Bridging the Fields of Solar Cell and Battery Research to Develop High-Performance Anodes for Photoelectrochemical Cells and Metal Ion Batteries

Abstract

Solar-to-electricity energy conversion and large scale electricity storage technologies are key to achieve a sustainable development of society. For energy conversion, photoelectrochemical solar cells were proposed as an economic alternative to the conventional Si-based technology. For energy storage, metal-ion batteries are a very promising technology. Titania (TiO 2 ) based anodes are widely used in photoelectrochemical cells and have recently emerged as safe, high-rate anodes for metal-ion batteries. In both applications, titania interacts with electrolyte species: molecules and metal ions. Details of this interaction determine the performance of the electrode in both technologies, but no unified theoretical description exists, e.g., there is no systematic description of the effects of Li, Na insertion into TiO 2 on solar cell performance (while it is widely studied in battery research) and no description of effects of surface adsorbents on the performance of battery anodes (while they are widely studied in solar cell research). In fact, there is no systematic description of interactions of electrolyte species with TiO 2 of different phases and morphologies. We propose a computation-focused study that will bridge the two fields that have heretofore largely been developing in parallel and will identify improved anode materials for both photoelectrochemical solar cells and metal-ion batteries. OPEN ACCESSChallenges 2013, 4 117

Co-Adsorbent Effect on the Sensitization of TiO2 and ZnO Surfaces: A Theoretical Study

“…In particular, we investigate the attachment of a recently proposed organic dye, named hemisquaraine (CT1), 10,11 to anatase-TiO 2 and ZnO surfaces in the presence of the simplest nitrogen-containing heterocyclic molecule, imidazole, proposed as co-adsorbent. 12 Our results show that the co-adsorbent strengthens the binding between the dye and the metal oxide surface and correspondingly shifts the dye molecular orbitals to lower energies and the metal oxide valence band (VB) and CB to higher energies. The observed shifts change the relative energy alignments of the heterostructure either giving rise to a different type of energy alignment (straddling, staggered, or broken gap) or to modifications of the V oc (larger or smaller).…”

“…Herein, the co-adsorbent effects on the photovoltaic performances of DSSCs are discussed by means of a theoretical study based on density functional theory for a prototype organic/inorganic system. In particular, we investigate the attachment of a recently proposed organic dye, named hemi-squaraine (CT1), , to anatase-TiO 2 and ZnO surfaces in the presence of the simplest nitrogen-containing heterocyclic molecule, imidazole, proposed as co-adsorbent . Our results show that the co-adsorbent strengthens the binding between the dye and the metal oxide surface and correspondingly shifts the dye molecular orbitals to lower energies and the metal oxide valence band (VB) and CB to higher energies.…”

Achieving Improved Solar Absorbance of Small Organic Dyes Featuring Quinoidized Five-Membered Heterocycles

“…However, phenothiazine dyes reported in the literature [7,[20][21][22][23][24], including the dye that served as a prototype for this study [7], have large kinetic redundancy for injection (with driving forces of the order of 1 eV), so that LUMO stabilization is desired to lower the excited state energy and therewith lower thermal losses [2,[21][22][23][24]. The conduction band minimum of TiO 2 can also be modulated by functionalizing its surface with molecules or atomic ions [25,26]. A selenophene dye can be chosen to slightly increase the LUMO energy (Table I).…”