Source Material Design for Realizing >50% Indium-Saving Transparent Electrode toward Sustainable Development of...

Area of Science:

• Materials Science
• Solid State Physics
• Semiconductor Research

Background:

• Indium (In) reduction is critical for transparent conductive oxide (TCO) development, with current strategies focusing on thin films or indium-free alternatives, yet lacking industrial solutions.
• Indium zinc oxide (IZO) is explored as a potential TCO, but high ZnO content can limit carrier mobility in indium oxide (In2O3) based films.

Purpose of the Study:

• To develop an indium-reduced TCO solution by reducing indium content in the source material using reactive plasma deposition (RPD).
• To investigate the properties and stability of indium zinc oxide (IZO) films for solar cell applications.
• To evaluate the performance of IZO films in silicon heterojunction (SHJ) solar cells.

Main Methods:

• Designed an indium zinc oxide (IZO) target with a Zn3In2O6 composition for reactive plasma deposition (RPD).
• Utilized density functional theory (DFT) to understand the electronic structure implications of ZnO introduction.
• Optimized the RPD process to achieve desired film properties and conducted material characterization (XPS, optical band gap) and stability tests (damp heat).

Main Results:

• Achieved a minimal resistivity of 6.08 × 10^-4 Ω·cm, with electron mobility of 31 cm^2 V^-1 s^-1 and carrier concentration of 3.37 × 10^20 cm^-3.
• The resulting amorphous IZO film exhibited an optical band gap of ~3.6 eV and demonstrated strong stability under damp heat tests with no aging effects.
• Demonstrated wafer-scale silicon heterojunction (SHJ) solar cells using IZO films, showing higher fill factor parameters compared to reference hydrogenated cerium-doped indium oxide (ICO) cells.

Conclusions:

• The developed indium-reduced IZO film via RPD presents a viable alternative to traditional TCOs, offering comparable electrical properties and enhanced stability.
• This amorphous IZO film is suitable for temperature-sensitive applications, including silicon heterojunction (SHJ) and perovskite/silicon tandem solar cells, and flexible OLEDs.
• The study highlights the potential of RPD and tailored target composition for advancing sustainable TCO development.