CdS Nanowire
Solar Cells: Dual Role of Squaraine Dye
as a Sensitizer and a Hole Transporter
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Abstract
The squaraine dye (SQ) anchored onto
CdS nanowires serves as a
photosensitizing dye and a hole acceptor. This dual role of the squaraine
dye has been successfully exploited in a nanowire solar cell to improve
the photoconversion efficiency. Electrophoretic deposition of CdS
NWs and CdS NWs+SQ composite onto conducting glass electrodes was
performed to obtain robust photoanodes and evaluate the photovoltaic
performance of nanowire solar cells (NWSCs). Whereas the sensitization
property of the SQ extends the response of CdS NWSCs into the near-IR
(NIR) region, its redox property facilitates shuttling of holes to
the electrolyte and suppressing the charge recombination process.
Transient absorption measurements confirm the formation of cation
radical of the dye arising from these two processes. The dual role
of the squaraine dye has enabled us to improve the power conversion
efficiency of NWSCs by a factor of ∼20. Photoelectrochemical,
spectroelectrochemical, and spectroscopic measurements provide insight
into the multifaceted role of squaraine dye in improving the performance
of NWSCs