Interface engineering by piezoelectric potential in ZnO-based photoelectrochemical anode

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Photoelectrochemical (PEC) water splitting is a promising technology for renewable energy.
• Controlling semiconductor interfaces is crucial for optimizing PEC performance.
• The piezotronic effect, utilizing piezoelectric polarization, offers a novel approach to interface engineering.

Purpose of the Study:

• To demonstrate the engineering of heterogeneous semiconductor interface barrier heights via the piezotronic effect.
• To investigate the impact of piezoelectric polarization on photocurrent in PEC water splitting.
• To quantify the relationship between applied strain and barrier height changes at the ZnO/ITO interface.

Main Methods:

• Fabrication of a ZnO anode for photoelectrochemical water splitting.
• Application of tensile and compressive mechanical strains to the ZnO anode.
• Measurement of photocurrent variations and analysis of barrier height changes at the ZnO/ITO interface.
• Investigation of remnant piezopotential and its dependence on material screening lengths.

Main Results:

• Consistent enhancement or reduction of photocurrent was observed with tensile or compressive strain, respectively.
• A barrier height change of approximately 1.5 mV per 0.1% applied strain was quantified.
• A 0.21% tensile strain resulted in a ~10% improvement in maximum PEC efficiency.
• The remnant piezopotential was found to be dictated by the screening length of adjacent materials.

Conclusions:

• The piezotronic effect provides an effective strategy for tuning semiconductor interface properties for enhanced PEC water splitting.
• Remnant piezopotential plays a significant role in modulating photocurrent by altering interface barrier heights.
• Understanding the interplay between piezoelectricity, strain, and interface charge distribution is key to optimizing PEC devices.