Flexo-photovoltaic effect in MoS₂.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Optoelectronics

Background:

• The Shockley-Queisser limit restricts conventional p-n junction solar cells.
• The bulk photovoltaic effect, observed in non-centrosymmetric materials, offers a route to overcome this limit.
• Flexo-photovoltaic effect, a strain-gradient-induced bulk photovoltaic effect, can be activated in centrosymmetric semiconductors.

Purpose of the Study:

• To experimentally demonstrate the flexo-photovoltaic effect in a centrosymmetric material.
• To explore strain-gradient engineering for activating the flexo-photovoltaic effect in two-dimensional (2D) materials.
• To investigate the potential of MoS₂ for enhanced photovoltaic applications.

Main Methods:

• Utilized strain-gradient engineering via a hybrid MoS₂/VO₂ system.
• Leveraged structural inhomogeneity and phase transition in the hybrid system to create strain gradients.
• Measured the bulk photovoltaic coefficient in MoS₂.

Main Results:

• Successfully demonstrated the flexo-photovoltaic effect in MoS₂.
• Achieved a bulk photovoltaic coefficient in MoS₂ that is orders of magnitude higher than in most non-centrosymmetric materials.
• Established a fundamental link between the flexo-photovoltaic effect and strain gradients in low-dimensional materials.

Conclusions:

• The flexo-photovoltaic effect can be effectively induced in centrosymmetric semiconductors like MoS₂ through strain-gradient engineering.
• MoS₂ exhibits exceptional performance for the flexo-photovoltaic effect, surpassing many non-centrosymmetric materials.
• This work opens avenues for novel optoelectronic devices and energy applications using strain-gradient-engineered low-dimensional materials.