Super resolution fluorescence microscopy is a key tool in the elucidation of biological fine-structure, providing insights into the distribution and interactions of biomolecular complexes down to the nanometer scale. Expansion microscopy is a recently developed approach for achieving nanoscale resolution on a conventional microscope. Here, biological samples are embedded in an isotropically swollen hydrogel. This physical expansion of the sample allows imaging with resolutions down to the tens-of-nanometers. However, because of the requirement that fluorescent labels are covalently bound to the hydrogel, standard, small-molecule targeting of fluorophores has proven incompatible with expansion microscopy. Here, we show a chemical linking approach that enables direct, covalent grafting of a targeting molecule and fluorophore to the hydrogel in expansion microscopy. We show application of this series of molecules in the antibody-free targeting of the cell cytoskeleton and in an example of lipid membrane staining for founders of Chrometra, a spin-off company, that commercializes the TRITON linkers.

Semiconductor-based light detection finds widespread application in everyday devices. Since the fabrication of commercial photodetectors requires complex and capital-intensive equipment, a search for semiconductors with low-cost processing is essential. To this end, hybrid organic–inorganic metal halide perovskites (MHPs) have gained interest due to their facile processing, in combination with their outstanding properties, such as efficient light absorption and high carrier mobility. Recently, all-inorganic CsPbBr3 has emerged as a promising candidate for photodetection due to its favorable intermediate bandgap and superior photostability, thermal stability, and moisture stability. Different synthesis strategies have been adopted to obtain highly crystalline CsPbBr3 perovskites with a large variety in morphology and dimension, each allowing for a specific photodetector application, e.g., cameras for hand-held devices, large-area flat panel detectors, and flexible light sensors. This Review provides a comprehensive overview and evaluation of the state-of-the-art preparation and photodetector integration of CsPbBr3 single crystals, microcrystals, nanowires, thin films, and nanocrystals.

Large polarons are known to form in lead halide perovskites (LHPs). Photoinduced isolated polarons at low densities have been well-researched, but many-body interactions at elevated polaron densities, exceeding the Mott criterion (i.e., Mott polaron density), have remained elusive. Here, employing ultrafast terahertz spectroscopy, we identify a stable Mott polaron state in LHPs at which the polaron wavefunctions start to overlap. The Mott polaron density is determined to be ∼1018 cm–3, in good agreement with theoretical calculations based on the Feynman polaron model. The electronic phase transition across the Mott density is found to be universal in LHPs and independent of the constituent ions. Exceeding the Mott polaron density, excess photoinjected charge carriers annihilate quickly within tens to hundreds of picoseconds, before reaching the stable and long-lived Mott state. These results have considerable implications for LHP-based devices and for understanding exotic phenomena reported in LHPs.

The addition of potassium thiocyanate (KSCN) to the FAPbBr 3 structure and subsequent post-treatment of nanocrystals (NCs) lead to high quantum confinement, resulting in a photoluminescent quantum yield (PLQY) approaching unity and microsecond decay times. This synergistic approach demonstrated exceptional stability under humid conditions, retaining 70% of the PLQY for over a month, while the untreated NCs degrade within 24 h. Additionally, the devices incorporating the post-treated NCs displayed 1.5% external quantum efficiency (EQE), a 5-fold improvement over untreated devices. These results provide promising opportunities for the use of perovskites in moisturestable optoelectronics.

All‐inorganic lead‐free Cs2AgBiBr6 double perovskites have gained significant attention due to their potential as stable and nontoxic photoactive semiconductors. Currently, it remains challenging to synthesize homogeneous microcrystals (MCs) exhibiting excellent properties, which are necessary for large‐area device integration. This work proposes a two‐step synthesis approach involving the introduction of a foreign silver cation to transform the 0D layered Cs3Bi2Br9 to 3D Cs2AgBiBr6 perovskite structure. This work has studied the cation exchange (CE) transformation mechanism by isolating intermediates to be able to follow the evolution of the crystal lattice as well as the structural and optical properties over time. Moreover, complete CE results in phase‐pure, highly crystalline Cs2AgBiBr6 MCs exhibiting excellent photonic properties, superior to their counterparts synthesized by anti‐solvent precipitation. These findings highlight the potential of CE‐induced transformation as a means of synthesizing novel, stable perovskites.