Wavy Graphene Nanoribbons Containing Periodic Eight-Membered Rings for Light-Emitting Electrochemical Cells.

Area of Science:

• Materials Science
• Organic Chemistry
• Nanotechnology

Background:

• Graphene nanoribbons (GNRs) possess tunable properties based on their geometry, crucial for optoelectronics and spintronics.
• Engineering GNR properties often focuses on edge structure and width, leaving non-hexagonal ring structures underexplored.
• Synthetic challenges have limited the exploration of GNRs with non-hexagonal ring inclusions.

Purpose of the Study:

• To synthesize and characterize novel wavy graphene nanoribbons (wGNRs) incorporating periodic eight-membered rings.
• To investigate the impact of non-planar geometry on the optoelectronic properties of GNRs.
• To demonstrate the potential of wGNRs in optoelectronic devices, specifically organic light-emitting electrochemical cells (OLECs).

Main Methods:

• A2B2-type Diels-Alder polymerization of dibenzocyclooctadiyne and a dicyclopenta[e,l]pyrene-5,11-dione derivative.
• Selective Scholl reaction on the resulting ladder-type polymer precursor.
• Characterization using solid-state NMR, FT-IR, Raman, UV/Vis spectroscopy, and DFT calculations.

Main Results:

• Successful synthesis of wavy graphene nanoribbons (wGNRs) up to 30 nm in length.
• The non-planar geometry of wGNRs effectively suppresses inter-ribbon π-π aggregation.
• Demonstrated photoluminescence in solution, a key property for emissive applications.
• wGNRs were successfully employed as emissive layers in organic light-emitting electrochemical cells (OLECs).

Conclusions:

• The developed synthetic route enables the creation of GNRs with non-hexagonal ring structures.
• The unique structure of wGNRs leads to desirable photoluminescent properties.
• wGNRs show promise for advancing organic light-emitting electrochemical cell technology and other optoelectronic applications.