Energy-conversion properties of vapor-liquid-solid-grown silicon wire-array photocathodes

Area of Science:

• Materials Science
• Photovoltaics
• Electrochemistry

Background:

• Silicon wire arrays are promising for photovoltaics and hydrogen generation but have shown poor performance.
• Previous research has not fully leveraged the potential of silicon microwire arrays for energy conversion.

Purpose of the Study:

• To develop an efficient method for growing ordered silicon wire arrays.
• To evaluate the performance of these silicon wire arrays as photocathodes for energy conversion.

Main Methods:

• Utilized a copper-catalyzed, vapor-liquid-solid-growth process with SiCl4 and BCl3.
• Grew ordered arrays of crystalline p-type silicon (p-Si) microwires on p+-Si(111) substrates.
• Tested the wire arrays as photocathodes in contact with an aqueous methyl viologen(2+/+) electrolyte.

Main Results:

• Achieved energy-conversion efficiencies of up to 3% with monochromatic 808-nanometer light.
• Observed internal quantum yields of at least 0.7, indicating efficient charge generation.
• Identified light absorption as the primary limitation, with arrays filling only 4% of the optical plane.

Conclusions:

• The developed silicon wire arrays demonstrate significant potential for efficient photovoltaic and photoelectrochemical energy conversion.
• The radial junction platform offers a promising design for future energy devices.
• Further optimization of light absorption can lead to even higher energy-conversion efficiencies.