such as charge-carrier lifetimes and diffusion lengths in perovskite films should be maximized, which are sensitive to the density of sub-bandgap trap states acting as nonradiative recombination centers. [12,13] Long carrier lifetimes and diffusion lengths imply a reduction in trap densities constituted by multidimensional defects that can be broadly observed at the grain boundaries and surfaces of polycrystalline perovskite films. Therefore, defect modulation to efficiently suppress the undesired nonradiative recombination pathways in perovskite films have resulted in dramatically enhanced carrier lifetimes and diffusion lengths, which can be translated into higher open-circuit voltage (V OC) of photovoltaic devices. [14-18] Recently, surface post-treatments, such as depositing a layer of ammonium salts onto the perovskites, are the most frequently employed strategies, passivating the defects in the topmost area of the perovskite films. [19-22] However, the additional depositing procedure is considered to bring much uncertainty to the original perovskite films. [23,24] Recently, Yoo et al. demonstrated that the commonly used solvents (e.g., isopropanol) for dissolving ammonium salts, due to their strong polarity, had negative effects on the underlying perovskite films. [25] Lead halide perovskite films have witnessed rapid progress in optoelectronic devices, whereas polycrystalline heterogeneities and serious native defects in films are still responsible for undesired recombination pathways, causing insufficient utilization of photon-generated charge carriers. Here, radiationenhanced polycrystalline perovskite films with ultralong carrier lifetimes exceeding 6 μs and single-crystal-like electron-hole diffusion lengths of more than 5 μm are achieved. Prolongation of charge-carrier activities is attributed to the electronic structure regulation and the defect elimination at crystal boundaries in the perovskite with the introduction of phenylmethylammonium iodide. The introduced electron-rich anchor molecules around the host crystals prefer to fill the halide/organic vacancies at the boundaries, rather than form low-dimensional phases or be inserted into the original lattice. The weakening of the electron-phonon coupling and the excitonic features of the photogenerated carriers in the optimized films, which together contribute to the enhancement of carrier separation and transportation, are further confirmed. Finally the resultant perovskite films in fully operating solar cells with champion efficiency of 23.32% are validated and a minimum voltage deficit of 0.39 V is realized. Polycrystalline halide perovskites are of enormous excitement to be applied in highly efficient solar cells, [1-3] light-emitting diodes, [4] lasers, [5,6] and high-sensitivity photodetectors [7,8] due to their low fabricating costs [9,10] and excellent optoelectronic properties. [11] In order for these optoelectronic devices to access their theoretical performance limits, key metrics

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Capturing mitochondria’s intricate and dynamic structure poses a daunting challenge for optical nanoscopy. Different labeling strategies have been demonstrated for live-cell stimulated emission depletion (STED) microscopy of mitochondria, but orthogonal strategies are yet to be established, and image acquisition has suffered either from photodamage to the organelles or from rapid photobleaching. Therefore, live-cell nanoscopy of mitochondria has been largely restricted to two-dimensional (2D) single-color recordings of cancer cells. Here, by conjugation of cyclooctatetraene (COT) to a benzo-fused cyanine dye, we report a mitochondrial inner membrane (IM) fluorescent marker, PK Mito Orange (PKMO), featuring efficient STED at 775 nm, strong photostability, and markedly reduced phototoxicity. PKMO enables super-resolution (SR) recordings of IM dynamics for extended periods in immortalized mammalian cell lines, primary cells, and organoids. Photostability and reduced phototoxicity of PKMO open the door to live-cell three-dimensional (3D) STED nanoscopy of mitochondria for 3D analysis of the convoluted IM. PKMO is optically orthogonal with green and far-red markers, allowing multiplexed recordings of mitochondria using commercial STED microscopes. Using multi-color STED microscopy, we demonstrate that imaging with PKMO can capture interactions of mitochondria with different cellular components such as the endoplasmic reticulum (ER) or the cytoskeleton, Bcl-2-associated X protein (BAX)-induced apoptotic process, or crista phenotypes in genetically modified cells, all at sub-100 nm resolution. Thereby, this work offers a versatile tool for studying mitochondrial IM architecture and dynamics in a multiplexed manner.

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Inverted‐structure metal halide perovskite solar cells (PSCs) have attractive advantages like low‐temperature processability and outstanding device stability. The two‐step sequential deposition method shows the benefits of easy fabrication and decent performance repeatability. Nevertheless, it is still challenging to achieve high‐performance inverted PSCs with similar or equal power conversion efficiencies (PCEs) compared to the regular‐structure counterparts via this deposition method. Here, an improved two‐step sequential deposition technique is demonstrated via treating the bottom organic hole‐selective layer with the binary modulation system composed of a polyelectrolyte and an ammonium salt. Such improved sequential deposition method leads to the spontaneous refinement of up and buried interfaces for the perovskite films, contributing to high film quality with significantly reduced defect density and better charge transportation. As a result, the optimized PSCs show a large enhancement in the open‐circuit voltage by 100 mV and a dramatic lift in the PCE from 18.1% to 23.4%, delivering the current state‐of‐the‐art performances for inverted PSCs. Moreover, good operational and thermal stability is achieved upon the improved inverted PSCs. This innovative strategy helps gain a deeper insight into the perovskite crystal growth and defect modulation in the inverted PSCs based on the two‐step sequential deposition method.