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

A supramolecular approach has been developed for the preparation of supramolecular nanoparticles (SNPs) with variable sizes (30-450 nm) from three different molecular building blocks using a cyclodextrin/adamantane recognition system. Positron emission tomography (PET) was employed to study the biodistribution and lymph node drainage of the SNPs in mice. The sizes of the SNPs affect their in vivo characteristics (see picture).

Defects at the bulk grain boundaries and heterojunction interfaces could dictate the power losses of perovskite solar cells (PSCs) during the operation process, which are regarded as major roadblocks towards...

The benefits of excess PbI 2 on perovskite crystal nucleation and growth are countered by the photoinstability of interfacial PbI 2 in perovskite solar cells (PSCs). Here we report a simple chemical polishing strategy to rip PbI 2 crystals off the perovskite surface to decouple these two opposing effects. The chemical polishing results in a favorable perovskite surface exhibiting enhanced luminescence, prolonged carrier lifetimes, suppressed ion migration, and better energy level alignment. These desired benefits translate into increased photovoltages and fill factors, leading to high-performance mesostructured formamidinium lead iodide-based PSCs with a champion efficiency of 24.50%. As the interfacial ion migration paths and photodegradation triggers, dominated by PbI 2 crystals, were eliminated, the hysteresis of the PSCs was suppressed and the device stability under illumination or humidity stress was significantly improved. Moreover, this new surface polishing strategy can be universally applicable to other typical perovskite compositions.

Aus drei Bausteinen entstehen auf der Grundlage eines Cyclodextrin‐Adamantan‐Erkennungssystems supramolekulare Nanopartikel (SNPs) variabler Größe (30–450 nm). Die Bioverteilung und Lymphknotendrainage der SNPs in Mäusen wurde mit Positronenemissionstomographie untersucht. Die Größen der SNPs beeinflussen ihr In‐vivo‐Verhalten (siehe Bild).

A prerequisite for commercializing perovskite photovoltaics is to develop a swift and eco‐friendly synthesis route, which guarantees the mass production of halide perovskites in the industry. Herein, a green‐solvent‐assisted mechanochemical strategy is developed for fast synthesizing a stoichiometric δ‐phase formamidinium lead iodide (δ‐FAPbI3) powder, which serves as a high‐purity precursor for perovskite film deposition with low defects. The presynthesized δ‐FAPbI3 precursor possesses high concentration of micrometer‐sized colloids, which are in favor of preferable crystallization by spontaneous nucleation. The resultant perovskite films own preferred crystal orientations of cubic (100) plane, which is beneficial for superior carrier transport compared to that of the films with isotropic crystal orientations using “mixture of PbI2 and FAI” as precursors. As a result, high‐performance perovskite solar cells with a maximum power conversion efficiency of 24.2% are obtained. Moreover, the δ‐FAPbI3 powder shows superior storage stability for more than 10 months in ambient environment (40 ± 10% relative humidity), being conducive to a facile and practical storage for further commercialization.

A variety of defects exist on the crystalline surfaces of solution-processed polycrystalline perovskites, resulting in photovoltaic output losses and subsequent degradations. It is necessary to develop a versatile passivator that can concurrently eliminate multiple defects, including vacancy, interstitial, antisite substitution, and dissociative I2. Herein, we focus on multiple-defect management to optimize defective perovskite surfaces by using three kinds of chemical bonds with a pyridine-containing polymeric agent. Coordination bonds alleviate the distorted PbI x octahedrons by digesting I vacancies, and hydrogen bonds stabilize ammonium cations to eliminate organic vacancies and deep-level antisite defects. Furthermore, the dissociated I2 acting as electron traps from the coupled I interstitials could be blocked by supramolecular halogen bonds. Based on the low-defect perovskite films, substantial increases in photovoltaic efficiencies, going up to 22.02% and 23.14%, are achieved in planar and mesoporous devices, respectively, with nonencapsulated cells retaining 90% of their original efficiencies after 2200 h of aging in ambient conditions.

SummaryMicrofluidic reactors exhibit intrinsic advantages of reduced chemical consumption, safety, high surface-area-to-volume ratios, and improved control over mass and heat transfer superior to the macroscopic reaction setting. In contract to a continuous-flow microfluidic system composed of only a microchannel network, an integrated microfluidic system represents a scalable integration of a microchannel network with functional microfluidic modules, thus enabling the execution and automation of complicated chemical reactions in a single device. In this review, we summarize recent progresses on the development of integrated microfluidics-based chemical reactors for (i) parallel screening of in situ click chemistry libraries, (ii) multistep synthesis of radiolabeled imaging probes for positron emission tomography (PET), (iii) sequential preparation of individually addressable conducting polymer nanowire (CPNW), and (iv) solid-phase synthesis of DNA oligonucleotides. These proof-of-principle demonstrations validate the feasibility and set a solid foundation for exploring a broad application of the integrated microfluidic system.