Bacterial cell wall peptidoglycan is essential, maintaining both cellular integrity and morphology, in the face of internal turgor pressure. Peptidoglycan synthesis is important, as it is targeted by cell wall antibiotics, including methicillin and vancomycin. Here, we have used the major human pathogen Staphylococcus aureus to elucidate both the cell wall dynamic processes essential for growth (life) and the bactericidal effects of cell wall antibiotics (death) based on the principle of coordinated peptidoglycan synthesis and hydrolysis. The death of S. aureus due to depletion of the essential, two-component and positive regulatory system for peptidoglycan hydrolase activity (WalKR) is prevented by addition of otherwise bactericidal cell wall antibiotics, resulting in stasis. In contrast, cell wall antibiotics kill via the activity of peptidoglycan hydrolases in the absence of concomitant synthesis. Both methicillin and vancomycin treatment lead to the appearance of perforating holes throughout the cell wall due to peptidoglycan hydrolases. Methicillin alone also results in plasmolysis and misshapen septa with the involvement of the major peptidoglycan hydrolase Atl, a process that is inhibited by vancomycin. The bactericidal effect of vancomycin involves the peptidoglycan hydrolase SagB. In the presence of cell wall antibiotics, the inhibition of peptidoglycan hydrolase activity using the inhibitor complestatin results in reduced killing, while, conversely, the deregulation of hydrolase activity via loss of wall teichoic acids increases the death rate. For S. aureus, the independent regulation of cell wall synthesis and hydrolysis can lead to cell growth, death, or stasis, with implications for the development of new control regimes for this important pathogen.

Self-assembled monolayers (SAMs) are becoming widely utilized as hole-selective layers in high-performance p-i-n architecture perovskite solar cells. Ultrasonic spray coating and airbrush coating are demonstrated here as effective methods to deposit MeO-2PACz; a carbazole-based SAM. Potential dewetting of hybrid perovskite precursor solutions from this layer is overcome using optimized solvent rinsing protocols. The use of air-knife gas-quenching is then explored to rapidly remove the volatile solvent from an MAPbI 3 precursor film spray-coated onto an MeO-2PACz SAM, allowing fabrication of p-i-n devices with power conversion efficiencies in excess of 20%, with all other layers thermally evaporated. This combination of deposition techniques is consistent with a rapid, roll-to-roll manufacturing process for the fabrication of large-area solar cells.

Organic-inorganic metal halide perovskites are rapidly approaching state-of-the-art silicon solar cells, with bestperforming devices now reaching power conversion efficiencies (PCEs) of 25.7%. [1] Although stability remains a challenge for perovskite solar cells (PSCs), their solution-processability represents a major advantage. Techniques such as blade coating, [2] slot-die coating, [3] and spray coating [4] are compatible with roll-to-roll (R2R) processing, which-in principleshould allow much higher throughput speeds than existing silicon solar technologies. However, the lengthy annealing times used to crystallize the perovskite active layer reduce the maximum theoretical web speeds that could be achieved in a practical manufacture process.In 2020, Rolston et al. demonstrated the highest coating speeds of any scalable PSC processing technologies, achieving production speeds of >12 m min −1 . [5] Spray coating was combined with an atmospheric plasma postprocessing route, [6] creating PSC devices and modules with a PCE of 18% and 15.5%, respectively. Critically, these were fabricated without annealing the perovskite layer. At these speeds, the module cost is expected to be fully competitive with Si. [7] In contrast, the calculated throughput rate for spin-coated PSCs incorporating a 10-min anneal is just 0.017 m min −1 ; a rate prohibitive for commercialization. Furthermore, high temperature processing steps increase device manufacturing costs through increased utility costs and reduced throughput. [8] High process temperatures are also incompatible with many sensitive flexible (polymeric) substrates that are expected to be important in "Internet of Things" applications. [9,10] This growing market is expected to reduce the initial investment and barrier to market entry for perovskites by an order of magnitude. [11] Many approaches to create "annealing-free" PSCs have been demonstrated. For example, thermal evaporation of the perovskite layer without any post-annealing treatments can be used to realize devices having reasonable PCEs of up to 15.7%. [12,13] Zhou et al. demonstrated devices with a PCE of 15.7% for MAPbI 3 (where MA is methylammonium) films grown via electrochemical fabrication. [14] The use of antisolvent High temperature post-deposition annealing of hybrid lead halide perovskite thin films-typically lasting at least 10 min-dramatically limits the maximum roll-to-roll coating speed, which determines solar module manufacturing costs. While several approaches for "annealing-free" perovskite solar cells (PSCs) have been demonstrated, many are of limited feasibility for scalable fabrication. Here, this work has solvent-engineered a high vapor pressure solvent mixture of 2-methoxy ethanol and tetrahydrofuran to deposit highly crystalline perovskite thin-films at room temperature using gas-quenching to remove the volatile solvents. Using this approach, this work demonstrates p-i-n devices with an annealing-free MAPbI 3 perovskite layer achieving stabilized power conversion efficiencies (PCEs) of up to 1...

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Tailoring the solution chemistry of metal halide perovskites requires a detailed understanding of precursor aggregation and coordination. In this work, we use various scattering techniques, including dynamic light scattering (DLS), small angle neutron scattering (SANS), and spin–echo SANS (SESANS) to probe the nanostructures from 1 nm to 10 μm within two different lead-halide perovskite solution inks (MAPbI 3 and a triple-cation mixed-halide perovskite). We find that DLS can misrepresent the size distribution of the colloidal dispersion and use SANS/SESANS to confirm that these perovskite solutions are mostly comprised of 1–2 nm-sized particles. We further conclude that if there are larger colloids present, their concentration must be <0.005% of the total dispersion volume. With SANS, we apply a simple fitting model for two component microemulsions (Teubner–Strey), demonstrating this as a potential method to investigate the structure, chemical composition, and colloidal stability of perovskite solutions, and we here show that MAPbI 3 solutions age more drastically than triple cation solutions.