A thin-film polycrystalline photoelectrochemical cell with 8% solar conversion efficiency

Abstract

Photoelectrochemical solar cells (PECs) may become an economic method for conversion of light to electricity, due largely to the simplicity of formation, and quality, of the poly-crystalline semiconductor–electrolyte junction. Within the past few years, conversion efficiencies of thin-layer poly crystalline-based cells have increased from ∼1% to a recently reported 7.3% for the n-GaAs/Se_x²⁻ system¹. PECs based on the CdSe–polysulphide system have been studied extensively recently. CdTe, with a band-gap, E_g, ∼1.45 eV is better matched to the solar spectrum than CdSe (E_g∼1·75 eV), but is unstable in polysulphide solutions as a photoanode at the current densities to be expected under normal solar irradiation (>10 mA cm⁻²). A poly sulphide-based PEC is described here which uses poly-crystalline layers of CdSe_0.65Te_0.35, electrodes of which are prepared by painting a slurry of the semiconductor onto a T1 substrate, and sintering. Subsequent surface treatments of these layers lead to a solar-to-electrical conversion efficiency of up to 8%, with stability comparable to the thin-layer polycrystalline CdSe/polysulphide system².