Photoinduced photoluminescence enhancement in self-assembled clusters of formamidinium lead bromide perovskite nanocrystals.

Nanocrystals of formamidinium lead bromide perovskite (FAPbBr3) self-assemble into clusters in powder and film samples and provide a prolonged photoluminescence lifetime, which is attributed to the diffusion of charge carriers through interparticle states formed among nanocrystals. Interestingly, the photoluminescence lifetime decreases and the emission intensity increases for the clusters, which is with the increase in the intensity of excitation light. By doping the nanocrystal clusters with C60, we successfully harvested the photogenerated charge carriers.

Preferential Face-on and Edge-on Orientation of Thiophene Oligomers by Rational Molecular Design.

Precise control over the supramolecular organization of organic semiconducting materials guiding to exclusive face-on or edge-on orientation is a challenging task. In the present work, we study the preferential packing of thiophene oligomers induced through rational molecular designing and self-assembly. The acceptor-donor-acceptor-type oligomers having 2-(1,1-dicyano-methylene)rhodanine as acceptor (OT1) favored a face-on packing, whereas that of functionalized with N-octyl rhodanine (OT2) preferred an edge-on packing as evident from 2D-grazing incidence angle X-ray diffraction, tapping-mode atomic force microscopy (AFM) and Raman spectroscopy analyses.

Effect of Differential Self-Assembly on Mechanochromic Luminescence of Fluorene-Benzothiadiazole-Based Fluorophores.

Supramolecular self-assembly is an excellent tool for controlling the optical and electronic properties of chromophore-based molecular systems. Herein, we demonstrate how differential self-assembly affects mechanoresponsive luminescence of fluorene-benzothiadiazole-based fluorophores. We have synthesized two donor-acceptor-donor-type conjugated oligomers consisting of fluorene as the donor and benzothiadiazole as the acceptor.

Zero-Dimensional Methylammonium Bismuth Iodide-Based Lead-Free Perovskite Capacitor.

Symmetrical electrochemical capacitors are attracting immense attention because of their fast charging-discharging ability, high energy density, and low cost of production. The current research in this area is mainly focused on exploring novel low-cost electrode materials with higher energy and power densities. In the present work, we fabricated an electrochemical double-layer capacitor using methylammonium bismuth iodide (CHNH)BiI, a lead-free, zero-dimensional hybrid perovskite material.

Self-Assembled Organic Materials for Photovoltaic Application.

Organic photovoltaic cells based on bulk-heterojunction architecture have been a topic of intense research for the past two decades. Recent reports on power conversion efficiency surpassing 10% suggest these devices are a viable low-cost choice for a range of applications where conventional silicon solar cells are not suitable. Further improvements in efficiency could be achieved with the enhanced interaction between the donor and acceptor components.

CH NH PbBr Perovskite Nanocrystals as Efficient Light-Harvesting Antenna for Fluorescence Resonance Energy Transfer.

Hybrid perovskites have created enormous research interest as a low-cost material for high-performance photovoltaic devices, light-emitting diodes, photodetectors, memory devices and sensors. Perovskite materials in nanocrystal form that display intense luminescence due to the quantum confinement effect were found to be particularly suitable for most of these applications. However, the potential use of perovskite nanocrystals as a light-harvesting antenna for possible applications in artificial photosynthesis systems is not yet explored.

Channeling Exciton Migration into Electron Transfer in Formamidinium Lead Bromide Perovskite Nanocrystal/Fullerene Composites.

Hydrophobically capped nanocrystals of formamidinium lead bromide (FAPbBr ) perovskite (PNC) show bright and stable fluorescence in solution and thin-film states. When compared with isolated PNCs in a solution, close-packed PNCs in a thin film show extended fluorescence lifetime (ca. 4.

Formation of Coaxial Nanocables with Amplified Supramolecular Chirality through an Interaction between Carbon Nanotubes and a Chiral π-Gelator.

In an attempt to gather experimental evidence for the influence of carbon allotropes on supramolecular chirality, we found that carbon nanotubes (CNTs) facilitate amplification of the molecular chirality of a π-gelator (MC-OPV) to supramolecular helicity at a concentration much lower than that required for intermolecular interaction. For example, at a concentration 1.8×10(-4)  m, MC-OPV did not exhibit a CD signal; however, the addition of 0-0.

p/n-Polarity of thiophene oligomers in photovoltaic cells: role of molecular vs. supramolecular properties.

Molecular and supramolecular properties play key roles in the optoelectronic properties and photovoltaic performances of organic materials. In the present work, we show how small changes in the molecular structure affect such properties, which in turn control the intrinsic and fundamental properties such as the p/n-polarity of organic semiconductors in bulk-heterojunction solar cells. Herein, we designed and synthesized two acceptor-donor-acceptor type semiconducting thiophene oligomers end-functionalized with oxazolone/isoxazolone derivatives (OT1 and OT2 respectively).

Organic donor-acceptor assemblies form coaxial p-n heterojunctions with high photoconductivity.

The formation of coaxial p-n heterojunctions by mesoscale alignment of self-sorted donor and acceptor molecules, important to achieve high photocurrent generation in organic semiconductor-based assemblies, remains a challenging topic. Herein, we show that mixing a p-type π gelator (TTV) with an n-type semiconductor (PBI) results in the formation of self-sorted fibers which are coaxially aligned to form interfacial p-n heterojunctions. UV/Vis absorption spectroscopy, powder X-ray diffraction studies, atomic force microscopy, and Kelvin-probe force microscopy revealed an initial self-sorting at the molecular level and a subsequent mesoscale self-assembly of the resulted supramolecular fibers leading to coaxially aligned p-n heterojunctions.

A carbazole-fluorene molecular hybrid for quantitative detection of TNT using a combined fluorescence and quartz crystal microbalance method.

A combined fluorescence and quartz-crystal microbalance approach for the quantitative sensing of nitroaromatics, particularly TNT, using morphologically different self-assemblies of a carbazole bridged fluorene (CBF) derivative is described. Picomolar level detection of TNT was possible in water by the CBF nanoparticles and nanogram level TNT sensing in the vapour phase could be achieved with the CBF supramolecular rods.