COLL 22 |
We
report a quantum-dot-sensitized solar cell which combines CdSe quantum dots
adsorbed on ZnO nanowires to convert light into electrical current flow. Specifically,
an array of ZnO nanowires were grown vertically on a transparent conducting
glass substrate in aqueous solutions of methenamine and zinc nitrate. CdSe
quantum dots were synthesized separately and capped with mercaptopropionic
acid. Following, the quantum dots were attached to the surface of the nanowires
to form a photosensitized anode where the ZnO nanowire surfaces were decorated
with a monolayer of CdSe quantum dots. A platinized transparent conducting oxide photocathode and
the nanowire photoanode were positioned face-to-face and the space between the
anode and the cathode was filled with an electrolyte. When
illuminated with visible light, the excited CdSe quantum dots injected
electrons across the quantum dot-nanowire interface in to the ZnO nanowire. The
morphology of the nanowires then provided the photoinjected electrons with a
direct electrical pathway to the transparent conducting oxide anode. These solar cells exhibited
short-circuit currents ranging from 1–2 mA/cm2 and
open-circuit voltages of ~0.6 V when illuminated with 100 mW/cm2
simulated AM1.5 spectrum. The internal quantum efficiency (IQE) of this QDSSC in the
spectral range covering the first excitonic transition (~500–600 nm) was
50–60%.
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Interfacial Electron Transfer and Solar Energy Conversion: From Molecules to Nanomaterials
8:20 AM-12:00 PM, Sunday, April 6, 2008 Morial Convention Center -- Rm. 226, Oral
Division of Colloid & Surface Chemistry |