Photoactive Thiophene-Enriched Tetrathienonaphthalene-Based Covalent Organic Frameworks

Area of Science:

• Materials Science
• Organic Chemistry
• Nanotechnology

Background:

• Covalent Organic Frameworks (COFs) offer tunable optoelectronic properties through molecular design.
• Thiophene-based materials are crucial for enhancing charge transport in organic electronics.

Purpose of the Study:

• To synthesize novel thiophene-enriched COFs using a tetrathienonaphthalene (TTNTA) building block.
• To investigate the optoelectronic properties and photoactivity of these new COFs for potential applications.

Main Methods:

• Facile synthesis of TTNTA node and subsequent construction of imine-linked COFs (TT COF and BDT(BT)2 COF) using aldehyde-functionalized linkers.
• Solvothermal method for preparing highly crystalline and oriented COF films.
• Optical-pump terahertz-probe spectroscopy for charge-carrier mobility measurements.
• Photoelectrochemical water splitting experiments to assess photoactivity.

Main Results:

• High crystallinity and orientation achieved for TTNTA-based COF films.
• Effective charge-carrier mobilities of 0.34 ± 0.04 cm²V⁻¹s⁻¹ (TT COF) and 0.18 ± 0.02 cm²V⁻¹s⁻¹ (BDT(BT)2 COF) were measured.
• Demonstrated photoactivity as photocathodes in water splitting, yielding photocurrent densities of 10 and 15.3 µA cm⁻².

Conclusions:

• TTNTA-based COFs possess significant potential for optoelectronic applications.
• The design of thiophene-enriched COFs with high crystallinity and photoactivity is feasible.
• These materials show promise for efficient solar energy conversion technologies.