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Flexible perovskite solar cells (PSCs) have attracted considerable attention due to their excellent performance, low-cost, and great potential as an energy supplier for soft electronic devices. In particular, the design of charge transporting layers (CTLs) is crucial to the development of highly efficient and flexible PSCs. Herein, nanocrystalline Ti-based metal-organic framework (nTi-MOF) particles are synthesized to have ca. 6 nm in diameter. These are then well-dispersed in alcohol solvents in order to generate electron transporting layers (ETLs) in PSCs under ambient temperatures using a spin-coating process. The electronic structure of nTi-MOF ETL is found to be suitable for charge injection and transfer from the perovskite to the electrodes. The combination of a [6,6]-phenyl-C-butyric acid (PCBM) into the nTi-MOF ETL provides for efficient electron transfer and also suppresses direct contact between the perovskite and the electrode. This results in impressive power conversion efficiencies (PCEs) of 18.94% and 17.43% for rigid and flexible devices, respectively. Moreover, outstanding mechanical stability is retained after 700 bending cycles at a bending radius ( r) of 10 mm.

Porous metal-organic-frameworks (MOFs) are attractive materials for gas storage, separations, and catalytic reactions. A challenge exists, however, on how to introduce larger pores juxtaposed with the inherent micropores in different forms of MOFs, which would enable new functions and applications. Here we report the formation of heterogeneous pores within MOF particles, patterns, and membranes, using a discriminate etching chemistry, called silver-catalyzed decarboxylation. The heterogeneous pores are formed, even in highly stable MOFs, without altering the original structure. A decarboxylated MOF membrane is shown to have pH-responsive switchable selectivity for the flow-assisted separation of similarly sized proteins. We envision that our method will allow the use of heterogeneous pores for massive transfer and separation of complex and large molecules, and that the capability for patterning and positioning heterogeneous MOF films on diverse substrates bodes well for various energy and electronic device applications.

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Challenges exist in taking advantage of dye molecules for reliable and reproducible molecular probes in biomedical applications. In this study, we show how to utilize the dye molecules for bioimaging within protective carriers of nanocrystalline metal-organic frameworks (nMOFs) particles. Specifically, Resorufin and Rhodamine-6G having different molecular sizes were encapsulated within close-fitting pores of nMOF-801 and nUiO-67 particles, respectively. The resulting nanocrystalline particles have high crystallinity, uniform size, and morphology and preserve enhanced photoluminescence properties with exceptional stabilities in biomedical environment. The samples are further functionalized with a targeting agent and successfully work for fluorescence imaging of FL83B (human hepatocyte cell) and HepG2 (human hepatocellular carcinoma) without cytotoxicity.

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A metal-organic framework (MOF) is composed of secondary building units (SBUs) of metal ions and organic ligands to link each SBU. Moreover, the photosynthetic synthesis of a valuable CO chemical from carbon dioxide (CO2) represents an important class of appealing methods. Herein, we find that a molecular photocatalyst with high selectivity and activity can be designed via a fine balance in the proximity of Re complex (ReI(CO)3(BPYDC)(Cl), BPYDC = 2,2′-bipyridine-5,5′-dicarboxylate) and -NH2 functionalized multiple ligands composing a MOF photocatalyst, denoted as Re-MOF-NH2. These ligands in Re-MOF-NH2 has been confirmed by infrared, UV-visible, and 1H nuclear magnetic resonance spectra. Moreover, we show from extended X-ray absorption fine structure and in-situ infrared spectra that the bond corresponding to Re-CO upon introduction of -NH2 functional groups is divided into asymmetric bonds of 1.4 Å and 2.3 Å along with different CO2 vibrations, thus making the configuration of carbonyl groups in a Re metal complex become asymmetric in addition to aiding formation of CO2 intermediates within Re-MOF-NH2. Indeed, both of the uneven electron distribution in asymmetric carbonyl groups for Re-CO and the intermolecular stabilization of carbamate intermediates are proven to give the approximately 3-fold increase in photocatalytic activity for conversion of CO2 into CO.

Mammalian cells are promising agents for cell therapy, diagnostics, and drug delivery. For full utilization of the cells, development of an exoskeleton may be beneficial to protecting the cells against the environmental stresses and cytotoxins to which they are susceptible. We report here a rapid single-step method for growing metal–organic framework (MOF) exoskeletons on a mammalian cell surface under cytocompatible conditions. The MOF exoskeleton coating on the mammalian cells was developed via a one-pot biomimetic mineralization process. With the exoskeleton on, the individual cells were successfully protected against cell protease (i.e., Proteinase K), whereas smaller-sized nutrient transport across the exoskeleton was maintained. Moreover, vital cellular activities mediated by transmembrane GLUT transporter proteins were also unaffected by the MOF exoskeleton formation on the cell surfaces. Altogether, this ability to control the access of specific molecules to a single cell through the porous exoskeleton, along with the cytoprotection provided, should be valuable for biomedical applications of mammalian cells.