Inexpensive non-toxic perovskite-based semiconductor material developed

“Overall, the study has enabled a giant leap in the development of a cheaper, non-toxic, narrow optical band gap, tin-containing semiconductor material for practical applications in solar cells, photocatalysis and pigments”Katsuro Hayashi

Scientists at the Tokyo Institute of Technology, Kyushu University and Nagoya University in Japan have demonstrated the synthesis of a perovskite semiconductor material that can absorb a wide range of visible light with potential photofunctional applications. Their findings could offer an innovative and efficient approach to reducing the band gap in cheaper and non-toxic tin-based oxide semiconductors, which would help promote the production of lead-free visible-light absorbing materials for a range of light-based applications.

With narrow-gap semiconductors that use visible light becoming of increasing interest to researchers, mainly due to their versatility, here a team of material scientists led by Kazuhiko Maeda, whose work was reported in the journal Chemistry of Materials [Nakamura et al. Chem. Mater. (2021) DOI: 10.1021/acs.chemmater.1c00460], developed and characterized a new semiconductor material that can be applied in process components stimulated by light.

Semiconductors that can exploit the visible spectrum of light for a range of technological applications could be a major breakthrough in materials research, especially as such semiconductors are usually very expensive and often toxic in nature. Here, the team produced a cheaper and non-toxic narrow band gap semiconductor material that offers potential “light-based”, or photofunctional, applications.

While oxide semiconductors that contain tin are more inexpensive than most other semiconductor materials, their photofunctionality is limited by a wide optical band gap. This new perovskite-based semiconductor material contains no toxic lead and is able to absorb a wide range of visible light. To achieve this, hydride ions were doped into the tin-containing semiconductor material, which helped to reduce the band gap from 4 eV to 2 eV due to the chemical reduction of the tin component.

They were able to identify a key tin reduction reaction in the semiconductor material from physicochemical measurements, which has the consequence of generating a “tin lone electron pair”, whose different electronic states contribute to the visible light absorption of the material. This desired property was achieved because of the prior introduction of oxygen defects into the material.

To assess that the semiconductor material was photofunctional, the team examined its applicability using a photoelectrode. This led them to observe that the material offered a clear anodic photoresponse up to the expected 600 nm. As corresponding author Katsuro Hayashi said, “Overall, the study has enabled a giant leap in the development of a cheaper, non-toxic, narrow optical band gap, tin-containing semiconductor material for practical applications in solar cells, photocatalysis and pigments”.