufiani, A., Moumine, H., Wutke, E., Farias Basulto, G. A., de Araujo, W. M. B., Leyden, M., Szot, M., Bertram, T., Škorjanc, V., Harter, A., Severin, S., Roß, M., Mainz, R., Schlatmann, R., Albrecht, S., Stannowski, B., & Kurpiers, J. (2025). Sequentially evaporated wide-bandgap perovskite absorber for large-area and reproducible fabrication of solar cells. Solar RRL, 9(19), Article e2500412. https://doi.org/10.1002/solr.202500412

Published: September 2025

Journal: Nature Communications

Abstract:

Inverted perovskite solar cells face performance limitations due to non-radiative recombination at the perovskite surfaces in devices, including functional layers. Advanced characterization and density functional theory reveal that phosphonic acids passivate perovskite surface defects, while piperazinium chloride mitigates interface recombination by improving energy level alignment, introducing a field effect, and homogenizing the surface. Together, the quasi-Fermi level splitting of the perovskite is homogeneously increased by ca. 100 mV. This enables two-terminal perovskite-on-silicon tandems to achieve a certified open-circuit voltage of 2 V for a 1 cm² device and high performance in excess of 31%. The scalability of the passivation is furthermore demonstrated with homogeneously passivated devices reaching certified efficiencies of 28.9% for an active area of 60 cm².

Cite:

Artuk, K., Oranskaia, A., Turkay, D., Saenz, F., Mensi, M. D., De Bastiani, M., Castro-Méndez, A.-F., Hurni, J., Allebé, C., Othman, M., Champault, L., Kuba, A. G., Levtchenko, A., Jacobs, D. A., Puel, J.-B., Ory, D., Lang, F., Hessler-Wyser, A., Schwingenschlögl, U., Jeangros, Q., Ballif, C., & Wolff, C. M. (2025). 60 cm² perovskite-silicon tandem solar cells with an efficiency of 28.9% by homogeneous passivation. Nature Communications, 16, Article 8672. https://doi.org/10.1038/s41467-025-63673-y

Published: December 2025

Journal: Progress in Photovoltaics

Abstract:

In recent years, photovoltaic (PV) encapsulant films marketed as polyolefins (POs), more specifically as PO elastomers (POEs) and thermoplastic POs (TPOs), have gained significant market share and are projected to become the dominant encapsulation films by 2030. Relative to other industries, there are significant misconceptions about the term PO in the PV industry. Both in the scientific literature as well as in sales and advertising, the terms PO, POE, and TPO are often misused to describe the same type of material with comparable properties, while in reality these may each consist of separate material classes. This paper provides a comprehensive literature and market review, to showcase a broad range of PO and other ethylene copolymer encapsulants from recent studies, and discusses the materials' properties to clarify what constitutes a “polyolefin.” In addition, to promote a clearer comparison of encapsulant properties, we propose a two-dimensional taxonomy to categorize polymers used in module manufacturing, including POs. In terms of improving the reliability of solar PV modules, PO-based encapsulants have several advantages (including lower water uptake and ion diffusion), but might come with disadvantages too, such as a more complex processing and a higher sensitivity to the storage conditions and shelf life. All this might prospectively impact adhesion properties of the encapsulant to other materials' interfaces (glass, cells etc.) and end-product quality. Because the track record of field-deployed PV modules containing PO encapsulants is also limited, we hope to contribute to better material understanding and precision in communication in PV to secure quality.

Cite:

Oreski, G., Barretta, C., Christöfl, P., Gebhardt, P., Weiß, K.-A., Miller, D. C., Uličná, S., Kempe, M., Bruckman, L. S., Virtuani, A., Li, H., Habersberger, B., Munro, J., Proost, K., & Kühne, M. (2025). What is a polyolefin? A critical overview of ethylene copolymers used as solar photovoltaic module encapsulants. Progress in Photovoltaics: Research and Applications. Advance online publication. https://doi.org/10.1002/pip.70038