Selective Self-Assembly and Modification of Herringbone Reconstructions at a Solid-Liquid Interface of Au(111).

The precise control of molecular self-assembly on surfaces presents many opportunities for the creation of complex nanostructures. Within this endeavor, selective patterning by exploiting molecular interactions at the solid-liquid interface would be a beneficial capability. Using scanning tunneling microscopy at the 1,2,4-trichlorobenzene/Au(111) interface, we observed selective self-assembly of 1,3,5-tris(4-methoxyphenyl)benzene (TMPB) molecules in the face-centered cubic (FCC) regions of Au(111).

Switching Pathways of Triplet State Formation by Twisted Intramolecular Charge Transfer.

With the aim of constructing efficient photoelectric organic materials, a pyrido[3,2-]quinoline derivative named LA17b has been synthesized, and its photodynamic relaxation processes in solvents and films were studied by time-resolved fluorescence and femtosecond transient absorption techniques. The steady-state fluorescence spectra show pronounced red-shift with the increase of the solvent polarity as well as in binary solvent hexane/ethanol by increasing ethanol concentration. However, the strong red-shift does not lead to quenching of the fluorescence.

The classification of 1D `perovskites'.

There has been a huge amount of interest in perovskites recently and new structures of hybrid perovskites are frequently reported. The classification of perovskites has been unambiguous in the discussion of 3D and layered 2D perovskites due to the dimensional constraints. However, in 1D perovskites, the additional degrees of freedom have resulted in a large number of possible structural configurations.

Novel amphiphilic corannulene additive for moisture-resistant perovskite solar cells.

The addition of amphiphilic triethylene glycol based corannulene molecules provides multiple Lewis basic sites that assist in perovskite grain growth, and improve the charge carrier collection and moisture resistance of perovskite solar cells. This study paves the way for utilization of more molecules from corannulene families in perovskite research.

Electrochemical Properties of Anthracene-Based Lithium-Solvated Electron Solutions.

The conductivity and open-circuit voltage (OCV) of lithium-solvated electron solutions (LiSESs) based on anthracene in tetrahydrofuran were studied by both experimental measurements and density functional theory calculations with a range-separated functional based on the M06 form and the Solvation Model based on Density (SMD). The OCV was found to decrease with increasing temperature and the ratio of lithium to anthracene. The enthalpy change (Δ) of LiSESs was the internal energy change of the cell reaction.

Synthesis and Electronic Properties of Novel 5,7-Diazapentacene Derivatives.

A route to the synthesis of novel 5,7-diazapentacenes and some preliminary studies on their properties is reported. A single crystal X-ray diffraction study of the dihexyl derivative showed it had formed a dimer during the analysis. The materials possess lower lying frontier orbitals than pentacene and may have potential applications in organic electronic devices.

3D FTO/FTO-Nanocrystal/TiO Composite Inverse Opal Photoanode for Efficient Photoelectrochemical Water Splitting.

A 3D fluorine-doped SnO (FTO)/FTO-nanocrystal (NC)/TiO inverse opal (IO) structure is designed and fabricated as a new "host and guest" type of composite photoanode for efficient photoelectrochemical (PEC) water splitting. In this novel photoanode design, the highly conductive and porous FTO/FTO-NC IO acts as the "host" skeleton, which provides direct pathways for faster electron transport, while the conformally coated TiO layer acts as the "guest" absorber layer. The unique composite IO structure is fabricated through self-assembly of colloidal spheres template, a hydrothermal method and atomic layer deposition (ALD).

A room-temperature refuelable lithium, iodine and air battery.

We demonstrate a new refuelable lithium cell using lithium solvated electron solution (Li-SES) as anolyte and iodine solutions as catholyte. This cell shows a high OCV (~3 V). Unlike conventional rechargeable Li batteries, this kind of cell can be re-fueled in several minutes by replacing the spent liquids.

1,3,5-Triphenylbenzene and Corannulene as Electron Receptors for Lithium Solvated Electron Solutions.

The authors report on conductivity studies carried out on lithium solvated electron solutions (LiSES) prepared using two types of polyaromatic hydrocarbons (PAH), namely 1,3,5-triphenylbenzene and corannulene, as electron receptors. The solid PAHs were first dissolved in tetrahydrofuran (THF) to form a solution. Metallic lithium was then dissolved into these PAH/THF solutions to yield either blue or greenish blue solutions, colors which are indicative of the presence of solvated electrons.

Facile Synthesis of a Furan-Arylamine Hole-Transporting Material for High-Efficiency, Mesoscopic Perovskite Solar Cells.

A novel hole-transporting molecule (F101) based on a furan core has been synthesized by means of a short, high-yielding route. When used as the hole-transporting material (HTM) in mesoporous methylammonium lead halide perovskite solar cells (PSCs) it produced better device performance than the current state-of-the-art HTM 2,2',7,7'-tetrakis-(N,N-di-p-methoxyphenylamine)-9,9'-spirobifluorene (spiro-OMeTAD). The F101-HTM-based device exhibited both slightly higher Jsc (19.

Interfacial Charge Transfer Anisotropy in Polycrystalline Lead Iodide Perovskite Films.

Solar cells based on organic-inorganic lead iodide perovskite (CH3NH3PbI3) exhibit remarkably high power conversion efficiency (PCE). One of the key issues in solution-processed films is that often the polycrystalline domain orientation is not well-defined, which makes it difficult to predict energy alignment and charge transfer efficiency. Here we combine ab initio calculations and photoelectron spectroscopy to unravel the electronic structure and charge redistribution at the interface between different surfaces of CH3NH3PbI3 and typical organic hole acceptor Spiro-OMeTAD and electron acceptor PCBM.

1,5,9-Triaza-2,6,10-triphenylboracoronene: BN-embedded analogue of coronene.

A novel BN-fused coronene derivative 1,5,9-triaza-2,6,10-triphenylboracoronene (1) has been successfully synthesized in one step from 2,3,6,7,9,10-hexamethoxy-1,5,9-triamino-triphenylene. Compound 1 has been investigated using photophysical, electrochemical, and molecular simulation methods. Interestingly, three phenyl groups at B centers in compound 1 can be replaced by hydroxyl units stepwise through hydroxylation in wet organic solvents, leading to changes in the packing and physical properties.

Naphthalene-, anthracene-, and pyrene-substituted fullerene derivatives as electron acceptors in polymer-based solar cells.

A series of aryl-substituted fullerene derivatives were prepared in which the aromatic moiety of [6,6]-phenyl C61-butyric acid methyl ester (PC61BM) was modified by replacing the monocyclic phenyl ring with bicyclic naphthalene (NC61BM), tricyclic anthracene (AC61BM), and tetracyclic pyrene (PyC61BM). The PC61BM derivatives were synthesized from C60 using tosylhydrazone and were tested as electron acceptors in poly(3-hexylthiophene) (P3HT)-based organic photovoltaic cells (OPVs). The lowest unoccupied molecular orbital (LUMO) energy level of NC61BM (-3.

Comparative studies on rigid π linker-based organic dyes: structure-property relationships and photovoltaic performance.

A series of six structurally correlated donor-π bridge-acceptor organic dyes were designed, synthesized, and applied as sensitizers in dye-sensitized solar cells. Using the most widely studied donor (triarylamine) and cyclopenta[1,2-b:5,4-b']dithiophene or cyclopenta[1,2-b:5,4-b']dithiophene[2',1':4,5]thieno[2,3-d]thiophene as π spacers, their structure-property relationships were investigated in depth by photophysical techniques and theoretical calculations. It was found that the photovoltaic performance of these dyes largely depends on their electronic structures, which requires synergistic interaction between donors and acceptors.

Self-Assembly of Conjugated Units Using Metal-Terpyridine Coordination.

Due to their inherently dynamic natures and fascinating photoluminescent/photoelectronic properties, coordination compounds of metal ions and conjugated terpyridine ligands have attracted considerable attention as functional materials for a variety of potential applications. In this feature article, a summary of recent work toward the development of one- (1D), two- (2D), and three-dimensional (3D) supramolecular polymers, networks, and metallomacrocycles based on zinc metal ion coordination of conjugated units bearing terpyridine ligands is presented, and it is shown how it fits within the overall framework of work in this field. Here, a sequential study from terpyridines as basic building blocks to their zinc-coordinated supramolecular 1D polymers, 2D macrocycles, and 2D and 3D networks is developed.

Hole-transporting small molecules based on thiophene cores for high efficiency perovskite solar cells.

Two new electron-rich molecules, 2,3,4,5-tetra[4,4'-bis(methoxyphenyl)aminophen-4"-yl]-thiophene (H111) and 4,4',5,5'-tetra[4,4'-bis(methoxyphenyl)aminophen-4"-yl]-2,2'-bithiophene (H112), which contain thiophene cores with arylamine side groups, are reported. When used as the hole-transporting material (HTM) in perovskite-based solar cell devices, power conversion efficiencies of up to 15.4% under AM 1.

Cobalt dopant with deep redox potential for organometal halide hybrid solar cells.

In this work, we report a new cobalt(III) complex, tris[2-(1H-pyrazol-1-yl)pyrimidine]cobalt(III) tris[bis(trifluoromethylsulfonyl)imide] (MY11), with deep redox potential (1.27 V vs NHE) as dopant for 2,2',7,7'-tetrakis-(N,N-di-p-methoxyphenylamine)-9,9'-spirobifluorene (spiro-OMeTAD). This dopant possesses, to the best of our knowledge, the deepest redox potential among all cobalt-based dopants used in solar cell applications, allowing it to dope a wide range of hole-conductors.

A simple 3,4-ethylenedioxythiophene based hole-transporting material for perovskite solar cells.

We report a novel electron-rich molecule based on 3,4-ethylenedioxythiophene (H101). When used as the hole-transporting layer in a perovskite-based solar cell, the power-conversion efficiency reached 13.8 % under AM 1.

Enhancing the performance of solution-processed bulk-heterojunction solar cells using hydrogen-bonding-induced self-organization of small molecules.

Small-molecule solar-cell performance is highly sensitive to the crystallinity and intermolecular connectivity of the molecules. In order to enhance the crystallinity for the solution-processed small molecule, it is possible to make use of carboxylic acid end-functional groups to drive hydrogen-bonding-induced π-π stacking of conjugated molecules. Herein, we report the synthesis and characterization of quarterthiophenes with carboxylic acid as end groups.

High open circuit voltage organic photovoltaic cells fabricated using 9,9'-bifluorenylidene as a non-fullerene type electron acceptor.

We have found that 9,9'BF can be used as an electron acceptor for P3HT-based OPVs while similar devices using 4,4'BP do not show any photovoltaic effect. This can be related to the respective aromaticity and antiaromaticity of the reduced forms of 9,9'BF or 4,4'BP. The OPV device fabricated using P3HT and 9,9'BF exhibited a PCE of 2.

Photovoltage enhancement from cyanobiphenyl liquid crystals and 4-tert-butylpyridine in Co(II/III) mediated dye-sensitized solar cells.

Two cyanobiphenyl liquid crystals (LCs), 5CB (4-cyano-4'-pentylbiphenyl) and 8CB (4-cyano-4'-octylbiphenyl), are introduced as additives into Co(II/III) electrolytes for dye-sensitized solar cells (DSCs). An electrolyte containing a combination of these LCs and 4-tert-butylpyridine (TBP) exhibits higher photovoltage than one with only TBP, resulting in higher power conversion efficiency.

New donor-π-acceptor sensitizers containing 5H-[1,2,5]thiadiazolo [3,4-f]isoindole-5,7(6H)-dione and 6H-pyrrolo[3,4-g]quinoxaline-6,8(7H)-dione units.

Two new D-π-A sensitizers (L101 and L102) incorporating 5H-[1,2,5]thiadiazolo [3,4-f]isoindole-5,7(6H)-dione and 6H-pyrrolo[3,4-g]quinoxaline-6,8(7H)-dione core structures were synthesized and tested in liquid dye-sensitized solar cells (DSCs). L102 achieved a promising power conversion efficiency (PCE) of 6.2% (AM 1.

Large two-photon absorption of terpyridine-based quadrupolar derivatives: towards their applications in optical limiting and biological imaging.

Developing organic chromophores with large two-photon absorption (TPA) in both organic solvents and aqueous media is crucial owing to their applications in solid-state photonic devices and biological imaging. Herein, a series of novel terpyridine-based quadrupolar derivatives have been synthesized. The influences of electron-donating group, type of conjugated bridge, as well as solvent polarity on the molecular TPA properties have been investigated in detail.

Synthesis and characterization of a series of annelated benzotriazole based polymers with variable bandgap.

Here we report the synthesis and characterization of a series of annelated benzotriazole based polymers with variable bandgap. Benzobistriazole monomers reported by us previously were desymmetrized using partial reduction ring opening followed by ring closure to produce a wide range of annelated benzotriazole based monomers. These monomers were co-polymerized with a fluorene moiety to give polymers with bandgaps ranging from 1.