Chemically Enhanced Raman Scattering Enabled by Organic Semiconductor Molecules with Deep Lowest Unoccupied Molecular...

Area of Science:

• Materials Science
• Spectroscopy
• Organic Electronics

Background:

• Surface-enhanced Raman scattering (SERS) is a powerful analytical technique.
• Organic semiconductor materials (OSMs) show promise as SERS substrates, but their potential is underexplored.
• Current SERS applications are limited to a few OSMs, like thiophene derivatives.

Purpose of the Study:

• To explore the broader library of OSMs for SERS applications.
• To investigate the role of energy level alignment, specifically the lowest unoccupied molecular orbital (LUMO) levels, in SERS activity.
• To develop novel SERS substrates for enhanced detection of organic molecules.

Main Methods:

• Utilizing OSMs with deep LUMO levels, such as TCNQ and HATCN.
• Employing low-energy incident laser irradiation at 785 nm.
• Analyzing the selective SERS enhancement for analytes with varying highest occupied molecular orbital (HOMO) levels.

Main Results:

• Demonstrated efficient SERS detection of multiple organic dyes previously undetectable.
• Showcased selective SERS enhancement influenced by analyte HOMO levels and substrate LUMO levels.
• Established a correlation between molecular structure, LUMO level tuning, and SERS activity.

Conclusions:

• OSMs with deep LUMO levels are effective SERS platforms.
• LUMO level engineering is crucial for optimizing SERS activity and molecular sensitivity.
• This strategy facilitates the rational design of new SERS substrates.