Semiconductor hierarchically structured flower-like clusters for dye-sensitized solar cells with nearly 100% charge collection efficiency

Abstract

By combining the ease of producing ZnO nanoflowers with the advantageous chemical stability of TiO₂, hierarchically structured hollow TiO₂ flower-like clusters were yielded via chemical bath deposition (CBD) of ZnO nanoflowers, followed by their conversion into TiO₂ flower-like clusters in the presence of TiO₂ precursors. The effects of ZnO precursor concentration, precursor amount, and reaction time on the formation of ZnO nanoflowers were systematically explored. Dye-sensitized solar cells fabricated by utilizing these hierarchically structured ZnO and TiO₂ flower clusters exhibited a power conversion efficiency of 1.16% and 2.73%, respectively, under 100 mW cm⁻² illumination. The intensity modulated photocurrent/photovoltage spectroscopy (IMPS/IMVS) studies suggested that flower-like structures had a fast electron transit time and their charge collection efficiency was nearly 100%.