Fluorescence fluctuation-based super-resolution microscopy using multimodal waveguided illumination.

Photonic chip-based total internal reflection fluorescence microscopy (c-TIRFM) is an emerging technology enabling a large TIRF excitation area decoupled from the detection objective. Additionally, due to the inherent multimodal nature of wide waveguides, it is a convenient platform for introducing temporal fluctuations in the illumination pattern. The fluorescence fluctuation-based nanoscopy technique multiple signal classification algorithm (MUSICAL) does not assume stochastic independence of the emitter emission and can therefore exploit fluctuations arising from other sources, as such multimodal illumination patterns. In this work, we demonstrate and verify the utilization of fluctuations in the illumination for super-resolution imaging using MUSICAL on actin in salmon keratocytes. The resolution improvement was measured to be 2.2-3.6-fold compared to the corresponding conventional images.

Chip-based multimodal super-resolution microscopy for histological investigations of cryopreserved tissue sections.

Histology involves the observation of structural features in tissues using a microscope. While diffraction-limited optical microscopes are commonly used in histological investigations, their resolving capabilities are insufficient to visualize details at subcellular level. Although a novel set of super-resolution optical microscopy techniques can fulfill the resolution demands in such cases, the system complexity, high operating cost, lack of multi-modality, and low-throughput imaging of these methods limit their wide adoption for histological analysis. In this study, we introduce the photonic chip as a feasible high-throughput microscopy platform for super-resolution imaging of histological samples. Using cryopreserved ultrathin tissue sections of human placenta, mouse kidney, pig heart, and zebrafish eye retina prepared by the Tokuyasu method, we demonstrate diverse imaging capabilities of the photonic chip including total internal reflection fluorescence microscopy, intensity fluctuation-based optical nanoscopy, single-molecule localization microscopy, and correlative light-electron microscopy. Our results validate the photonic chip as a feasible imaging platform for tissue sections and pave the way for the adoption of super-resolution high-throughput multimodal analysis of cryopreserved tissue samples both in research and clinical settings.

Spinel Co3O4 nanomaterials for efficient and stable large area carbon-based printed perovskite solar cells.

Carbon based perovskite solar cells (PSCs) are fabricated through easily scalable screen printing techniques, using abundant and cheap carbon to replace the hole transport material (HTM) and the gold electrode further reduces costs, and carbon acts as a moisture repellent that helps in maintaining the stability of the underlying perovskite active layer. An inorganic interlayer of spinel cobaltite oxides (Co3O4) can greatly enhance the carbon based PSC performance by suppressing charge recombination and extracting holes efficiently. The main focus of this research work is to investigate the effectiveness of Co3O4 spinel oxide as the hole transporting interlayer for carbon based perovskite solar cells (PSCs). In these types of PSCs, the power conversion efficiency (PCE) is restricted by the charge carrier transport and recombination processes at the carbon-perovskite interface. The spinel Co3O4 nanoparticles are synthesized using the chemical precipitation method, and characterized by X-ray diffraction (XRD), X-ray absorption spectroscopy (XAS), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and UV-Vis spectroscopy. A screen printed thin layer of p-type inorganic spinel Co3O4 in carbon PSCs provides a better-energy level matching, superior efficiency, and stability. Compared to standard carbon PSCs (PCE of 11.25%) an improved PCE of 13.27% with long-term stability, up to 2500 hours under ambient conditions, is achieved. Finally, the fabrication of a monolithic perovskite module is demonstrated, having an active area of 70 cm2 and showing a power conversion efficiency of >11% with virtually no hysteresis. This indicates that Co3O4 is a promising interlayer for efficient and stable large area carbon PSCs.

Effect of Formamidinium/Cesium Substitution and PbI2 on the Long-Term Stability of Triple-Cation Perovskites.

Altering cation and anion ratios in perovskites has proven an excellent means of tuning the perovskite properties and enhancing the performance. Recently, methylammonium/formamidinium/cesium triple-cation mixed-halide perovskites have demonstrated efficiencies up to 22 %. Similar to the widely explored methylammonium lead halide, excess PbI2 is added to these perovskite films to enhance their performances. The excess PbI2 is known to be beneficial for the performance. However, its impact on stability is less well known. Triple-cation perovskites deploy excess PbI2 up to 8 %. Thus, it is imperative to analyze the role of excess PbI2 in the degradation kinetics. In this study, the amount of PbI2 in the triple-cation perovskite films is varied and the degradation kinetics monitored by X-ray diffraction and optical absorption spectroscopy. The inclusion of excess PbI2 is shown to adversely affect the stability of the material. Faster degradation kinetics are observed for samples with higher PbI2 contents. However, samples with excess PbI2 also showed superior properties such as enhanced grain sizes and better optical absorption. Thus, careful management of the PbI2 quantity is required to obtain better stability and alternative pathways should be explored to achieve better device performance rather than adding excess PbI2 .