Sumitomo Heavy unveils reactive plasma tech for thin-film perovskite PV

Sumitomo Heavy Industries (SHI) has developed a new reactive plasma deposition (RPD) method to form ultra-thin tin oxide electron transport layers (ETL) for perovskite solar cells. It claims this enables low-temperature mass production with minimal substrate damage.

Sumitomo Heavy Industries has developed a new deposition technology for ultra-thin electron transport layers, a key component of next-generation perovskite solar cells. The Tokyo-based company said in a press release this week that the method uses cost-effective materials and a low-impact process, addressing major barriers to scaling perovskite technologies for mass production.

Perovskite solar cells include multiple functional layers, SHI said, explaining that one layer is an electron transport layer deposited either above or below the electricity-generating perovskite layer.

SHI noted that the electron transport layer plays a crucial role by allowing electrons generated in the perovskite layer to move efficiently to the electrode. To meet this function, the layer must have conduction bands capable of accepting these electrons. It is also important that the layer is deposited without harming the perovskite layer, which remains highly sensitive to elevated temperatures, explained the Tokyo-based industrial group.

“Although they are cost-effective and suitable for mass production, conventional formation methods typically involve high energy particles and high-temperature environments,” said SHI. “This, in turn, will make them incompatible with perovskite materials. Thus, manufacturers are actively exploring chemical film deposition methods.”

However, SHI acknowledged that this approach is still challenging due to high material costs, the difficulty in scaling up production, and the utilization of flammable or toxic precursor gases. It claimed that its RPD method, a type of physical vapor deposition (PVD), overcomes these challenges by enabling deposition of tin oxide (SnO2) films with insulating properties suitable for electron transport layers, achieving what it claims is a world-first for PVD-based ETLs.

RPD facilitates low-temperature, rapid, large-area deposition with minimal substrate damage, using non-hazardous gases and reducing environmental impact, said SHI. It claimed that the new technology also allows continuous integration of ETL deposition with transparent conductive film (TCF) deposition, such as indium tin oxide (ITO).

SHI stated that the new method also offers key improvements in mass production and cost efficiency compared with chemical deposition methods. It noted that SnO2 films can be deposited at more than 200 times the speed of current approaches, and ETL manufacturing costs are expected to fall to less than 0.5% of the conventional process, which typically involves depositing a fullerene (C60) layer followed by chemical vapor deposition of SnO2.

The company said it aims to accelerate perovskite solar cell adoption by applying this methodology to mass production, in line with the Japanese Ministry of Economy, Trade and Industry's (METI) plans to deploy 20 GW of perovskite solar capacity by 2040. METI has said that its 2040 perovskite target is part of broader plans to accelerate the adoption of next-generation solar technologies.

In January 2025, Sekisui Chemical launched pilot perovskite solar projects at two MUFG Bank sites in Japan to demonstrate the technology's durability and suitability for urban applications. A month later, a Japanese consortium of electronics supplier Macnica, thin-film PV manufacturer Reiko, and perovskite solar specialist Peccell Technologies began testing lightweight, flexible perovskite solar modules at a pier in Yokohama.

And in April, Japanese scientists achieved a record 26.5% efficiency in a flexible perovskite-silicon tandem solar cell, marking a significant advancement in high-performance, bendable photovoltaic technology.