@article{KafedjiskaLeCorreKoebleretal., author = {Kafedjiska, Ivona and Le Corre, Vincent M. and K{\"o}bler, Hans and Levine, Igal and Schlatmann, Rutger and Lauermann, Iver}, title = {Investigation of interfacial charge-carrier dynamics, degradation, and recombination mechanisms in single-junction perovskite solar cells with NiOx and SAM hole-transporting layers via steady-state drift-diffusion model simulations}, series = {Sustainable Energy \& Fuels}, volume = {10}, journal = {Sustainable Energy \& Fuels}, number = {4}, publisher = {The Royal Society of Chemistry}, issn = {2398-4902}, doi = {10.1039/d5se00474h}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:523-22345}, pages = {1174 -- 1191}, abstract = {We investigate the stability and the degradation pathways in single-junction perovskite solar cells with four varying hole-transporting layers (HTLs): pure nickel oxide (NiOx) and copper-doped (NiOx:Cu), with or without self-assembled monolayer (SAM) surface passivation. The cells are aged in a continuous MPP-tracking set-up in a nitrogen environment at 25 °C and the JV curves prior to and after the aging are fitted via drift-diffusion simulations. By using a set of experimentally-measured input parameters and correlating the results from the experiments with the simulations, we are able to test the reliability of the model and then extract important information about the interfacial charge-carrier dynamics, recombination, and degradation mechanisms in the solar cells. We find that NiOx induces severe electron trapping and poor band alignment at the NiOx-perovskite interface, thereby leading to the highest quasi-Fermi level splitting to open-circuit voltage (QFLS-Voc) offset among all the HTLs. As the cells age, the density of bulk traps when NiOx, NiOx:Cu, and NiOx:Cu + SAM are used increases by factors of 36, 3, and 8, respectively, while for NiOx + SAM it remains unchanged. For all of the HTLs, the non-radiative Shockley-Read-Hall (SRH) recombination via surface traps is the dominant recombination mechanism, as it is around 2-3 orders of magnitude higher than the direct or bulk-SRH recombination pathway. Additionally, NiOx exhibits an around 2 orders of magnitude higher rate of SRH interfacial recombination compared to the other three HTLs. However, as the cells age, the rate of the interface SRH recombination remains relatively stable, but the bulk SRH recombination increases by an order of magnitude in all cells, indicating that the degradation of the cells is directly proportional to the increase of the trap-assisted recombination in the perovskite bulk and its degradation. Finally, we investigate the correlation between the hysteresis factor (HF) and the ion concentration. We find that the devices with NiOx have the highest HF and the highest negative-ion concentration, in good agreement with the finding of electron trapping and the highest trap-assisted recombination rate for the NiOx samples. Combining all of this information, we can explain why NiOx is the least stable HTL among all the HTLs (15\% loss in the initial PCE) and how its stability can be improved with Cu doping (8\% loss in the initial PCE) and, to an extent, with SAM passivation (around 11\% loss in the initial PCE).}, language = {en} } @article{BergnerOrthMeissneretal., author = {Bergner, Joseph and Orth, Nico and Meissner, Lucas and Quaschning, Volker}, title = {Solar Charging—Lessons Learned from Field Observation}, series = {World Electric Vehicle Journal}, volume = {17}, journal = {World Electric Vehicle Journal}, number = {2}, editor = {Sierpiński, Grzegorz}, publisher = {MDPI}, issn = {2032-6653}, doi = {10.3390/wevj17020069}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:523-22325}, abstract = {Although the combination of solar power and electric vehicles is widely considered beneficial, practical applications reveal substantial variance. To determine the proportion of solar energy used for charging and to identify the main drivers of a high solar share, a dataset containing measured 5 min energy time series of 725 households with PV and EVs was analyzed. In the existing literature, this represents a novelty, as most studies in this field are simulation-based, rely on synthetic profiles, use lower time resolutions, or are based on questionnaires. The share of solar energy used for EV charging is highly dispersed and varies by about ±40\% around a median of 60\%. The analysis shows that clustering by preferred charging times has strong explanatory potential: at the median, EVs charged predominantly during the daytime achieve a solar share that is more than 40\% higher than those charged in the evening. In the latter case, home battery storage increases the solar share by an average of 20 percentage points. A similar magnitude of a 25-percentage-point increase could be reached with solar surplus charging compared to uncontrolled charging. On average, households with PV, battery, and EVs cover more than 56\% of their total demand with self-generated solar energy; with solar-adapted charging, median values exceed 77\%. If a heat pump is used on site, the self-sufficiency decreases but can still reach median values above 45\% and up to 61\% for optimized households.}, subject = {Consumer behavior}, language = {en} } @masterthesis{Bartkowiak, type = {Bachelor Thesis}, author = {Bartkowiak, Jakub}, title = {Labortechnischer Vergleich sowie Bewertung der Schalterversagerschutz-Reststromerkennung verschiedener Schutzger{\"a}te}, school = {Hochschule f{\"u}r Technik und Wirtschaft Berlin}, pages = {33}, abstract = {Schutzrelais detektieren Fehlerstr{\"o}me wie Kurzschl{\"u}sse oder {\"U}berlast innerhalb von Millisekunden und trennen selektiv den betroffenen Netzabschnitt ab, um Sch{\"a}den und großfl{\"a}chige Ausf{\"a}lle zu verhindern. Zur Erh{\"o}hung der Betriebssicherheit wird das Schutzkonzept redundant ausgelegt. Eine wesentliche Reservefunktion bildet der Schalterversagerschutz (SVS), der ein Versagen des Leistungsschalters erkennt und bei Bedarf einen {\"u}bergeordneten Schutzmechanismus ansteuert. Durch Ausschaltvorg{\"a}nge k{\"o}nnen jedoch Reststr{\"o}me entstehen, wodurch f{\"a}lschliche SVS-Ausl{\"o}sungen hervorgerufen werden. Ziel dieser Arbeit ist die labortechnische Untersuchung des Verhaltens der Schutzger{\"a}te 7SJ511, DS6, PS441 und 7SX85, um die SVS-Parameter optimal einstellen zu k{\"o}nnen.}, language = {de} } @masterthesis{Andrean, type = {Bachelor Thesis}, author = {Andrean, Verio}, title = {Entwicklung und Charakterisierung nachhaltiger Akustik-materialien f{\"u}r den passiven Schallschutz in Geb{\"a}uden}, school = {Hochschule f{\"u}r Technik und Wirtschaft Berlin}, pages = {85}, abstract = {Die vorliegende Arbeit untersucht das {\"o}kologische und funktionale Potenzial neuartiger plattenf{\"o}rmiger akustischer Metamaterialien (PAM) im Vergleich zu einem markt{\"u}blichen Referenzprodukt (Knauf Silentboard). Auf Grundlage einer transparenten Methodik - bestehend aus indikatorbasierter {\"O}kobilanzierung, Min-Max-Normalisierung und vergleichender Darstellung - wurden drei PAM-Konzepte hinsichtlich ihrer Umweltwirkungen (Module A1-A3) sowie ihrer akustischen Leistungsf{\"a}higkeit bewertet. Die Ergebnisse zeigen, dass insbesondere PAM 3 mit einem normierten Umwelt-Score von 0,80 deutlich bessere {\"o}kologische Eigenschaften aufweist als das Silentboard (0,59). PAM 2 und PAM 1 erreichten moderate Werte, zeigten aber ebenfalls einzelne {\"o}kologische Vorteile. Die akustische Bewertung ergab hingegen, dass alle PAM-Konzepte mit einem bewerteten Schalld{\"a}mmmaß von 18 dB deutlich unter dem Referenzprodukt (32 dB) liegen. Damit kann Hypothese 1 best{\"a}tigt, Hypothese 2 jedoch nicht unterst{\"u}tzt werden. Die eingesetzte Normalisierungsmethode erwies sich als geeignet, heterogene Indikatoren vergleichbar darzustellen (Best{\"a}tigung von Hypothese 3). Insgesamt zeigt die Arbeit, dass PAMs weniger als Substitut, sondern vielmehr als funktional-{\"o}kologische Erg{\"a}nzung konventioneller Baustoffe geeignet sind. Abschließend werden Perspektiven f{\"u}r biobasierte PAMs, hybride Konstruktionen sowie die Erweiterung um LCC- und Social-LCA-Analysen aufgezeigt.}, language = {de} } @article{WinartoSutterTockhornetal., author = {Winarto, Hanifah and Sutter, Johannes and Tockhorn, Philipp and Škorjanc, Viktor and Patil, Pramila and Berwig, Sebastian and Zimmermann, Lea and Mart{\´i}nez-Denegri, Guillermo and Albrecht, Steve and Becker, Christiane}, title = {Periodic Inverted Micropyramids for Optically Optimized Fully Textured Solution-Processed Perovskite Solar Cells}, series = {Solar RRL}, volume = {9}, journal = {Solar RRL}, number = {23}, publisher = {Wiley}, issn = {2367-198X}, doi = {10.1002/solr.202500613}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:523-22175}, pages = {10}, abstract = {Optical performance of perovskite-based solar cells can be enhanced by utilizing fully textured interfaces. However, solution processing of perovskite films on textured surfaces is a nonstraightforward and challenging process, particularly if optically most efficient micrometer-sized textures are used. In this work, we present fully textured solution-processed perovskite solar cells on periodic inverted micropyramids. The textures have a period of 4 μm with varying pyramid depths and are fabricated by wet-chemical etching of silicon with subsequent replication on glass substrates using nanoimprint lithography. Inverted pyramids are shown to enable low reflectance similar to random micropyramids on silicon. Additionally, they are able to confine perovskite precursor solution within its structure during spin coating, resulting in a conformal, fully textured perovskite film. We demonstrate that the resulting fully textured single-junction perovskite solar cells feature a reduced reflection loss of up to 1.2 mA/cm 2 in short-circuit current density. Moreover, we observe that the amount of lead iodide in the perovskite precursor solution crucially impacts growth and nonradiative recombination losses of the fully textured perovskite solar cells on inverted micropyramids. Finally, we prove the versatility of our approach by also demonstrating conformal coating with slot-die coating, which is a scalable process considered for industrial application.}, subject = {Solar cells}, language = {en} } @article{Farias‐BasultoKafedjiskaBertrametal., author = {Farias-Basulto, Guillermo and Kafedjiska, Ivona and Bertram, Tobias and Riedel, Maximilian and Emery, Quiterie and Remec, Marko and Graniero, Paolo and Khenkin, Mark and Kaufmann, Christian A. and Lauermann, Iver and Klenk, Reiner and Schlatmann, Rutger and Ulbrich, Carolin}, title = {Perovskite-CIGSe Tandem Solar Cell: Over One Year of Outdoor Monitoring}, series = {Advanced Energy and Sustainability Research}, volume = {6}, journal = {Advanced Energy and Sustainability Research}, number = {12}, issn = {2699-9412}, doi = {10.1002/aesr.202500162}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:523-22159}, pages = {11}, abstract = {Tandem solar cells can surpass the limitations of single-junction devices, promising increased performance due to lower thermalization losses. Even though many research and industrial upscaling efforts are based on perovskite-Si tandems, all-thin-film photovoltaic (PV) devices, for instance with chalcopyrite (CIGSe) and perovskite, can offer many advantages such as significant cost and material savings and access to niche markets like building integrated- and flexible PV. However, long-term stability and outdoor performance of perovskite-based tandem devices is to this day challenging. This work presents the first data analysis of year-round outdoor measurements (mpp-tracked) of a perovskite-chalcopyrite tandem device with a starting efficiency of about 23.14\% before encapsulation. The maximum outdoor performance of the tandem device changed during the period of observation, reaching the peak performance in April and then decreased due to the device degradation. At its maximum outdoor performance, the tandem could reach up to 68\% higher instantaneous power output, relative to its single-junction reference (CIGSe-SJ). In addition, a quantitative time series performance analysis, exemplary qualitative imaging characterization of the tandem before and after outdoor exposure, is shown. Finally, the possibility of predicting the immediate performance of an all-thin-film tandem is verified by using a multiple linear regression model with accuracies generally exceeding 90\%.}, subject = {Machine learning}, language = {en} } @misc{Eisenreich, type = {Master Thesis}, author = {Eisenreich, Florian Gabriel}, title = {Optimierung eines Versatile Video Decoders f{\"u}r ARM Architekturen}, school = {Hochschule f{\"u}r Technik und Wirtschaft Berlin}, pages = {79}, abstract = {The daily consumption of video content has become indispensable for numerous people. To make this everyday experience possible for so many individuals imultaneously, video content must be compressed. Uncompressed videos are large files and require more band- width for transmission. Compression, in combination with advances in data transmission, enables the vast amount of video content available on the internet today. Compression is achieved using so-called codecs. A video is available encoded and is decoded on the recipient's end to be viewed. Processors and Systems-on-Chip are getting increasingly more powerful and the consumption of video content is shifting towards mobile devices, such as smartphones and tablets. These mobile devices typically rely on the Arm architecture developed by ARM Limited. The recent IPO and the keen interest from both institutional and individual investors underscore the significance of ARM as well as its technologies. In this work, a video decoder implementing the Versatile Video Codec (VVC) released in 2020 is optimized for the Arm architecture. The decoder to be optimized is the publicly available Fraunhofer Versatile Video Decoder (VVdeC) from the Fraunhofer Heinrich Hertz Institut. The optimization is done using Single Instruction Multiple Data (SIMD). The study compares the automatic translation of non-architectural SIMD functions with manual optimization. The research demonstrates that manual optimization can yield substantial speed improvements. However, it also highlights that in many cases, automatic replacement is a viable option that saves programming effort. By optimizing individual functions, significant overall program acceleration can be achieved. For readers that wish to apply the work on their own optimization a quick guide is provided in the last chapter of the thesis.}, language = {de} } @misc{Bode, type = {Master Thesis}, author = {Bode, Max Julius}, title = {Verbesserung der Aufl{\"o}sung in koh{\"a}renten FMCW-LiDAR Systemen}, school = {Hochschule f{\"u}r Technik und Wirtschaft Berlin}, pages = {66}, abstract = {The paper at hand considers the effects of changes in temperature on two key performance indicators of directly modulated FMCW-LiDAR-systems: Dynamic (modulation) bandwidth and peak-width of the spectrum of intermediate frequency. To begin with, the system is characterized under steady-state conditions at different temperature points in a practical temperature interval. This measurement is referred to as static measurement. A temperature dependence of the dynamic bandwidth is derived, as well as an increase in peak-width with increasing temperature. This characterization is also used to calibrate the difference-length of the system. It is shown, that this calibration length is not dependent on temperature. The same measurement is repeated for the same temperature points but without allowing the system to settle. This measurement is referred to as dynamic measurement. It is shown that there are no practical differences between static and dynamic changes in temperature. The measurements are repeated again while using a pre-distortion algorithm to mitigate nonlinear items resulting from a non-linear response of the laser diode to its linear modulation current. It is shown, that the pre-distortion algorithm lowers the peak-width significantly, thus increasing measurement accuracy. Additionally an equi-phase resampling technique is applied as an alternative to the pre-distortion to evaluate its temperature dependance. It is shown that both methods are independent from temperature. Resampling has been proven to remove all non-linear effects on the resulting intermediate frequency, thus lowering its spectral peak-width to almost a Dirac-impulse. However, the scientific consensus so far has been, that pre-distortion is temperature dependant and thus a temperature stabilization of the laser diode is required. Lastly the non-linearity of the instantaneous frequency response is evaluated at different temperature points and the RMSE to a reference polynomial is used as a FoM to evaluate the residual difference. This is called the non-linearity and is theoretically tied to the peak-width via a Fourier-transform. It is shown, that the non-linearity is temperature dependant and also lowered via pre-distortion and mitigated via the resampling technique. Based on the results of this paper, a compensation method for the temperature dependance of the dynamic bandwidth is proposed to correct for a resulting error in intermediate frequency and thus distance measurement.}, language = {de} } @misc{Arslan, type = {Master Thesis}, author = {Arslan, Mahir}, title = {Human-Building-Interaction zur Unterst{\"u}tzung bei manueller Fensterl{\"u}ftung}, school = {Hochschule f{\"u}r Technik und Wirtschaft Berlin}, pages = {108}, abstract = {Diese Masterarbeit besch{\"a}ftigt sich mit der Entwicklung eines innovativen Systems der Mensch-Geb{\"a}ude-Interaktion (MGI), zur {\"U}berwachung und Verbesserung der Luftqualit{\"a}t in Innenr{\"a}umen. Angesichts der wachsenden Bedenken hinsichtlich der Luftqualit{\"a}t und deren Auswirkungen auf Gesundheit und Wohlbefinden, insbesondere in Bildungseinrichtungen und B{\"u}ros, zielt dieses Projekt darauf ab, ein intelligentes benutzerfreundliches System zu entwickeln, das eine effektive {\"U}berwachung der Raumluft erm{\"o}glicht und darauf basierend L{\"u}ftungsempfehlungen ausgibt. Der Kern des Systems besteht aus einem zentralen Hub und mehreren autarken Sonden, die mit Sensoren f{\"u}r Temperatur, relative Feuchtigkeit, CO2, Feinstaub und VOC ausgestattet sind. Durch die Anwendung von IoT-Technologien und die Integration von Node-Red als Online-Softwareschnittstelle, kombiniert mit einer Cloud-Datenbank, erm{\"o}glicht das System eine effiziente Datensammlung sowie Datenanalyse und f{\"o}rdert ein bewusstes L{\"u}ftungsverhalten. Die Ergebnisse zeigen, dass das MGI-System erfolgreich die Luftqualit{\"a}t {\"u}berwacht und dadurch das Bewusstsein f{\"u}r eine gesunde Raumluft steigern kann. Dar{\"u}ber hinaus bietet die Arbeit einen Ausblick auf m{\"o}gliche zuk{\"u}nftige Erweiterungen zur Erweiterung der Software-Funktionalit{\"a}ten f{\"u}r einen realen Einsatz, der Entwicklung eines Touchscreens f{\"u}r die Nutzerinteraktion oder M{\"o}glichkeiten f{\"u}r vertiefte Datenanalysen. Insgesamt liefert diese Arbeit einen wertvollen Beitrag zur F{\"o}rderung der technologischen Innovationen im Forschungsfeld der Mensch-Geb{\"a}ude-Interaktion und der Raumluftqualit{\"a}t.}, language = {de} } @misc{Borchadt, type = {Master Thesis}, author = {Borchadt, Christopher}, title = {Implementierung eines N-Version Systems zur Schienenerkennung auf Basis neuronaler Netze in ROS}, school = {Hochschule f{\"u}r Technik und Wirtschaft Berlin}, pages = {113}, abstract = {Trotz großer Fortschritte auf dem Gebiet der Datenverarbeitung mit neuronalen Netzen werden bis heute nur wenige davon in sicherheitskritischen Systemen eingesetzt. Der Grund daf{\"u}r liegt darin, dass neuronale Netze keine deterministischen Aussagen produzieren. Vielmehr wird eine Aussagesicherheit generiert, die angibt wie selbstsicher das Netz mit dessen Vorhersage ist. Diese Aussagesicherheit, auch Konfdienz genannt, ist jedoch von mehreren Faktoren wie dem Training oder den Trainingsdaten abh{\"a}ngig und daher alleinestehend in sicherheitskritischen Anwendungen nicht zuverl{\"a}ssig genug. Ein Ansatz zur Erh{\"o}hung der Sicherheit von Aussagen ist die Verwendung von N-Version Systemen f{\"u}r neuronale Netze. In ihnen werden Date parallel durch mehrere Modelle verarbeitet, deren Vorhersagen anschließend zu einer verbesserten Vorhersage mit besserer Konfidenz zusammengef{\"u}hrt werden. In der Arbeit wird ein solches N-Version System innerhalb des ROS2-Frameworks implementiert. Das N-Version System wird in der Implementierung eines Systems zur Hinderniserkennung von Z{\"u}gen betrachtet. Dieses System wird Railroad Obstacle Detection System, oder kurz ROD-System genannt. F{\"u}r das ROD-System wird in dieser Arbeit die Grundstruktur aufgebaut. Hierzu werden zun{\"a}chst der Anforderungsbereich und die Struktur des Systems definiert und anschließend innerhalb von ROS2 umgesetzt. Die Hinderniserkennung wird in Teilaufgaben zerteilt, welche in Subsysteme gel{\"o}st werden. Eines der Subsysteme hat dabei die Aufgabe die Schienen vor dem Zug zu erkennen. Dieses System wird durch ein N-Version System umgesetzt. Die Schienenerkennung wird dabei durch bin{\"a}re Segmentierung von Bilddaten realisiert. Das N-Version System wird anschließend als ein System mit einem Eingang und drei Modellen instanziiert und getestet. Dabei wird gepr{\"u}ft, ob das N-Version System die Vorhersagequalit{\"a}t und die Konfidenz im Vergleich zu den verwendeten Modellen verbessert. Es werden dazu verschiedene Methoden zur Fusion der Vorhersagen sowie der Konfidenzberechnung getestet. Neue Methoden wie die Fusion der Vorhersagen durch Aktivierungsfunktionen werden mit Algorithmen aus vorangegangenen Arbeiten verglichen. Dar{\"u}ber hinaus wird das zeitliche Verhalten des instanziierten Systems aufgenommen. Es werden dazu zwei Varianten zur Synchronisierung der Vorhersagen definiert und umgesetzt. Beide Methoden werden miteinander verglichen und entsprechenden Anwendungsf{\"a}llen zugeordnet. Abschließend wird anhand eines Beispiels der Konfidenzschwellwert γ f{\"u}r das N-Version System ausgelegt und die passende Methode zur Sychronisierung ausgew{\"a}hlt.}, language = {de} }