Organic-inorganic hybrid perovskite materials have been receiving considerable attention due to their promising applications in many optoelectronic fields. However, some of the fundamental properties of perovskite materials are still disputed, because most of them are derived from a thin-film state. To comprehend the intrinsic characteristics in a single crystal, herein we report, for the first time, the bulk crystal growth of CH 3 NH 3 PbI 3 . Single crystals of tetragonal CH 3 NH 3 PbI 3 with dimensions of 10 mm × 10 mm × 8 mm were grown by a temperature-lowering method in HI solution. Studies in to the refinement and orientations of the CH 3 NH 3 PbI 3 single crystal structure were conducted based on a high quality crystal.The absorption edge of a CH 3 NH 3 PbI 3 single crystal was located at about 836 nm, indicating that the band gap of CH 3 NH 3 PbI 3 is approximately 1.48 eV, which is close to the theoretical results and smaller than those derived from polycrystalline and thin-films. CH 3 NH 3 PbI 3 crystal exhibits a relatively wide absorption (from 250 nm to 800 nm) and a relatively good thermal stability. CrystEngCommThis journal is † Electronic supplementary information (ESI) available. CCDC 1029776; the images of white MAI, white with yellow MAI and residue light yellow PbI 2 ; powder X-ray diffraction patterns for MAI; 1 H-NMR and 13 C-NMR spectra of MAI; selected bond lengthIJÅ) and bond anglesIJdeg) for β-MAPbI 3 , isotropic and anisotropic displacement parameters of MAPbI 3 . See

Three types of TiO‐compound‐based nanobelts (Na2Ti3O7, H2Ti3O7, TiO2) are prepared from commercial TiO2 powders via an alkaline hydrothermal process. Nanostructured sheets based on the as‐synthesized nanobelts are prepared using a paper‐making process. The nanobelts are connected with hydrogen bonds or/and bridge oxygen atoms and packed together, forming a paperlike porous network structure, with an average pore size of ∼500 nm. The electrical properties and gas sensing of the nanostructured sheets are demonstrated to display sensitivity down to sub‐ppb levels. H2Ti3O7 nanobelts decorated with Ag nanoparticles have also been applied as an antibacterial agent.

The molecular-level motions of a coronene-based supramolecular rotator are amplified into macroscopic changes of crystals by co-assembly of coronene and TCNB (1,2,4,5-tetracyanobenzene) into a charge-transfer complex. The as-prepared cocrystals show remarkable self-healing behavior and thermo-mechanical responses during thermally-induced reversible single-crystal-to-single-crystal (SCSC) phase transitions. Comprehensive analysis of the microscopic observations as well as differential scanning calorimetry (DSC) measurements and crystal habits reveal that a thermally-reduced-rate-dependent dynamic character exists in the phase transition. The crystallographic studies show that the global similarity of the packing patterns of both phases with local differences, such as molecular stacking sequence and orientations, should be the origin of the self-healing behavior of these crystals.

Aggregation induced emission (AIE) is an amazing property for light emitting materials and has attracted much attention. Here, we report a new kind of AIE materials: fluorenone derivates 2,7-dip-tolyl-fluorenone (DTFO) and 2,7-bis(4-(tert-butylthio)phenyl)-fluorenone (DSFO). Strong light emissions with a large Stokes shift and long lifetime in the solid state originate from the formation of excimers. The crystal structure of DSFO shows that every two molecules are bound together even in the ground state by intermolecular hydrogen bonds and form a particular dimer. When this dimer is excited, it turns into an excimer without arrangement adjustment and likewise without repulsive interactions when the excimer decays back to the dimer; so, the nonradiative decay pathways that exist in common excimers are greatly reduced and thus induce a strongly enhanced luminescence in the solid state. OLED devices employing DTFO as light emitting layers are fabricated and evaluated.

Physical properties of active materials built up from small molecules are dictated by their molecular packing in the solid state. Here we demonstrate for the first time the growth of n-channel single-crystal field-effect transistors and organic thin-film transistors by sublimation of 2,6-dichloro-naphthalene diimide in air. Under these conditions, a new polymorph with two-dimensional brick-wall packing mode (b-phase) is obtained that is distinguished from the previously reported herringbone packing motif obtained from solution (a-phase). We are able to fabricate single-crystal field-effect transistors with electron mobilities in air of up to 8.6 cm 2 V À 1 s À 1 (a-phase) and up to 3.5 cm 2 V À 1 s À 1 (b-phase) on n-octadecyltriethoxysilane-modified substrates. On silicon dioxide, thin-film devices based on b-phase can be manufactured in air giving rise to electron mobilities of 0.37 cm 2 V À 1 s À 1 . The simple crystal and thin-film growth procedures by sublimation under ambient conditions avoid elaborate substrate modifications and costly vacuum equipment-based fabrication steps.

We report here a new polymorph of cocrystal CuQ2-TCNQ that shows an oriented single-crystal-to-single-crystal phase transition along its a-axis at ambient conditions. Upon mechanical stimulation, it converts into another polymorph accompanied by almost doubling its length and halving its thickness. Our crystallographic studies indicate the dramatic changes in crystal dimensions resulted from the prominent changes of molecular stacking patterns. A reasonable mechanism for the phenomenon was proposed on the basis of the structural, microscopic, and thermal analysis.

Organic cocrystals possess valuable properties owing to the synergistic effect of the individual components. However, the growth of molecular cocrystals is still in its primary stage. Here we develop a microspacing in-air sublimation method to grow organic cocrystals, and furthermore to realize morphology control on them, which is essential for structure–property relations. A series of polycyclic aromatic hydrocarbon (PAH)‒1,2,4,5-tetracyanobenzene (TCNB) complexes cocrystals are grown directly on the substrate, with the morphology tunable from 1D needle-like to 2D plate-like on demand. Spatially resolved photoluminescence spectra analyses on different cocrystals display morphology dependent and anisotropic optical waveguiding properties. In situ observation and energy calculations of the crystallization processes reveal the formation mechanism being from a competition between growth kinetics-defined crystal habit and the thermodynamics driving force. This growth technique may serve the future demand for tunable morphology organic cocrystals in different functional applications.

Organic single crystals manifest the intrinsic physical properties of materials. However, traditional growth of organic single crystals is limited by low solubility from solutions or complexity from physical vapor deposition. Here we report a new method to grow organic single crystals by microspacing in-air sublimation, which avoids costly vacuum system and time-consuming procedures and is practical for a wide range of organic crystals. In situ crystal growth observation revealed an unprecedented vapor-to-melt-to-crystal mechanism, resulting from the micrometer scale spacing distance between the source and the growth position. FET devices based on the rubrene crystals directly grown on Si/SiO2 substrate exhibited higher mobility than the best record using SiO2 as the gate dielectric. This effective organic crystal growth technique can be affordable and handled for almost every lab, which may be beneficial for future research and application of organic crystals.