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The development and scale‐up of lithium‐ion battery (LIB) production for a sustainable energy supply is advancing very rapidly and in versatile directions. Manufacturing processes and production steps are constantly developed and optimized to improve production efficiency. To integrate new machinery into a production line while conforming to the DIN EN ISO 9001 standards of certification, it is necessary to define the procedures for assuring product quality. Herein, a quality assurance concept is designed for an innovative flexible stacking process currently under development. Critical sources of errors are identified by employing the failure process matrix approach. On this basis, it is described how these errors are either avoided by suitable design of the machine components and its control or by which inspection technology is integrated to detect defective intermediate products. In the resulting quality assurance concept, a digital twin of the stacking machine is employed to constantly surveil process and product properties and also to facilitate the change of the produced products on the machine. Evaluating the quality management already in the design phase of the machine saves resources and enables a deeper understanding of the stacking process. [ABSTRACT FROM AUTHOR]

Light‐harvesting devices made from lead sulfide quantum dot (QD) absorbers are one of the many promising technologies of third‐generation photovoltaics. Their simple, solution‐based fabrication, together with a highly tunable and broad light absorption makes their application in newly developed solar cells, particularly promising. In order to yield devices with reduced voltage and current losses, PbS QDs need to have strategically passivated surfaces, most commonly achieved through lead iodide and bromide passivation. The interdot spacing is then predominantly filled with residual amorphous lead halide species that remain from the ligand exchange, thus hindering efficient charge transport and reducing device stability. Herein, it is demonstrated that a post‐treatment by iodide‐based 2‐phenylethlyammonium salts and intermediate 2D perovskite formation can be used to manage the lead halide excess in the PbS QD active layer. This treatment results in improved device performance and increased shelf‐life stability, demonstrating the importance of interdot spacing management in PbS QD photovoltaics. [ABSTRACT FROM AUTHOR]

Thin‐film deposition by thermal evaporation offers many advantages, yet in the field of perovskite photovoltaics solution‐processed devices significantly outperform those fabricated by thermal evaporation. Here, high‐quality γ‐CsPbI3 perovskite layers by coevaporation of PbI2 and CsI with a small amount of phenylethylammonium iodide (PEAI) are deposited. It is demonstrated that the addition of PEAI into the perovskite layers leads to a preferred crystal orientation and a far improved microstructure, with columnar domains that protrude throughout the film's thickness. This is accompanied by a reduced density of defects as evidenced by the increase in photoluminescence and decrease in Urbach energy as compared to reference CsPbI3 films. Photovoltaic devices based on the PEAI containing perovskite layers reach up to 15% in power conversion efficiency, thus surpassing not only the performance of reference CsPbI3 devices, but also that of most solution‐processed PEAI containing inorganic CsPbX3 (X = Cl, Br, I) perovskite solar cells. Importantly, encapsulated thermally evaporated perovskite devices maintain their performance for over 215 days, demonstrating the stabilizing effect of PEAI on thermally evaporated CsPbI3. [ABSTRACT FROM AUTHOR]

Colloidal quantum dot solar cells (QDSCs) are promising candidates amongst third generation photovoltaics due to their bandgap tunability, facile low‐temperature ink processing, strong visible‐to‐infrared absorption, and potential for multiple‐exciton generation. An unprecedented increase in power conversion efficiency is reported for different types of QDSCs in the last few years, making them appealing for large‐scale fabrication. The stability of QDSCs, however, still remains inadequate for industrial application, especially when they are operated under a sun‐like illumination in an ambient atmosphere. This review focuses on three classes of QDs (lead chalcogenides, lead halide perovskites, and lead‐free QDs) and considers the current understanding of their degradation mechanisms. For each material class, strategies for stability improvement are discussed, both from materials science and device engineering perspectives. This paper concludes by suggesting a methodology for characterizing the QDSCs' stability which would standardize the results obtained by researchers worldwide. [ABSTRACT FROM AUTHOR]

This paper investigates the impact of microstructure on the degradation rate of methylammonium lead triiodide (MAPbI3) perovskite films upon exposure to light and oxygen. By comparing the oxygen induced degradation of perovskite films of different microstructure-fabricated using either a lead acetate trihydrate precursor or a solvent engineering technique-it is demonstrated that films with larger and more uniform grains and better electronic quality show a significantly reduced degradation compared to films with smaller, more irregular grains. The effect of degradation on the optical, compositional, and microstructural properties of the perovskite layers is characterized and it is demonstrated that oxygen induced degradation is initiated at the layer surface and grain boundaries. It is found that under illumination, irreversible degradation can occur at oxygen levels as low as 1%, suggesting that degradation can commence already during the device fabrication stage. Finally, this work establishes that improved thin-film microstructure, with large uniform grains and a low density of defects, is a prerequisite for enhanced stability necessary in order to make MAPbI3 a promising long lived and low cost alternative for future photovoltaic applications. [ABSTRACT FROM AUTHOR]

Perovskite Photovoltaic Devices: Enhancing the Open-Circuit Voltage of Perovskite Solar Cells by up to 120 mV Using -Extended Phosphoniumfluorene Electrolytes as Hole Blocking Layers (Adv. In article number 1901257, Yana Vaynzof and co-workers introduce -extended phosphoniumfluorene electrolytes as hole-blocking layers in planar perovskite solar cells. Electrolytes, hole-blocking layers, interfacial engineering, perovskite solar cells. [Extracted from the article]

Four π‐extended phosphoniumfluorene electrolytes (π‐PFEs) are introduced as hole‐blocking layers (HBL) in inverted architecture planar perovskite solar cells with the structure of ITO/PEDOT:PSS/MAPbI3/PCBM/HBL/Ag. The deep‐lying highest occupied molecular orbital energy level of the π‐PFEs effectively blocks holes, decreasing contact recombination. It is demonstrated that the incorporation of π‐PFEs introduces a dipole moment at the PCBM/Ag interface, resulting in significant enhancement of the built‐in potential of the device. This enhancement results in an increase in the open‐circuit voltage of the device by up to 120 mV, when compared to the commonly used bathocuproine HBL. The results are confirmed both experimentally and by numerical simulation. This work demonstrates that interfacial engineering of the transport layer/contact interface by small molecule electrolytes is a promising route to suppress nonradiative recombination in perovskite devices and compensates for a nonideal energetic alignment at the hole‐transport layer/perovskite interface. [ABSTRACT FROM AUTHOR]

In article number 1700977, Yana Vaynzof and co‐workers investigate how the MAPbI3 perovskite layer microstructure is affecting its stability upon exposure to oxygen and light. The authors show that the degradation process is initiated at the grain boundaries, demonstrating that devices whose active layer consists of larger, more uniform grains exhibit enhanced photovoltaic stability. [ABSTRACT FROM AUTHOR]