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N-type Conductive Tin Sulfide Thin Films: Towards Environmentally Friendly Solar Cells

Tin sulfide (SnS) is an abundant, safe, and environmentally friendly solar cell material. This inexpensive material is forecast to be used in next-generation solar cell panels.

A research group led by Issei Suzuki and Sakiko Kawanishi, assistant professors at Tohoku University's Institute of Multidisciplinary Research for Advanced Materials, has fabricated n-type conductive SnS thin films by impurity doping for the first time.

Conventional SnS thin films are usually p-type conductive. Thus, SnS thin-film solar cells have been fabricated using a pn heterojunction with p-type SnS thin film and other n-type semiconductor thin films, such as CdS. However, the conversion efficiency of such heterojunction devices has stagnated at approximately 5%, rendering their use impractical.

The SnS thin-film solar cells employing a pn homojunction, which uses SnS thin films for both p-type and n-type layers, is expected to exhibit higher conversion efficiency. Yet, n-type conducive SnS thin films without toxic elements have never been achieved before.

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The world's first n-type conductive SnS thin film without containing toxic elements. ©Issei Suzuki et al.

Utilizing chlorine-doping and a sulfur plasma supply, the research group reduced the lattice defects inhibiting the n-type conversion of SnS, realizing the world's first n-type SnS thin films without toxic elements.

190_20211213_PR_ntype_conductive_sns_thin_type_films_pic2.png

A schematic illustration of the new technique used to fabricate n-type SnS thin films. The n-type conductive SnS thin films were achieved by fabricating thin films of chlorine(Cl)-doped SnS with a supply of sulfur plasma. ©Issei Suzuki et al.

"Our realization paves the way for practical pn homojunction SnS thin-film solar cells," said Suzuki.

The results of the research were published in Physical Review Materials on December 9, 2021.

Publication Details:

Title: N-Type Electrical Conduction in SnS Thin Films
Authors: Issei Suzuki, Sakiko Kawanishi, Sage R. Bauers, Andriy Zakutayev, Zexin Lin, Satoshi Tsukuda, Hiroyuki Shibata, Minseok Kim, Hiroshi Yanagi and Takahisa Omata
Journal: Physical Review Materials
DOI: https://doi.org/10.1103/PhysRevMaterials.5.125405

Press release in Japanese

Contact:

Issei Suzuki
Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University
Email: issei.suzukitohoku.ac.jp
Website: http://www2.tagen.tohoku.ac.jp/lab/omata/english/

Sakiko Kawanishi
Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University
Email: s-kawatohoku.ac.jp
Website: http://www2.tagen.tohoku.ac.jp/lab/shibata/english/

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