With their high efficiency and cheap production costs, perovskite solar cells (PSCs) are seen as a strong contender for next-generation photovoltaic technology that might completely change the renewable energy sector. The layer-by-layer manufacturing method that is now in use, however, has problems that have prevented the commercialization of this technology.
The National Renewable Energy Laboratory (NREL) in the United States and City University of Hong Kong (CityU) academics have collaborated to create an original one-step solution-coating technology that streamlines the manufacturing process and decreases the commercialization obstacles for PSCs. The study’s results were released in the peer-reviewed scientific journal Nature Energy under the heading “Co-deposition of hole-selective contact and absorber for improving the processability of perovskite solar cells.”
“Reducing the number of device-processing steps without sacrificing device efficiency will help reduce process complexity and manufacturing cost, which will enhance the manufacturability of PSCs,” said Dr. Zhu Zonglong, a co-leader of the research and an assistant professor in CityU’s Department of Chemistry.
“We addressed the manufacturing issue by developing a novel method for co-processing the hole-selective contact and perovskite layer in a single step, yielding state-of-the-art efficiency of 24.5% and exceptional stability for inverted perovskite solar cells.” “This brings the technology’s commercialization one step closer,” he added.
PSCs are typically made utilizing a layer-by-layer method that includes successively depositing distinct solar cell layers on top of one another. Although this method has been effective in creating high-performance perovskite solar cells, it has drawbacks that might prevent its commercialization, including higher production costs, uneven uniformity, and poor repeatability.
Dr. Joseph M. Luther from NREL and Dr. Zhu worked together to develop a new method for creating effective inverted perovskite solar cells that allow the hole-selective contact and perovskite light absorber to spontaneously form in a single solution-coating procedure.
They discovered that adding particular phosphonic or carboxylic acids to perovskite precursor solutions causes the solution to self-assemble on the indium tin oxide substrate during perovskite film manufacturing. While the perovskite crystallizes, they create a strong self-assembled monolayer that serves as a good hole-selective contact. This single solution-coating strategy not only eliminates wettability difficulties but also simplifies device manufacturing by producing both the hole-selective contact and the perovskite light absorber at the same time, as opposed to the traditional layer-by-layer method.
The newly developed PSC device has a power conversion efficiency of 24.5% and can keep more than 90% of its initial efficiency after 1,200 hours of continuous operation at the maximum power point. Its efficiency is comparable to other PSCs on the market.
The multidisciplinary team also demonstrated that the novel strategy works with different self-assembled monolayer molecular systems, perovskite compositions, solvents, and scalable processing processes, such as spin-coating and blade-coating procedures. Additionally, the PSCs created using the new method operate similarly to those created using earlier techniques.
Dr. Zhu stated, “By introducing this novel strategy, we hope to contribute to the perovskite research community by proposing a more user-friendly method for producing high-performance perovskite solar cells and potentially accelerating the process of bringing them to market.”
In order to find the best set of self-assembled monolayer molecules for this method and improve the PSCs’ overall performance, the study team intends to further investigate the connection between self-assembled monolayer molecule architectures and perovskite precursors.