Sensitization of TiO<sub>2</sub> with PbSe Quantum
Dots by SILAR: How Mercaptophenol Improves Charge Separation
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Abstract
The use of PbSe quantum dots (QDs) as sensitizers for
TiO<sub>2</sub> samples has been primarily hampered by limitations
on charge injection.
Herein, a novel successive ionic layer adsorption and reaction (SILAR)
method, allowing for an intimate TiO<sub>2</sub>/PbSe contact and
a strong quantum confinement, is described. Photoelectrochemical experiments
and transient absorption measurements reveal that charge separation
indeed occurs when using either aqueous sulfite or <i>spiro</i>-OMeTAD as a hole conductor and that it can be further enhanced by
attaching <i>p</i>-mercaptophenol (MPH) to the QD surface.
These results suggest that MPH can promote an efficient funneling
of the photogenerated holes from the PbSe to the hole scavenging medium,
thereby increasing the yield of electron injection into TiO<sub>2</sub>. In a more general vein, this work paves the way for the fabrication
of PbSe-sensitized solar cells, emphasizing the importance of controlling
the QD/hole scavenger interface to further boost their conversion
efficiency