Kinetic photovoltage along semiconductor-water interfaces

Area of Science:

• Materials Science
• Condensed Matter Physics
• Physical Chemistry

Background:

• External photo-stimuli on heterojunctions typically create potential gradients across interfaces, leading to devices like solar cells.
• In-plane potential gradients along interfaces are rarely observed, limiting potential applications.

Purpose of the Study:

• To investigate the induction of in-plane photoelectric voltage at silicon-water interfaces.
• To explore the underlying mechanism and potential applications of this phenomenon.

Main Methods:

• Scanning a light beam across silicon-water interfaces.
• Utilizing polar liquids and hydrogels on silicon surfaces.
• Constructing a portable silicon-hydrogel array for detection.

Main Results:

• A persistent in-plane photoelectric voltage was successfully induced along silicon-water interfaces by scanning light.
• The effect is attributed to charge packet movement driven by light-induced potential changes and water's high permittivity.
• In-plane photovoltage generation was observed with polar liquids and hydrogels, but not nonpolar liquids.

Conclusions:

• This study demonstrates a novel method for generating in-plane photovoltage at semiconductor-liquid interfaces.
• The findings open new avenues for silicon-based photoelectronics and sensing applications.
• A portable silicon-hydrogel array was developed for detecting shadow paths, showcasing practical utility.