Efficiently Passivated PbSe Quantum Dot Solids for Infrared Photovoltaics

Area of Science:

• Materials Science
• Nanotechnology
• Photovoltaics

Background:

• Infrared (IR) solar cells offer improved efficiency by capturing low-energy IR photons.
• Lead selenide (PbSe) quantum dots (QDs) are excellent IR absorbers but suffer from high trap-state density due to poor passivation.

Purpose of the Study:

• To develop a novel hybrid ligand co-passivation strategy for PbSe QD solar cells.
• To address the challenges of etching and poor passivation in PbSe QDs.
• To improve the performance of IR solar cells.

Main Methods:

• A hybrid ligand co-passivation strategy using halide anions and Cd cations was employed.
• Passivation targeted both Pb and Se sites in PbSe QDs.
• The strategy aimed to improve QD solid quality, trap-state control, and carrier lifetime.

Main Results:

• The hybrid passivation strategy significantly improved PbSe QD solid quality.
• Excellent trap-state control and prolonged carrier lifetime were achieved.
• Record IR power conversion efficiency (IR-PCE) of 1.31% under 1100-nm-filtered solar illumination was obtained.
• High external quantum efficiency (EQE) of 80% at ~1295 nm was demonstrated.

Conclusions:

• The hybrid ligand co-passivation strategy is effective for enhancing PbSe QD solar cell performance.
• This approach overcomes previous limitations related to PbSe QD passivation.
• The achieved results represent a significant advancement in PbSe QD-based IR solar cell technology.