Optimization of a Solution-Processed TiO/(n)c-Si Electron-Selective Interface by Pre- and Postdeposition Treatments

Area of Science:

• Materials Science
• Photovoltaics
• Semiconductor Devices

Background:

• Silicon heterojunction (SHJ) solar cells require high-performance carrier-selective materials.
• Current fabrication methods for these materials can be costly and energy-intensive.
• Developing vacuum-free, low-temperature deposition techniques is essential for reducing manufacturing costs and environmental impact.

Purpose of the Study:

• To investigate the effects of pre- and postdeposition treatments on solution-processed titanium dioxide (TiO2) for solar cell applications.
• To optimize TiO2 as an electron-selective passivation contact without compromising performance.
• To reduce the fabrication cost and CO2 footprint of SHJ solar cells.

Main Methods:

• Spin-coating of TiO2 on n-type silicon substrates.
• Tailoring pre- and postdeposition treatments for TiO2 layers.
• Investigating the impact of a LiF buffer layer between TiO2 and Al metal contact.
• Utilizing chemical and electrical characterizations to analyze passivation quality and contact resistivity.

Main Results:

• Achieved a low surface recombination velocity (SRV) of 6.54 cm/s and a high implied open-circuit voltage (iVoc) of 706 mV.
• Demonstrated remarkably improved electrical properties of the TiO2 layer through optimized treatments.
• Extracted a low contact resistivity (ρc) of 15.4 mΩ·cm² at the n-Si/SiO2/TiO2 heterojunction with a LiF buffer layer.
• Brought the performance of solution-processed TiO2 to a level comparable to state-of-the-art deposited TiO2 layers.

Conclusions:

• Tailor-made pre- and postdeposition treatments significantly enhance the passivation quality and contact resistivity of solution-processed TiO2.
• The optimized TiO2, with a LiF buffer, offers a viable pathway for cost-effective and high-performance SHJ solar cells.
• Improved electrical properties are attributed to the combined effects of chemical and field-effect passivation in the Si/SiO2/TiO2 heterojunction.