A new 3-D coordination polymer as a precursor for CuI-based thermoelectric composites

Area of Science:

• Materials Science
• Solid-State Chemistry
• Inorganic Chemistry

Background:

• Thermoelectric materials convert heat to electricity.
• Developing efficient thermoelectric composites is crucial for energy harvesting.
• Copper iodide complexes offer potential as precursors for these materials.

Purpose of the Study:

• To synthesize and characterize novel copper iodide complexes as precursors for thermoelectric composites.
• To investigate the structural properties of a new 3-D polymorph.
• To evaluate the thermoelectric performance of derived composites.

Main Methods:

• Synthesis of copper iodide complexes using a literature procedure.
• Characterization of a new polymorph using X-ray diffraction.
• Pyrolysis of complexes to form thermoelectric composites under nitrogen gas flow.
• Measurement of Seebeck coefficient and material properties.

Main Results:

• A new 3-D polymorph, [Cu4I4(L1)2]n (1), with a staircase structure was unexpectedly obtained.
• Composite 2, derived from polymorph 1, exhibited high carbon content (10.2 wt%) and a robust pellet form.
• Composite 2 showed a significant Seebeck coefficient ranging from 543 to 1308 μV K-1 between 70-240 °C.
• Composite 3, derived from a different complex, was fragile with low carbon content and poor thermoelectric properties.

Conclusions:

• The novel polymorph 1 is a promising precursor for high-performance thermoelectric composites.
• Composite 2 demonstrates excellent thermoelectric potential due to its structural integrity and electrical properties.
• The carbon content and structural stability of the derived composite are critical factors for thermoelectric performance.