ZnO Nanostructures for Dye‐Sensitized Solar Cells

Abstract

This Review focuses on recent developments in the use of ZnO nanostructures for dye‐sensitized solar cell (DSC) applications. It is shown that carefully designed and fabricated nanostructured ZnO films are advantageous for use as a DSC photoelectrode as they offer larger surface areas than bulk film material, direct electron pathways, or effective light‐scattering centers, and, when combined with TiO2, produce a core–shell structure that reduces the combination rate. The limitations of ZnO‐based DSCs are also discussed and several possible methods are proposed so as to expand the knowledge of ZnO to TiO2, motivating further improvement in the power‐conversion efficiency of DSCs.

One-dimensional ZnO nanostructures: Solution growth and functional properties

“…Compared with other solar cells, DSSCs have relatively high efficiency under weak light illumination, so they can be used for internal applications, such as in laptops and mobile phones [466]. The low efficiency of ZnO-based DSSCs probably arises for four reasons: the accumulation of stable Zn 2+ /dye complexes instead of chemisorption of the dye molecule on ZnO [463]; the low electron injection efficiency induced by the energy level mismatch between the lowest unoccupied molecular orbital (LUMO) of the dye and the photoanode conduction band minimum; the dye regeneration efficiency induced by energy level mismatch between the highest occupied molecular orbital (HOMO) of the dye and the redox mediator potential in the electrolyte [458,463]; the high carrier recombination rate due to the defect surface trap states of ZnO nanowires [467], which can be decreased by coating with TiO 2 , Al 2 O 3 , or ZrO 2 passivating shells [222,468].…”

Interpenetrating heterojunction photovoltaic cells based on C60 nano-crystallized thin films

“…All of the C 60 films that were treated with solvent spin-coating or SVA exhibited an increase in absorption intensity between 300 to 500 nm compared to the untreated films. This absorption increase was caused by light scattering from the nanocrystals [32,33], and increase crystallinity of nanocrystallized C 60 films [34]. The UV-Vis absorption of the film subjected to SVA with n-C 6 H 14 changed significantly.…”

New generation solar cells: concepts, trends and perspectives

“…Another important feature was its high electron mobility. A number of other oxides, such as ZnO, 114 SnO 2 , 115 and Nb 2 O 5 , 116 have been tested as alternatives, but TiO 2 has overall given the highest efficiencies by far, which is why it is still the most commonly used metal semiconductor. In a different aspect, one of the fundamental strategies to enhance light-harvesting, is by achieving panchromatic absorption through co-sensitization with dyes possessing complementary optical properties.…”