Reviewed by Alex SmithDec 5 2022
Solar cells will be crucial in the global switch to renewable energy as the movement toward carbon neutrality gains momentum and as a concerning pattern of rising temperatures and natural disasters brought on by global warming persists.
(a) A schematic of the interface between the SnS single crystal/MoO3 thin film analyzed in this study. (b) A sample actually used for the photoelectron spectroscopy measurement. Several single crystals are fixed on a stainless-steel plate. (c) A schematic energy band diagram of the present interface where SnS band exhibited large bending. Image Credit: Issei Suzuki et al.
A research team has now paved the way for tin sulfide (SnS) solar cells to achieve higher open-circuit voltage and thus realize their latent potential as a thin-film solar material.
Compound semiconductors with a high light absorption capacity are used in thin-film solar cells, which have a lower raw material requirement and are, therefore, lighter and less expensive to manufacture.
SnS is one such environmentally friendly thin-film solar cell material since it does not contain any rare or toxic elements. But in recent years, scientists have started to doubt this assumption because, despite more than 20 years of study, their conversion efficiency had only reached 5% due to a low open-circuit voltage.
The team from Tohoku University’s Institute of Multidisciplinary Research for Advanced Materials, led by Assistant Professor Issei Suzuki, successfully demonstrated an SnS interface exhibiting large band bending, which is required to achieve a higher open-circuit voltage.
We used photoelectron spectroscopy to analyze the electronic structure of the interface where molybdenum oxide was deposited on a SnS single crystal. We confirmed that the interface state achieved a high open-circuit voltage.
Issei Suzuki, Assistant Professor, Institute of Multidisciplinary Research for Advanced Materials, Tohoku University
Suzuki has made other advances in SnS thin-film solar cells in addition to this one. He oversaw another team that created the first n-type SnS thin film in the history of the world back in December 2021. This made it possible for homojunction to form in thin films.
In the current study, the team also put forth a technique for creating interfaces that are appropriate for SnS thin-film solar cells, which included lowering the sulfur deficiency in the SnS thin films and using a homojunction structure in both their n-type and p-type layers.
Suzuki added, “In the near future, we hope to fabricate homojunction solar cells with high conversion efficiency.”
Journal Reference:
Suzuki, I., et al. (2022) Avoiding Fermi Level Pinning at the SnS Interface for High Open-Circuit Voltage. The Journal of Physical Chemistry C. doi:10.1021/acs.jpcc.2c04212.