Auger Up-Conversion of Low-Intensity Infrared Light in Engineered Quantum Dots

Area of Science:

• Materials Science
• Nanotechnology
• Photovoltaics

Background:

• Photovoltaic cells lose efficiency due to transparency to sub-band-gap solar photons.
• Up-conversion processes, like nonlinear two-photon absorption (2PA) and triplet fusion, aim to utilize these photons but face efficiency and implementation challenges.

Purpose of the Study:

• To investigate Auger up-conversion in PbSe/CdSe core-shell quantum dots as a method to improve solar cell efficiency.
• To demonstrate the advantages of this approach over traditional up-conversion techniques.

Main Methods:

• Utilized thick-shell PbSe/CdSe quantum dots for Auger up-conversion.
• Studied Auger recombination where two core-based excitons generate a shell-based exciton.
• Characterized enhanced absorption cross-sections and exciton lifetimes in heterostructures.

Main Results:

• PbSe/CdSe quantum dots exhibit Auger up-conversion with effective cross-sections over 6 orders of magnitude higher than nonlinear 2PA.
• Achieved efficient up-conversion of continuous wave infrared light at low intensities (few W/cm²).
• Tailored heterostructures showed improved absorption, efficient Auger pathways, and longer exciton lifetimes.

Conclusions:

• Auger up-conversion in PbSe/CdSe quantum dots effectively addresses limitations of conventional up-conversion methods.
• This technology offers a promising pathway for significantly improving solar energy conversion efficiency.