1 Introduction Global energy demand is predicted to exceed 30 TW by 2050, about double the present value [1]. This predicament, known as the TeraWatt challenge, and concern over anthropogenic climate change, resource availability ("peak energy") and energy security have all increased the interest in renewable energy (hydroelectric, wind, solar, geothermal and biomass) [2]. One of the most promising renewable energy technologies is solar photovoltaics (PV) which convert sunlight directly into electrical energy. Although the resource potential of PV is enormous, it currently constitutes a small fraction (<1%) of global energy supply [2]. One of the main factors limiting the widespread adoption of PV is its low energy density, low efficiency, and relatively high cost in comparison to other energy technologies. This means that current PV technology can only compete in areas of high insolation or by government incentives such as feed-in tariff programs.One of the most relevant metrics for PV devices is the power conversion efficiency (PCE); that is, the efficiency with which sunlight can be converted to electrical power. A significant effort in PV research today aims to improve PCE while simultaneously reducing (or, at least, not significantly impacting) production cost. The vast majority of