Ultrafast directional hot carrier transfer in bilayer perovskite heterojunctions.

Ultrafast hot carrier transfer in bilayer CsPbBr3/FAPbBr3 perovskite heterojunctions enables laser thresholds five times lower than individual layers.

• Why it matters: Understanding and controlling hot carrier dynamics is crucial for surpassing the efficiency limits of optoelectronic devices, yet the mechanisms of ultrafast transfer remain underexplored.
• What they did: Using ultrafast spectroscopy, the study demonstrates hot carriers generated in FAPbBr3 are directed to CsPbBr3 within picoseconds, driven by differences in cooling pathways and density gradients.
• The result: This ultrafast transfer boosts carrier density to achieve population inversion, enabling hot-carrier lasers with significantly reduced thresholds, paving the way for advanced high-performance optoelectronic devices.