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Enhanced multiple exciton generation in quasi-one-dimensional semiconductors
Paul D Cunningham1, Janice E Boercker, Edward E Foos
1U.S. Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, D.C. 20375, United States. paul.cunningham.ctr@nrl.navy.mil
Nano Letters
|July 20, 2011
Summary
Multiple exciton generation (MEG) in lead selenide (PbSe) nanorods significantly boosts optoelectronic device efficiency. This breakthrough in semiconductor nanostructures approaches the theoretical limit for enhanced solar energy conversion.
Area of Science:
- Optoelectronics and Nanotechnology
- Materials Science and Engineering
Background:
- Single exciton generation per photon limits photodetector and photovoltaic cell efficiency.
- Multiple exciton generation (MEG) in semiconductor nanostructures offers a pathway to overcome this limitation.
- MEG efficiency and threshold energy are crucial parameters for device performance.
Purpose of the Study:
- To investigate and enhance multiple exciton generation (MEG) in lead selenide (PbSe) nanostructures.
- To compare MEG in quasi-one-dimensional PbSe nanorods versus zero-dimensional PbSe nanocrystals.
- To assess the impact of enhanced MEG on photovoltaic cell performance.
Main Methods:
- Fabrication and characterization of PbSe quasi-one-dimensional nanorods and zero-dimensional nanocrystals.
- Spectroscopic analysis to quantify MEG efficiency and threshold energy.
- Fabrication and testing of photovoltaic cells utilizing PbSe nanorods.
Main Results:
- PbSe nanorods exhibit significantly enhanced MEG compared to PbSe nanocrystals.
- MEG efficiency in nanorods is approximately doubled relative to nanocrystals.
- The threshold energy for MEG in nanorods is reduced to (2.23 ± 0.03)E(g), nearing the theoretical 2E(g) limit.
- Photovoltaic cells incorporating PbSe nanorods demonstrate improved power conversion efficiencies.
Conclusions:
- Quasi-one-dimensional PbSe nanorods are superior to zero-dimensional nanocrystals for achieving efficient multiple exciton generation.
- Enhanced MEG in PbSe nanorods leads to improved photovoltaic device performance, especially with solar concentrators.
- This research advances the potential of nanostructured materials for next-generation solar energy technologies.
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