Plasmon‐Exciton Interaction Induced Efficient Charge Separation in Cu2‐xS‐CsPbBr3 Heterostructure

Why It Matters

The ability to harvest NIR photons and achieve rapid, directional charge separation can dramatically raise the efficiency of solar cells and photodetectors. This work demonstrates a scalable material strategy for next‑generation optoelectronics.

Key Takeaways

• Cu2‑xS plasmonic semiconductor couples with CsPbBr3 perovskite
• Hot‑hole transfer occurs under both 400 nm and 800 nm excitation
• 400 nm triggers hot‑electron transfer from perovskite to Cu2‑xS
• Charge separation delays exciton recombination, boosting device efficiency
• Heterostructure suitable for NIR‑responsive optoelectronic applications

Pulse Analysis

Plasmonic semiconductors such as Cu2‑xS have attracted attention for their tunable band gaps and strong near‑infrared absorption, offering a low‑cost alternative to noble‑metal plasmonics. When paired with lead‑halide perovskites like CsPbBr3, the resulting heterostructure creates a resonant plasmon‑exciton interaction that expands the optical cross‑section and opens new pathways for carrier dynamics. This synergy is especially valuable for devices that must operate beyond the visible spectrum, including solar concentrators and infrared photodetectors.

Transient absorption spectroscopy reveals that illumination at 800 nm excites the Cu2‑xS plasmon, generating hot holes that swiftly inject into the CsPbBr3 valence band. At 400 nm, the perovskite absorbs directly, producing hot electrons that flow back into the Cu2‑xS conduction band while the plasmon still drives hot‑hole transfer. The concurrent bidirectional flow creates a spatial charge gradient that prolongs exciton lifetimes and reduces recombination losses. Such efficient hot‑carrier extraction is a critical step toward surpassing the Shockley‑Queisser limit in photovoltaic architectures.

The demonstrated charge‑separation mechanism positions the Cu2‑xS‑CsPbBr3 system as a versatile building block for next‑generation optoelectronics. By capitalizing on inexpensive, solution‑processed materials, manufacturers can integrate NIR‑responsive layers into existing silicon or perovskite solar cells, boosting overall power conversion efficiency. Moreover, the rapid carrier dynamics are attractive for high‑speed photonic switches and infrared imaging sensors. Ongoing research will likely focus on scaling the heterostructure, optimizing interface chemistry, and embedding the material into device prototypes, paving the way for commercial adoption in energy and communication markets.