Polyimide-Based Covalent Organic Framework as a Photocurrent Enhancer for Efficient Dye-Sensitized Solar Cells

Area of Science:

• Materials Science
• Nanotechnology
• Renewable Energy

Background:

• Covalent organic frameworks (COFs) offer high porosity, thermal stability, and ordered conjugated structures beneficial for optoelectronic applications.
• Dye-sensitized solar cells (DSSCs) are a key area for renewable energy research, with ongoing efforts to improve their power conversion efficiency (PCE).

Purpose of the Study:

• To synthesize polyimide COFs (PI-COFs) and investigate their functionality when doped into the TiO2 photoelectrode of a DSSC.
• To explore the role of PI-COFs in enhancing charge migration, separation, and light harvesting in conjunction with N719 dye.

Main Methods:

• Synthesis of PI-COFs via condensation of pyromellitic dianhydride (PMDA) and tris(4-aminophenyl) amine (TAPA).
• Doping of PI-COFs into TiO2 photoelectrodes of DSSCs.
• Surface modification of PI-COF particles using oxygen plasma treatment.

Main Results:

• Doping with 0.04 wt % PI-COFs enhanced DSSC power conversion efficiency from 9.05% to 9.93% by increasing short-circuit current density (Jsc) from 17.43 to 19.03 mA/cm².
• PI-COFs improved Jsc by enhancing charge transfer/injection and suppressing charge recombination through host-guest interactions.
• Oxygen plasma treatment resulted in a champion cell with a PCE of 10.46% and Jsc of 19.43 mA/cm², attributed to improved hydrophilicity and TiO2 linkage.

Conclusions:

• PI-COFs act as bifunctional materials, improving charge dynamics and light harvesting in DSSCs.
• The PI-COF/TiO2 composite photoelectrode, especially after oxygen plasma modification, shows significant potential for advancing DSSC technology.
• This doping strategy offers a promising pathway for developing highly efficient and stable solar cells.