PbS-Quantum-Dot-Based Heterojunction Solar Cells Utilizing
ZnO Nanowires for High External Quantum Efficiency in the Near-Infrared
Region
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Abstract
The improvement of solar cell performance
in the near-infrared
(near-IR) region is an important challenge to increase power conversion
efficiency under one-sun illumination. PbS quantum-dot (QD)-based
heterojunction solar cells with high efficiency in the near-IR region
were constructed by combining ZnO nanowire arrays with PbS QDs, which
give a first exciton absorption band centering at wavelengths longer
than 1 μm. The morphology of ZnO nanowire arrays was systematically
investigated to achieve high light-harvesting efficiency as well as
efficient carrier collection. The solar cells with the PbS QD/ZnO
nanowire structures made up of densely grown thin ZnO nanowires about
1.2 μm long yielded a maximum incident-photon-to-current conversion
efficiency (IPCE) of 58% in the near-IR region (@1020 nm) and over
80% in the visible region (shorter than 670 nm). The power conversion
efficiency obtained on the solar cell reached about 6.0% under simulated
one-sun illumination