Electron Transport in Dye-Sensitized Solar Cells Based on ZnO Nanotubes: Evidence for Highly Efficient Charge Collection and Exceptionally Rapid Dynamics

Abstract

Dye-sensitized solar cells based on ordered arrays of polycrystalline ZnO nanotubes, 64 µm in length, are shown to exhibit efficient electron collection over the entire photoanode array length. Electrochemical impedance spectroscopy, open-circuit photovoltage decay analysis, and incident-photon-to-current efficiency spectra are used to quantify charge transport and lifetimes. Despite the relatively thick photoanode, the charge extraction time is found to be faster than observed in traditional TiO 2 nanoparticle photoanodes. If the extraction dynamics are interpreted as diffusive, effective electron diffusion coefficients of up to 0.4 cm 2 s -1 are obtained, making these pseudo-1D photoanodes the fastest reported for an operating DSC to date. Rapid electron collection is of practical significance because it should enable alternative redox shuttles, which display relatively fast electron-interception dynamics, to be employed without significant loss of photocurrent.

Strong Efficiency Improvements in Ultra‐low‐Cost Inorganic Nanowire Solar Cells

“…This is achieved in inset (ii) of Figure 1 b by coating the semiconducting layers on a supporting nanostructure, a strategy that has been employed in dyesensitized solar cells. [ 19 ] Alternatively, the semiconductors can be directly nanostructured, as illustrated in inset (iii). A variety of semiconducting nanowire and nanotube morphologies have been used to improve charge collection in hybrid organicinorganic, [ 11 , 20 ] dye-sensitized, [ 21 ] extremely thin absorber, [ 22 ] and inorganic solar cells (Si, [ 23 , 24 ] CdS-CdTe, [ 25 ] PbSe quantum dots, [ 26 ] GaAs [ 27 ] ).…”

SYNERGISTIC EFFECT OF SURFACE PLASMON RESONANCE AND CONSTRUCTED THREE-DIMENSIONAL INTERWOVEN STRUCTURED TiO2 PHOTOANODE FOR DYE-SENSITIZED SOLAR CELLS

“…The Nyquist diagrams of both DSSCs exhibit three semicircles. [21][22][23][24] The¯rst arc in the high-frequency region (10 3 -10 5 Hz) is attributed to the impedance caused by the charge-transfer process at the counter electrode/electrolyte interface, and the second arc in the low frequency region (1-10 3 Hz) is attributed to the charge transfer at the TiO 2 /electrolyte interface. The third arc at lower frequencies is ascribed to Nernst di®usion within the electrolyte.…”

Trends, Challenges and Opportunities in Advanced Solar Cells Technologies and PV Market

“…(iii) The electroluminescence that occurs due to the nanostructured regions is simulated and discussed [16]. [23]. A suitable film thickness of 10-50 μm for TiO 2 layer was found in a way in which both J sc and η are decreasing with the increasing of thickness [24,25].…”