jp5b00295_si_001.pdf (2.8 MB)
Constructing Multifunctional Virus-Templated Nanoporous Composites for Thin Film Solar Cells: Contributions of Morphology and Optics to Photocurrent Generation
journal contribution
posted on 2015-06-25, 00:00 authored by Noémie-Manuelle Dorval Courchesne, Matthew T. Klug, Kevin
J. Huang, Mark C. Weidman, Victor J. Cantú, Po-Yen Chen, Steven E. Kooi, Dong Soo Yun, William A. Tisdale, Nicholas
X. Fang, Angela M. Belcher, Paula T. HammondBiotemplates, such as the high aspect
ratio M13 bacteriophage,
can be used to nucleate noble metal nanoparticles and photoactive
materials such as metal oxides, as well as organize them into continuous
structures. Such attributes make them attractive scaffolds for solar
applications requiring precise organization at the nanoscale. For
instance, thin film solar cells benefit from nanostructured morphologies
that aid light absorption and carrier transport. Here, we present
a biotemplating strategy for assembling nanostructured thin film solar
cells that enhance the generated photocurrent through two features:
(1) a nanoporous and continuous M13 bacteriophage-templated titania
network that improves charge collection and (2) the incorporation
of metal nanoparticles within the active layer of the device to improve
light harvesting. We demonstrate our ability to construct virus-templated
solar cells by applying this strategy to depleted titania–lead
sulfide quantum dot (PbS QD) bulk heterojunctions. The titania morphology
produced by our biotemplate allows charges to be efficiently collected
from the bulk of the active material and light that is otherwise poorly
absorbed by the QDs to be harvested using metal nanoparticles that
exhibit plasmon resonances in the visible range. We show that high
aspect ratio bacteriophages provide a structural template for synthesizing
titania networks with tunable porosity, into which PbS QDs are infiltrated
to create photoactive nanocomposites suitable for photovoltaics. Upon
optimization, the generated photocurrent and power conversion efficiency
of the bacteriophage-templated devices demonstrate a 2-fold improvement
over those of control devices made with randomly organized titania
nanoparticles. When the virus is complexed with gold nanoparticles
(Au NPs), silver nanoparticles (Ag NPs), or silver nanoplates (Ag
NPLs) during assembly, the device performance is further improved,
with Ag NPLs enhancing the short-circuit current density and power
conversion efficiency by 16% and 36.5%, respectively, over those of
virus-based devices without NPs. The observed trends in photocurrent
enhancement match well with numerical predictions, and the role of
the nanostructured morphology on the device optics was computationally
explored. The challenges overcome in this work could be extended to
other heterojunction devices, such as hybrid systems involving conducting
polymers, as well as other biologically templated electronics.