Photovoltaic Conversion Enhancement of CdSe Quantum Dot-Sensitized TiO2 Decorated with Au Nanoparticles and P3OT

By Zarazúa, I.; De la Rosa, E.; López-Luke, T.; Reyes-Gomez, J.; Ruiz, S.; Ã?ngeles Chavez, C. & Zhang, Jin Z.
Published in The Journal of Physical Chemistry C NULL 2011

Abstract

Novel composite titanium dioxide (TiO2) films of 10 μm thickness were prepared and characterized with an emphasis on evaluating their photovoltaic properties. The films contained 13 nm TiO2 nanocrystals (NCs) with anatase crystalline phase deposited on FTO substrates, composited with CdSe quantum dots (QDs), gold nanoparticles (Au NPs), and poly(3-octylthiophene) (P3OT) in different configurations and combinations. With the introduction of Au NPs or P3OT into the TiO2/QDs films, the photocurrent increased to ∼85% and ∼150%, respectively, while the photoconversion efficiency increased by ∼167% and ∼177%, respectively. An interesting synergistic effect was observed when Au NPs and P3OT were used in conjunction. The configuration of TiO2/Au/QDs/P3OT film exhibited a photocurrent of 906 μA (an enhancement of ∼285%) and a photoconversion efficiency of 0.661% (an enhancement of ∼600%) compared to that of TiO2/QDs films. Such significant enhancement is attributed to the ability of the Au NPs to facilitate charge separation and improve electron injection as well as P3OT's ability to inject electrons and enhance hole transport. These properties, when combined with the QD's strong photoabsorption in the visible, led to the overall increase in photocurrent generation, fill factor, and consequently photoconversion efficiency.

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