Carbon nanotubes (CNTs) interlocked by cyclic compounds through supramolecular interaction are promising rotaxane-like materials applicable as 2D and 3D networks of nanowires and disease-specific theranostic agents having multifunctionalities. Supramolecular complexation of CNTs with cyclic compounds in a "ring toss'' manner is a straightforward method to prepare interlocked CNTs; however, to date, this has not been reported on. Here, the "ring toss" method to prepare interlocked CNTs by using π-conjugated carbon nanorings: [8]-, [9]-, and [10]cycloparaphenyleneacetylene (CPPA) is reported. CPPAs efficiently interact with CNTs to form CNT@CPPA complexes, while uncomplexed CPPAs can be recovered without decomposition. CNTs, which tightly fit in the cavities of CPPAs through convex-concave interaction, efficiently afford "tube-in-ring"-type CNT@CPPA complexes. "Tube-in-ring"-type and "ring-on-tube"-type complexation modes are successfully distinguished by spectroscopic, thermogravimetric, and microscopic analyses.

The close solid-state structure–property relationships of organic π−aromatic molecules have attracted interest due to their implications for the design of organic functional materials. In particular, a dimeric structure, that is, a unit consisting of two molecules, is required for precisely evaluating intermolecular interactions. Here, we show that the sidewall of a single-walled carbon nanotube (SWNT) represents a unique molecular dimer platform that can be directly visualized using high-resolution transmission electron microscopy. Pyrene is chosen as the π−aromatic molecule; its dimer is covalently linked to the SWNT sidewalls by aryl addition. Reflecting the orientation and separation of the two molecules, the pyrene dimer on the SWNT exhibits characteristic optical and photophysical properties. The methodology discussed here—form and probe molecular dimers—is highly promising for the creation of unique models and provides indispensable and fundamental information regarding molecular interactions.

Composite films that consisted of C and well-exfoliated nanosheets of transition metal dichalcogenides (TMDs), such as MoS or WS , with a bulk heterojunction structure were easily fabricated onto a semiconducting SnO electrode via a two-step methodology: self-assembly into their composite aggregates by injection of a poor solvent into a good solvent with the dispersion, and subsequent electrophoretic deposition. Upon photoexcitation, the composites on SnO exhibited enhanced transient conductivity in comparison with single components of TMDs or C , which demonstrates that the bulk heterojunction nanostructure of TMD and C promoted the charge separation (CS). In addition, the decoration of the TMD nanosheets with C hindered the undesirable charge recombination (CR) between an electron in SnO and a hole in the TMD nanosheets. Owing to the accelerated CS and suppressed CR, photoelectrochemical devices based on the MoS -C and WS -C composites achieved remarkably improved incident photon-to-current efficiencies (IPCEs) as compared with the single-component films. Despite more suppressed CR in WS -C than MoS -C , the IPCE value of the device with WS -C was smaller than that with MoS -C owing to its inhomogeneous film structure.

A series of chemically converted graphenes (CCGs) covalently functionalized with multiple zincporphyrins (ZnPs) through tuned lengths of linear oligo-p-phenylene bridges (ZnP-ph n -CCG, n = 1−5) were prepared to address the bridge length effect on their photodynamics. Irrespective of the bridge length, photoexcitation of ZnP-ph n -CCG led to exclusive formation of an exciplex state, which rapidly decayed to the ground state without yielding the completely charge-separated state. The notable dependence of the exciplex lifetime as a function of separation distance between the porphyrin and CCG has been observed for the first time, supporting the hypothesis that the decay to the ground state is dominated by the through-space interaction rather than the through-bond one. The basic information on the interaction between ZnP and CCG in the excited state will provide us with deeper insight on the intrinsic nature of the exciplex state as a function of donor− acceptor interaction.

The effects of the inclusion of reduced graphene oxide (RGO) in TiO 2 layers on performance of perovskite solar cells were systematically investigated. For this purpose, a wet chemical approach was examined to embed graphene oxide (GO) across the thickness of compact TiO 2 (cTiO 2 ) and mesoporous TiO 2 (mTiO 2 ) layers, which was followed by a thermally driven in situ conversion from GO to RGO. The presence of RGO at loadings of 0.15 wt % in the cTiO 2 layer and of 0.015 wt % in the mTiO 2 layer led to a power conversion efficiency (PCE) from 6.6% to 9.3% by 40% increase.In the last few years, solar cells based on organicinorganic hybrid halide perovskites (e.g., methylammonium lead halides CH 3 NH 3 PbX 3 , where X = halogen) have witnessed tremendous growth and continued to attract a huge interest.1 A typical cell architecture consists of a perovskite light-absorbing layer sandwiched between a hole-transporting material (HTM) 2,3 and electron-transporting compact TiO 2 (cTiO 2 ) layers. Mesoporous TiO 2 (mTiO 2 ) scaffolds are frequently integrated as the electron conduction pathway especially when a typical triiodide perovskite without other halides (CH 3 NH 3 PbI 3 ) is used, because the carrier diffusion length of CH 3 NH 3 PbI 3 is too short (ca. 100 nm) 4 to collect the carrier generated in the perovskite layer 5 effectively at the electrode. Nevertheless, the relatively slow electron diffusion through TiO 2 layers limits the charge conduction in the solar cells when combined with HTM with high hole conductivity such as doped 2,2¤,7,7¤-tetrakis(N,N-bis(p-methoxyphenyl)amino)-9,9¤-spirobifluorene (spiro-OMeTAD).6 For the improvement of device performances, maximizing the charge-transport properties in TiO 2 layers is one of the leading challenges.To address this challenge, employing carbon-based materials is a promising option. Graphene is an ordered network of hexagonally-linked carbon atoms arranged with periodicity that aids rapid transport of electrons.7 Reduced graphene oxide (RGO) possesses some defects but is functionally similar to graphene.8 It demonstrates graphene-like properties including transportation of charges are amenable to functionalization, and more importantly, RGO is less expensive and easier to process than graphene.9 RGO has proven compatibility with metals, metal oxides, and organic materials. 10 The integration of RGO with photoactive materials by adapting simple synthetic strategies offers immense advantages to cost-effective processing and device development.A recent report investigating the role of graphene in perovskite solar cells based on cTiO 2 and mesoporous Al 2 O 3 layers suggests that graphene incorporation in cTiO 2 layer lowers interfacial resistance between the cTiO 2 layer and FTO (fluorinedoped tin oxide) promoting charge transport.11 In addition, there are a few reports on the enhanced efficiencies of dye-sensitized solar cells by using graphenenanostructured TiO 2 composites as photoanode materials.12 On the basis of these reports and the observation involving...