Stibnite Sensitized Hollow Cubic TiO2 Photoelectrodes for Organic-Inorganic Heterojunction Solar Cells

Abstract

Enhancing power conversion efficiency in organic-inorganic heterojunction solar cells faces several serious hurdles. Although standard TiO2 nanoparticles-based heterojunction solar cells are moderately efficient, the TiO2 nanostructure has several drawbacks including a disordered low surface area with poor pore structure. Thus, it is necessary to develop a new TiO2 morphology for effective photon harvesting in organic-inorganic heterojunction solar cells. Hollow nanostructured electrodes are widely used in energy related devices because of their high surface area, larger pores, and superior light scattering properties. Here, we report the first successful application of hollow cubic TiO2 (HCT) nanostructured photoelectrodes sensitized with stibnite for all solid-state heterojunction solar cells. The unique hollow nanostructure resolved several issues of organic-inorganic heterojunction solar cells, such as insufficient pore size for inorganic sensitizers, large grain boundary area, and poor penetration of organic hole conductors, thereby improving the cell efficiency. Device performance was strongly dependent on the thickness of stibnite, which could be controlled by deposition time. Devices optimized with HCT exhibited a high solar to power conversion efficiency (∼3.5%), which was slightly higher than the TiO2 nanoparticle-based devices.