Designing Semiconductor Nanowires for Efficient Photon Upconversion via Heterostructure Engineering

Area of Science:

• Nanophotonics and Nano-optoelectronics
• Semiconductor Nanowire Heterostructures
• Optical Energy Conversion

Background:

• Achieving high energy upconversion efficiency in semiconductor nanowires (NWs) is critical for advanced nano-optoelectronic and nanophotonic devices.
• Efficient upconversion under low excitation power remains a significant challenge, limiting device dynamic range.

Purpose of the Study:

• To drastically enhance energy upconversion efficiency in NW heterostructures.
• To demonstrate efficient two-step two-photon absorption (TPA) via engineered band states.
• To provide design guidelines for high-efficiency photon upconversion.

Main Methods:

• Fabrication of radial GaAs(P)/GaNAs(P) core/shell NW heterostructures.
• Design of heterostructures to facilitate a real intermediate TPA step with long carrier lifetime.
• Engineering electric-field distribution for maximized light absorption within the NWs.

Main Results:

• Achieved a 500-fold increase in upconversion efficiency compared to constituent materials.
• Demonstrated high efficiency under low excitation power (100 mW/cm², comparable to 1 sun illumination).
• Further improved efficiency by 8 times through electric-field engineering.

Conclusions:

• Core/shell NW heterostructures are highly effective for efficient photon upconversion.
• The demonstrated upconversion efficiency is among the highest reported for semiconductor nanostructures.
• The study provides valuable design principles for future high-performance upconversion devices.