Photo credit: www.sciencedaily.com

Advancements in Tin Sulfide Thin Films for Solar Energy Applications

Solar energy conversion is a pivotal aspect of the transition to cleaner energy sources. However, the incorporation of toxic materials in solar cells could undermine their environmental benefits. Enter tin sulfide (SnS), a sustainable and abundant semiconductor that presents a viable alternative for solar cells and thermoelectric devices.

Researchers from Tohoku University have conducted an in-depth study examining how variations in the 1:1 stoichiometric ratio of tin to sulfur affect the electrical properties and structure of SnS thin films. Achieving precise control over this ratio has historically been difficult, primarily due to sulfur’s high volatility during deposition processes.

To tackle this challenge, the team, spearheaded by Issei Suzuki, a senior assistant professor, and his PhD candidate Taichi Nogami, innovated a sulfur plasma-assisted sputtering technique that allows for meticulous control of sulfur levels in SnS thin films. This method diverges from conventional sputtering, which primarily involves atomizing a SnS sintered target and depositing the material onto a substrate. The introduction of plasma-activated sulfur has enabled the researchers to achieve targeted Sn:S ratios, including 1:0.81, 1:0.96, 1:1, and 1:1.04, allowing for detailed analysis of their structural and electrical properties.

“Our findings reveal that even minor adjustments in the composition of Sn and S can lead to significant changes in morphology,” states Suzuki. The study indicates that sulfur-rich compositions (S > 50%) result in a substantial increase in carrier density, whereas sulfur-deficient compositions (S < 50%) show minimal changes in carrier density. Furthermore, the research observed that non-stoichiometric films often resulted in rough and porous surfaces, while the stoichiometric SnS thin films (1:1) maintained a dense structure with enhanced hole mobility, positioning them as strong candidates for solar energy applications.

This research underscores the importance of accurately controlling sulfur content in SnS thin films, providing insights that could enhance their electrical and structural performance. This work builds upon previous studies by Suzuki and Nogami, which explored different variants of SnS thin films. The findings have the potential to advance the practical use of SnS in innovative energy conversion technologies.

“Looking ahead, our goal is to incorporate these optimized SnS thin films into high-efficiency solar cells,” Nogami elaborates. “We aim to refine their performance and scalability, paving the way for broader use in clean energy generation and contributing to efforts against climate change.”

Source
www.sciencedaily.com