High-Mobility Semiconducting Two-Dimensional Conjugated Covalent Organic Frameworks with p-Type Doping

Area of Science:

• Materials Science
• Organic Electronics
• Nanotechnology

Background:

• Two-dimensional conjugated covalent organic frameworks (2D c-COFs) are promising semiconducting materials for optoelectronics and energy storage.
• Understanding doping mechanisms is crucial for tuning charge transport properties in 2D c-COFs, but remains largely unexplored.

Purpose of the Study:

• To investigate the effects of molecular iodine doping on a metal-phthalocyanine-based pyrazine-linked 2D c-COF.
• To elucidate the mechanism behind enhanced charge transport properties upon doping.

Main Methods:

• Synthesis of a metal-phthalocyanine-based pyrazine-linked 2D c-COF.
• Molecular iodine doping of the 2D c-COF.
• Electrical conductivity measurements.
• Hall effect measurements to determine carrier concentration and mobility.

Main Results:

• The iodine-doped 2D c-COF (ZnPc-pz-I) maintained structural integrity.
• Conductivity was enhanced by three orders of magnitude due to increased carrier concentration.
• Record carrier mobility of ~22 cm² V⁻¹ s⁻¹ was achieved, attributed to increased scattering time for charge carriers.

Conclusions:

• Molecular iodine doping is an effective strategy to significantly enhance conductivity and carrier mobility in 2D c-COFs.
• Doping mitigates scattering mechanisms, leading to improved charge transport.
• This work provides a framework for assessing doping effects in COFs and highlights their potential for advanced optoelectronic applications.