Melissa Ball - Academia.edu (original) (raw)

Papers by Melissa Ball

Chemistry of Materials, 2022

Journal of Materials Chemistry C

To accelerate materials discovery, computational methods such as inverse materials design, are us... more To accelerate materials discovery, computational methods such as inverse materials design, are used to design UV-absorbing coronene based derivatives that, following synthesis achieve high open-circuit voltages and visible transparencies.

Chemistry – A European Journal

Chemical Science

trans-Linked 3D-semiconductors have higher intramolecular conductivity.

Journal of the American Chemical Society

Accounts of Chemical Research

Nature communications, Jan 16, 2018

Self-assembly of electroactive molecules is a promising route to new types of functional semicond... more Self-assembly of electroactive molecules is a promising route to new types of functional semiconductors. Here we report a capsule-shaped molecule that assembles itself into a cellular semiconducting material. The interior space of the capsule with a volume of ~415 Å is a nanoenvironment that can accommodate a guest. To self-assemble these capsules into electronic materials, we functionalize the thiophene rings with bromines, which encode self-assembly into two-dimensional layers held together through halogen bonding interactions. In the solid state and in films, these two-dimensional layers assemble into the three-dimensional crystalline structure. This hollow material is able to form the active layer in field effect transistor devices. We find that the current of these devices has strong response to the guest's interaction within the hollow spaces in the film. These devices are remarkable in their ability to distinguish, through their electrical response, between small differen...

Journal of the American Chemical Society, Oct 5, 2016

Here, we compare analogous cyclic and acyclic π-conjugated molecules as n-type electronic materia... more Here, we compare analogous cyclic and acyclic π-conjugated molecules as n-type electronic materials and find that the cyclic molecules have numerous benefits in organic photovoltaics. This is the first report of such a direct comparison. We designed two conjugated cycles for this study. Each comprises four subunits: one combines four electron-accepting, redox-active, diphenyl-perylenediimide subunits, and the other alternates two electron-donating bithiophene units with two diphenyl-perylenediimide units. We compare the macrocycles to acyclic versions of these molecules and find that, relative to the acyclic analogs, the conjugated macrocycles have bathochromically shifted UV-vis absorbances and are more easily reduced. In blended films, macrocycle-based devices show higher electron mobility and good morphology. All of these factors contribute to the more than doubling of the power conversion efficiency observed in organic photovoltaic devices with these macrocycles as the n-type, e...

Journal of the American Chemical Society, Dec 21, 2016

Organic photodetectors (OPDs) are attractive for their high optical absorption coefficient, broad... more Organic photodetectors (OPDs) are attractive for their high optical absorption coefficient, broad wavelength tunability, and compatibility with lightweight and flexible devices. Here we describe a new molecular design that enables high performance organic photodetectors. We use a rigid, conjugated macrocycle as the electron acceptor in devices to obtain high photocurrent and low dark current. We make a direct comparison between the devices made with the macrocyclic acceptor and an acyclic control molecule; we find that the superior performance of the macrocycle originates from its rigid, conjugated, and cyclic structure. The macrocycle's rigid structure reduces the number of charged defects originating from deformed sp(2) carbons and covalent defects from photo/thermoactivation. With this molecular design, we are able to suppress dark current density while retaining high responsivity in an ultrasensitive nonfullerene OPD. Importantly, we achieve a detectivity of ∼10(14) Jones at...

ACS Central Science, 2015

Colin Nuckolls describes the importance of D−A systems within nanohoops as reported by Darzi et a... more Colin Nuckolls describes the importance of D−A systems within nanohoops as reported by Darzi et al. and others.

Accounts of chemical research, Jan 17, 2015

Conspectus This Account describes a body of research in the design, synthesis, and assembly of mo... more Conspectus This Account describes a body of research in the design, synthesis, and assembly of molecular materials made from strained polycyclic aromatic molecules. The strain in the molecular subunits severely distorts the aromatic molecules away from planarity. We coined the term "contorted aromatics" to describe this class of molecules. Using these molecules, we demonstrate that the curved pi-surfaces are useful as subunits to make self-assembled electronic materials. We have created and continue to study two broad classes of these "contorted aromatics": discs and ribbons. The figure that accompanies this conspectus displays the three-dimensional surfaces of a selection of these "contorted aromatics". The disc-shaped contorted molecules have well-defined conformations that create concave pi-surfaces. When these disc-shaped molecules are substituted with hydrocarbon side chains, they self-assemble into columnar superstructures. Depending on the hydroc...

Journal of the American Chemical Society, Jan 12, 2015

We present here a new design motif for strained, conjugated macrocycles that incorporates two dif... more We present here a new design motif for strained, conjugated macrocycles that incorporates two different aromatics into the cycle with an -A-B-A-B- pattern. In this study, we demonstrate the concept by alternating electron donors and acceptors in a conjugated cycle. The donor is a bithiophene, and the acceptor is a perylene diimide derivative. The macrocycle formed has a persistent elliptiform cavity that is lined with the sulfur atoms of the thiophenes and the π-faces of the perylene diimide. Due to the linkage of the perylene diimide subunits, the macrocycles exist in both chiral and achiral forms. We separate the three stereoisomers using chiral high-performance liquid chromatography and study their interconversion. The mechanism for interconversion involves an "intramolecular somersault" in which one of the PDIs rotates around its transverse axis, thereby moving one of its diimide heads through the plane of the cavity. These unusual macrocycles are black in color with a...