Harnessing Atomic-Scale Thinning in Two-Dimensional Organic Molecular Crystals for In-Situ Characterization and...

Area of Science:

• Materials Science
• Condensed Matter Physics
• Organic Electronics

Background:

• Two-dimensional organic single crystals (2D OSCs) possess unique quantum properties for advanced optoelectronics.
• Probing the structure-optoelectronic relationship in 2D OSCs is crucial but challenging.

Purpose of the Study:

• To develop an in situ method for characterizing 2D OSCs.
• To investigate the effects of atomic thinning on exciton dynamics and electronic properties.
• To demonstrate the application of thinned 2D OSCs in neuromorphic computing.

Main Methods:

• Atomically precise thinning of 3D pentacene crystals to the monolayer limit.
• In situ optoelectronic characterization techniques.
• Fabrication and testing of 2D pentacene-based synapse devices.

Main Results:

• Thinning induced a phase transition from Frenkel to charge-transfer (CT) excitons with ~95.1% quantum yield.
• Improved carrier mobility and reduced threshold voltages were observed.
• A record paired-pulse facilitation index (~261%) was achieved in a synapse device.

Conclusions:

• Atomically precise thinning is an effective strategy to tune exciton properties and electronic performance in 2D OSCs.
• The developed 2D pentacene crystals enable high-performance neuromorphic devices.
• This work provides a foundation for multifunctional optoelectronic applications and understanding intrinsic 2D OSC properties.