Fabrication of ZnO/Absorber Heterostructures for Nanostructured Solar Cells

Abstract

The development of low-band-gap semiconducting materials for the extremely thin absorber (eta) solar cell using cheap and scalable methods is the main objective of this work. The eta-solar cell is composed of all inorganic materials consisting of an extremely thin layer of absorbing material (1.1 < Eg < 1.8 eV) sandwiched between nanostructured transparent electron and hole conductors (Eg ≥ 3.3 eV). The photosensitization of the electrodeposited ZnO nanowires with conformal layers of CdS and CdSe prepared by successive ionic layer adsorption and reaction (SILAR) is proposed. The improvement of the absorber structural and optical properties by annealing and chemical treatment is achieved. SILAR method insures a conformal layer formation on the entire nanowire surface. Thus prepared heterostructures exhibit optimal optical features. The effects of the core/shell heterostructure interface (ZnO/absorber) were studied in a photoelectrochemical cell using the 3I-/I3- redox electrolyte as in a standard DSSC. The effects of the chemical treatment and annealing step of the photosensitizing shell are studied.