Dopant Control of Solution-Processed CuI:S for Highly Conductive p-Type Transparent Electrode

Area of Science:

• Materials Science
• Solid State Physics
• Nanotechnology

Background:

• Copper iodide (CuI) is a promising p-type transparent conducting oxide alternative due to its favorable electronic properties.
• Previous sulfur (S) doping via liquid iodination achieved a high figure of merit (FOM) of 63,000 MΩ⁻¹.
• Low-cost, large-area fabrication of solution-processed S-doped CuI (CuI:S) remains unexplored.

Purpose of the Study:

• To develop a low-temperature solution-processed CuI:S thin-film for p-type transparent conducting electrodes (TCEs).
• To optimize thiourea dopants for enhanced conductivity and carrier concentration.
• To investigate the potential for high-throughput fabrication methods.

Main Methods:

• Thin-film fabrication of CuI:S using low-temperature solution processing with various thiourea derivatives.
• Optimization of thiourea dopant through acid-base studies, considering steric hindrance effects.
• Characterization of carrier concentration, conductivity, and figure of merit (FOM).

Main Results:

• Achieved a wide range of carrier concentrations (9 × 10¹⁸–2.52 × 10²⁰ cm⁻³) and conductivities (4.4–390.7 S cm⁻¹).
• N-ethylthiourea-doped CuI:S demonstrated a record FOM of 7,600 MΩ⁻¹ for solution-processed p-type TCEs.
• The developed CuI:S solution is compatible with high-throughput techniques like inkjet printing and spray coating.

Conclusions:

• Low-temperature solution processing enables the fabrication of highly conductive CuI:S thin-films.
• Thiourea derivative optimization is crucial for tuning electrical properties and achieving high FOM.
• The developed CuI:S inks pave the way for cost-effective, large-area applications of p-type TCEs.