Enhanced up-conversion for photovoltaics via concentrating integrated optics

Area of Science:

• Materials Science
• Renewable Energy
• Optics

Background:

• Up-conversion photovoltaic (UC-PV) devices aim to harness sub-band-gap photons.
• Integrating concentrating optics is crucial for enhancing UC-PV performance.
• Silicon solar cells and specialized up-conversion materials are key components.

Purpose of the Study:

• To integrate concentrating optics into UC-PV devices.
• To independently focus sub-band-gap photons onto the up-conversion layer.
• To evaluate the impact of different concentrator designs on UC-PV performance.

Main Methods:

• Utilized silicon solar cells optimized for up-conversion.
• Employed tapered and parabolic dielectric concentrators.
• Incorporated hexagonal sodium yttrium fluoride (β-NaYF₄) up-converter doped with 25% trivalent erbium (Er³⁺).

Main Results:

• Achieved normalized external quantum efficiencies of 1.75x10⁻² cm²/W (tapered) and 3.38x10⁻² cm²/W (parabolic).
• Demonstrated that low to moderate light concentration maximizes up-conversion (UC).
• Observed saturation and reduced efficiency at higher concentrations.

Conclusions:

• The study highlights implications for developing advanced UC-PV devices.
• Dielectric concentrators significantly improve UC-PV performance.
• This work represents a substantial step towards integrating UC-PV in concentrating photovoltaic systems.