title: Mesoscale modeling of photoelectrochemical devices: light absorption and carrier collection in monolithic, tandem, Si|WO3 microwires.
abstract: We analyze mesoscale light absorption and carrier collection in a tandem junction photoelectrochemical device using electromagnetic simulations. The tandem device consists of silicon (E(g,Si) = 1.1 eV) and tungsten oxide (E(g,WO3) = 2.6 eV) as photocathode and photoanode materials, respectively. Specifically, we investigated Si microwires with lengths of 100 µm, and diameters of 2 µm, with a 7 µm pitch, covered vertically with 50 µm of WO3 with a thickness of 1 µm. Many geometrical variants of this prototypical tandem device were explored. For conditions of illumination with the AM 1.5G spectra, the nominal design resulted in a short circuit current density, J(SC), of 1 mA/cm(2), which is limited by the WO3 absorption. Geometrical optimization of photoanode and photocathode shape and contact material selection, enabled a three-fold increase in short circuit current density relative to the initial design via enhanced WO3 light absorption. These findings validate the usefulness of a mesoscale analysis for ascertaining optimum optoelectronic performance in photoelectrochemical devices.
authors.forename: Katherine T
authors.initials: KT
authors.lastname: Fountaine
authors.forename: Harry A
authors.initials: HA
authors.lastname: Atwater
mesh_terms: D065638:Absorption, Radiation; D003198:Computer Simulation; D004553:Electric Conductivity; D004579:Electron Transport / Q000528:radiation effects; D008027:Light; D008956:Models, Chemical; D053761:Nanocomposites / Q000737:chemistry* / Q000648:ultrastructure; D053770:Nanowires / Q000737:chemistry* / Q000528:radiation effects / Q000648:ultrastructure; D010087:Oxides / Q000737:chemistry* / Q000528:radiation effects; D012542:Scattering, Radiation; D012666:Semiconductors; D012825:Silicon / Q000737:chemistry* / Q000528:radiation effects; D014414:Tungsten / Q000737:chemistry* / Q000528:radiation effects
chemical_list: D010087:Oxides; C511604:tungsten oxide; D014414:Tungsten; D012825:Silicon