Near-Unity-Efficiency Charge Transfer and Quantum Confinement-Regulated Long-Lifetime Charge Recombination in 2D...

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Transition metal dichalcogenides (TMDs) show promise for optoelectronics but suffer from weak light absorption and short carrier lifetimes.
• Heterostructures (HSs) combining TMDs with 2D perovskites offer a strategy to enhance optoelectronic device performance.
• Understanding interfacial charge dynamics in TMD/2D perovskite HSs is crucial but remains underexplored.

Purpose of the Study:

• To investigate photogenerated carrier transfer and interlayer recombination in monolayer WS2/2D perovskite HSs with varying 2D perovskite structures (n=1, 2, 4).
• To elucidate the influence of quantum confinement on recombination dynamics within these HSs.

Main Methods:

• Fabrication of monolayer WS2/2D perovskite heterostructures with n=1, 2, and 4.
• Time-resolved spectroscopy techniques to probe ultrafast charge transfer dynamics.
• Selective optical excitation of WS2 or 2D perovskite layers to study carrier transfer pathways.

Main Results:

• Observed ultrafast hole transfer from monolayer WS2 to n=1 2D perovskite within 200 fs.
• Demonstrated ultrafast electron transfer from n=4 2D perovskite to monolayer WS2 within 2.5 ps.
• Found that increasing the n-value (reducing quantum confinement) significantly extends the interlayer electron-hole recombination lifetime from 0.2 ns (n=1) to 8.6 ns (n=4).

Conclusions:

• Monolayer WS2/2D perovskite heterostructures exhibit tunable ultrafast charge transfer (hole transfer from WS2 to perovskite, electron transfer from perovskite to WS2).
• Quantum confinement effects in 2D perovskites critically influence interlayer electron-hole recombination lifetimes.
• These findings provide essential insights for designing high-performance optoelectronic devices based on TMD/2D perovskite heterostructures.