Ultrafast Charge Transfer and Delayed Recombination in Graphitic-CN/WTe₂ van der Waals Heterostructure: A Time Domain...

Area of Science:

• Materials Science
• Condensed Matter Physics
• Computational Chemistry

Background:

• Efficient solar energy harvesting is crucial for renewable energy technologies.
• Van der Waals heterostructures offer tunable electronic properties for optoelectronic applications.
• Understanding charge carrier dynamics is key to optimizing photovoltaic device performance.

Purpose of the Study:

• To investigate the atomistic charge carrier dynamics in graphitic carbon nitride (g-CN)-tungsten telluride (WTe2) van der Waals heterostructures.
• To elucidate the mechanisms behind ultrafast charge transfer and delayed electron-hole recombination.
• To provide insights for designing efficient next-generation photovoltaic devices.

Main Methods:

• Time-domain density functional theory (TD-DFT) calculations.
• Nonadiabatic molecular dynamics (NAMD) simulations.
• Analysis of electron-phonon coupling and nonadiabatic coupling (NAC).

Main Results:

• Predicted ultrafast electron transfer (589 fs) and hole transfer (807 fs) in g-CN/WTe2 heterostructures.
• Observed significantly delayed electron-hole recombination (2.404 ns) compared to individual g-CN (3 ps) and WTe2 (0.55 ps) monolayers.
• Attributed ultrafast charge transfer to strong electron-phonon coupling and delayed recombination to weaker electron-phonon coupling, sufficient band gap, lower NAC, and fast decoherence.

Conclusions:

• The g-CN/WTe2 heterostructure demonstrates superior charge carrier dynamics for solar energy applications.
• The interplay of electron-phonon coupling and nonadiabatic effects governs exciton relaxation in these 2D materials.
• These findings are valuable for the rational design of high-performance organic-inorganic 2D van der Waals heterostructure-based photovoltaic devices.