Broadband down-conversion for silicon solar cell by ZnSe/phosphor heterostructure

Area of Science:

• Materials Science
• Photovoltaics
• Luminescence

Background:

• Silicon solar cells are limited by their spectral response, necessitating methods to improve efficiency.
• Down-conversion enhances solar cell efficiency by converting high-energy photons into lower-energy photons within the cell's optimal absorption range.
• Trivalent lanthanide ion-based down-converters offer potential but suffer from narrow excitation bands.

Purpose of the Study:

• To design and fabricate a novel heterostructural down-converter with an expanded excitation band.
• To improve the energy transfer efficiency from a wide-bandgap semiconductor to a quantum cutting phosphor.
• To optimize down-conversion for enhanced silicon solar cell performance.

Main Methods:

• Fabrication of a heterostructure combining Y₂O₃: [(Tb³⁺-Yb³⁺), Li⁺] quantum cutting phosphor with ZnSe.
• Utilizing ZnSe as an energy absorption layer to capture short-wavelength incident light.
• Investigating energy transfer mechanisms from ZnSe to the Tb³⁺-Yb³⁺ couple.

Main Results:

• The heterostructural down-converter exhibits an excitation band spanning 250-550 nm.
• Efficient energy transfer from ZnSe to Tb³⁺-Yb³⁺ was achieved, converting short-wavelength light to Yb³⁺ emission at ~1000 nm.
• The emission wavelength aligns with the maximal spectral response of silicon solar cells.

Conclusions:

• The developed heterostructural down-converter effectively broadens the excitation band for improved solar energy harvesting.
• The energy matching between ZnSe and Tb³⁺ absorption maximizes down-conversion bandwidth.
• This approach offers a promising strategy for enhancing silicon solar cell conversion efficiency.