(I) Computing excited states of chromophores in water with time-dependent density functional theory (TDDFT) can be notoriously difficult due to the presence of charge-transfer transitions and the unknown convergence of excited state properties with the amount of explicit solvent.  My results address both of these issues by examining chromophore/water energy levels with various density functionals in various environments (explicit solvent, continuum, point charges, and vacuum) and determining the amount of explicit solvent necessary for computing converged excitation energies for different chromophore solutes.(II) Nanocarbon based photovoltaics offer a promising new architecture for the next generation of solar cells. I will describe a new nanocarbon active layer material that involves fullerene acceptors adsorbed along the length of single-walled carbon nanotubes, surrounded by a graphene nanoribbon. Our work demonstrates for the first time that a key factor determining the efficiency of single-walled carbon nanotube (SWCNT)/fullerene devices is the chirality of the SWCNT. This is shown via current density vs voltage measurements of nanocarbon devices prepared with (9,7), (7,6) and (6,5) SWCNTs, as well as DFT density of states calculations of C60 adsorbed onto the corresponding SWCNTs.  The trends in efficiency are rationalized in terms of the relative energies of the fullerene and SWCNT conduction band energy levels.

Computing excited states in aqueous solution and nanocarbon photovoltaics: Chirality is key to efficiency

246th National Meeting (2013)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.