Importance of Side-Chains on Molecular Characteristics of Interacting Organic Molecules

In this work, we have calculated several physical quantities related to two interacting semiconductor organic molecules to reveal the significance and the role of the side-chains. The molecular systems of our target are the geometry-optimized dimer systems: that consisting of two [6,6]-phenyl-C₆₁-butyric acid methyl ester molecules and that consisting of two peryline diimide-related molecules. The physical quantities shown in the present work are their relative molecular geometries, optimized energies, barycentric distances, angles between the two molecular planes, dipole moments, and electronic couplings. We have found that these physical quantities show quite different tendencies among the systems, which results from the absence/presence of the side-chains in these molecular species. It is emphasized that the presence of side-chains brings about the diversity of molecular characteristics in interacting molecules. This may point out the importance of side-chains in the various organic materials in general.

Nonfullerene Acceptor Molecules for Bulk Heterojunction Organic Solar Cells

The bulk-heterojunction blend of an electron donor and an electron acceptor material is the key component in a solution-processed organic photovoltaic device. In the past decades, a p-type conjugated polymer and an n-type fullerene derivative have been the most commonly used electron donor and electron acceptor, respectively. While most advances of the device performance come from the design of new polymer donors, fullerene derivatives have almost been exclusively used as electron acceptors in organic photovoltaics. Recently, nonfullerene acceptor materials, particularly small molecules and oligomers, have emerged as a promising alternative to replace fullerene derivatives. Compared to fullerenes, these new acceptors are generally synthesized from diversified, low-cost routes based on building block materials with extraordinary chemical, thermal, and photostability. The facile functionalization of these molecules affords excellent tunability to their optoelectronic and electrochemical properties. Within the past five years, there have been over 100 nonfullerene acceptor molecules synthesized, and the power conversion efficiency of nonfullerene organic solar cells has increased dramatically, from ∼2% in 2012 to >13% in 2017. This review summarizes this progress, aiming to describe the molecular design strategy, to provide insight into the structure-property relationship, and to highlight the challenges the field is facing, with emphasis placed on most recent nonfullerene acceptors that demonstrated top-of-the-line photovoltaic performances. We also provide perspectives from a device point of view, wherein topics including ternary blend device, multijunction device, device stability, active layer morphology, and device physics are discussed.

Selective sensing of citrate by a supramolecular ensemble formed by a phenazine copper(i) complex and a perylene diimide derivative

A PET based “off–on” fluorescent sensor for citrate has been developed, displaying low interference by other α-hydroxycarboxylates, dicarboxylates and monosaccharides.