| 1. |
- Guo, Renjun, et al.
(author)
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Degradation mechanisms of perovskite solar cells under vacuum and one atmosphere of nitrogen
- 2021
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In: Nature Energy. - : Springer Nature. - 2058-7546. ; 6:10, s. 977-
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Journal article (peer-reviewed)abstract
- Extensive studies have focused on improving the operational stability of perovskite solar cells, but few have surveyed the fundamental degradation mechanisms. One aspect overlooked in earlier works is the effect of the atmosphere on device performance during operation. Here we investigate the degradation mechanisms of perovskite solar cells operated under vacuum and under a nitrogen atmosphere using synchrotron radiation-based operando grazing-incidence X-ray scattering methods. Unlike the observations described in previous reports, we find that light-induced phase segregation, lattice shrinkage and morphology deformation occur under vacuum. Under nitrogen, only lattice shrinkage appears during the operation of solar cells, resulting in better device stability. The different behaviour under nitrogen is attributed to a larger energy barrier for lattice distortion and phase segregation. Finally, we find that the migration of excessive PbI2 to the interface between the perovskite and the hole transport layer degrades the performance of devices under vacuum or under nitrogen. Understanding degradation mechanisms in perovskite solar cells is key to their development. Now, Guo et al. show a greater degradation of the perovskite structure and morphology for devices operated under vacuum than under nitrogen.
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| 2. |
- Reb, Lennart K., et al.
(author)
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Space‐ and Post‐Flight Characterizations of Perovskite and Organic Solar Cells
- 2023
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In: Solar RRL. - : Wiley. - 2367-198X. ; 7:9
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Journal article (peer-reviewed)abstract
- Perovskite and organic solar cells are promising for space applications for enabling higher specific powers or alternative deployment systems. However, terrestrial tests can only mimic space conditions to a certain extent. Herein, a detailed analysis of irradiation-dependent photovoltaic parameters of perovskite and organic solar cells exposed to space conditions during a suborbital flight is presented. In orbital altitudes, perovskite and organic solar cells reach power-conversion efficiencies of more than 13% and 6%, respectively. Based on postflight grazing-incidence small-angle and wide-angle X-ray scattering, the active layer morphology and crystalline structure of the returned space solar cells are studied and compared to those of reference solar cells that stayed in an inert atmosphere. Minor changes in the active layer morphology are induced by the sole transport, without causing significant performance loss. For the space solar cells, morphological changes are attributed to the flight experiment that includes rocket launch, spaceflight, and reentry, as well as short-terrestrial environment exposure before and after launch. In contrast, no significant changes to the crystalline phase are observed. The notable performance during flight and high active layer stability, especially of perovskite solar cells, are promising results for further steps toward an orbital demonstration.
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| 3. |
- Reus, Manuel A., et al.
(author)
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INSIGHT: in situ heuristic tool for the efficient reduction of grazing-incidence X-ray scattering data
- 2024
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In: Journal of applied crystallography. - : International Union of Crystallography (IUCr). - 0021-8898 .- 1600-5767. ; 57, s. 509-528
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Journal article (peer-reviewed)abstract
- INSIGHT is a Python-based software tool for processing and reducing 2D grazing-incidence wide- and small-angle X-ray scattering (GIWAXS/GISAXS) data. It offers the geometric transformation of the 2D GIWAXS/GISAXS detector image to reciprocal space, including vectorized and parallelized pixelwise intensity correction calculations. An explicit focus on efficient data management and batch processing enables full control of large time-resolved synchrotron and laboratory data sets for a detailed analysis of kinetic GIWAXS/ GISAXS studies of thin films. It processes data acquired with arbitrarily rotated detectors and performs vertical, horizontal, azimuthal and radial cuts in reciprocal space. It further allows crystallographic indexing and GIWAXS pattern simulation, and provides various plotting and export functionalities. Customized scripting offers a one-step solution to reduce, process, analyze and export findings of large in situ and operando data sets.
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| 4. |
- Reus, Manuel A., et al.
(author)
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Modular slot-die coater for in situ grazing-incidence x-ray scattering experiments on thin films
- 2024
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In: Review of Scientific Instruments. - : AIP Publishing. - 0034-6748 .- 1089-7623. ; 95:4
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Journal article (peer-reviewed)abstract
- Multimodal in situ experiments during slot-die coating of thin films pioneer the way to kinetic studies on thin-film formation. They establish a powerful tool to understand and optimize the formation and properties of thin-film devices, e.g., solar cells, sensors, or LED films. Thin-film research benefits from time-resolved grazing-incidence wide- and small-angle x-ray scattering (GIWAXS/GISAXS) with a sub-second resolution to reveal the evolution of crystal structure, texture, and morphology during the deposition process. Simultaneously investigating optical properties by in situ photoluminescence measurements complements in-depth kinetic studies focusing on a comprehensive understanding of the triangular interdependency of processing, structure, and function for a roll-to-roll compatible, scalable thin-film deposition process. Here, we introduce a modular slot-die coater specially designed for in situ GIWAXS/GISAXS measurements and applicable to various ink systems. With a design for quick assembly, the slot-die coater permits the reproducible and comparable fabrication of thin films in the lab and at the synchrotron using the very same hardware components, as demonstrated in this work by experiments performed at Deutsches Elektronen-Synchrotron (DESY). Simultaneous to GIWAXS/GISAXS, photoluminescence measurements probe optoelectronic properties in situ during thin-film formation. An environmental chamber allows to control the atmosphere inside the coater. Modular construction and lightweight design make the coater mobile, easy to transport, quickly extendable, and adaptable to new beamline environments.
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| 5. |
- Tu, Suo, et al.
(author)
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Improvement of the thermoelectric properties of PEDOT:PSS films via DMSO addition and DMSO/salt post-treatment resolved from a fundamental view
- 2022
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In: Chemical Engineering Journal. - : Elsevier BV. - 1385-8947 .- 1873-3212. ; 429
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Journal article (peer-reviewed)abstract
- The combination of dimethyl sulfoxide (DMSO)-solvent doping and physical-chemical DMSO/salt de-doping in a sequence has been used to improve the thermoelectric (TE) properties of poly(3,4-ethylenedioxythiophene):poly (4-styrenesulfonate) (PEDOT:PSS) films. A high power factor of ca.105.2 mu W m(-1) K-2 has been achieved for the PEDOT:PSS film after post-treatment with 10 % sodium sulfite (Na2SO3) in the DMSO/salt mixture (v/v), outperforming sodium bicarbonate (NaHCO3). The initial DMSO-doping treatment induces a distinct phase separation by facilitating the aggregation of the PEDOT molecules. At the same time, the subsequent DMSO/salt dedoping post-treatment strengthens the selective removal of the surplus non-conductive PSS chains. Substantial alterations in the oxidation level, chain conformations, PEDOT crystallites and their preferential orientation are observed upon treatment on the molecular level. At the mesoscale level, the purification and densification of PEDOT-rich domains enable the realization of inter-grain coupling by the formation of the electronically well-percolated network. Thereby, both electrical conductivity and Seebeck coefficient are optimized.
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