Transient Electrical Response of Dye-Sensitized ZnO Nanorod Solar Cells

Abstract

A dye-sensitized solar cell was build with an electrode consisting of ZnO nanorods with a mean diameter of 80 nm instead of the commonly used nano colloidal TiO2 substrate. The electrical response of the cell under excitation with an alternating current (AC) voltage source was measured and analyzed in a wide frequency range (40 Hz−110 MHz). The results were compared to time-resolved measurements of the photocurrent generated by a nanosecond pulsed light source. Both measurements could be described by the same electrical equivalent circuit that consisted of passive circuit elements only. The slow response of the cell in the ms time range is mainly caused by the large space charge capacitance of the ZnO nanorod electrode. Because of the low impedance of the nanorod electrode, the photo response and the AC response is also influenced by the electrical properties of other interfaces in the cell, such as the counterelectrode. Thus the signal is more complex than the single RC response usually observed for planar photo anodes. SPICE simulations of the photocurrent response are given to illustrate the influence of the different interfaces on the overall signal. The differences observed in the electrical behavior of the Grätzel cell and the ZnO equivalent are discussed.

Quantum‐Dot‐Sensitized Solar Cells

“…[55,56] For DSCs based on ZnO nanorods it was shown that the doping density can be sufficiently high to generate substantial band bending within larger rods, such that the photovoltage is partly generated by electrons accumulating in the space-charge layer at the nanorod surface. [57] For QDSCs there has been substantially less discussion regarding their working principle, and many conclusions reached for DSCs are applicable to QDSCs. However, the much wider variety of materials used for QDSCs including aqueous electrolytes, structural differences such as QD coverage of less than a monolayer and the lack of ideal counter electrodes for certain electrolytes must be considered to understand the working principle of a specific QDSC configuration.…”

Physical electrochemistry of nanostructured devices

“…Carrier densities of 10 19 cm À3 have also been found for the ZnO nanorods prepared by chemical bath. 117 …”

Effect of water content on growth and optical properties of ZnO nanoparticles generated in binary solvent mixtures by micro-continuous flow synthesis

“…During the past few years, nanocrystals of zinc oxide have attracted a lot of interest due to their potential applications, such as solar cells [1][2][3], photocatalysts [4,5], luminescent materials [6,7], gas sensors [8][9][10] and so on. Different technologies have been developed to synthesize ZnO nanocrystals with different shapes and sizes, including hydrothermal synthesis [11,12], sol-gel method [13][14][15], thermal decomposition [16,17], microwave irradiation method [18][19][20], chemical vapor deposition [21,22], and continuous flow techniques [23,24].…”