Effects of dye adsorption on the electron transport properties in ZnO-nanowire dye-sensitized solar cells

Abstract

Mercurochrome and N3 dyes are employed to be the sensitizers in the ZnO-nanowire ͑NW͒ dye-sensitized solar cells ͑DSSCs͒. A lower fill factor is obtained in the N3-sensitized cell which results in comparable efficiencies in both ZnO-NW DSSCs although the N3 molecules possess a wider absorptive range for light harvesting. Electrochemical impedance spectroscopy and open-circuit photovoltage decay measurements are employed to investigate the electron transport properties in both ZnO-NW DSSCs. The results indicate that more abundant electron interfacial recombination occurs in the N3-sensitized ZnO-NW DSSC due to the higher surface trap density in the ZnO-NW photoanode after N3 dye adsorption.

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].…”

Efficiency Investigation of Dye-Sensitized Solar Cells Based on the Zinc Oxide Nanowires

“…In recent years,due to their unique optical, chemical, electrical and piezoelectric properties, ZnO nano structures have become very common in semiconductor devices [8][9][10][11][12][13][14] . ZnO nano wires in a dye-sensitized solar cell create a direct electron path way which leads to an increase in electron diffusion length and life time.Several methods such as vapor-liquid-solid, metal-organic chemical vapor deposition and thermal evaporation 6,17 have been introduced in order to grow a high quality ZnO nanostructure array at high temperatures.…”

Facile construction of nanofibrous ZnO photoelectrode for dye-sensitized solar cell applications

“…8 Up to date, photoelectrodes based on ZnO nanowires, nanorods, and nanotubes have been prepared by various techniques, with energy conversion efficiency of 0.5%-1.6%. [9][10][11] Alternatively, electrospinning technique has also provided a simple and cost-effective way to prepare semiconductor oxide with 1D nanostructure. 12 However, the application of electrospun nanofibers in DSSC is limited by the poor adhesion of electrospun nanofibers to the FTO substrate.…”