A perovskite solar cell fabricated using the new one-step solution spin-coating method. Photo: Zhu Zonglong’s research group/City University of Hong Kong.
A perovskite solar cell fabricated using the new one-step solution spin-coating method. Photo: Zhu Zonglong’s research group/City University of Hong Kong.

Perovskite solar cells (PSCs) are considered a promising candidate for next-generation photovoltaic technologies with high efficiency and low production costs, potentially revolutionizing the renewable energy industry. However, the existing layer-by-layer manufacturing process for PSCs presents challenges that have hindered the commercialization of this technology.

Now, researchers from City University of Hong Kong (CityU) and the National Renewable Energy Laboratory (NREL) in the US have jointly developed an innovative one-step solution-coating approach that simplifies the manufacturing process and lowers the commercialization barriers for PSCs. They report this work in a paper in Nature Energy.

“Reducing the number of device-processing steps without sacrificing device efficiency will help reduce the process complexity and manufacturing cost, which will enhance the manufacturability of PSCs,” explained Zhu Zonglong, an assistant professor in the Department of Chemistry at CityU and a co-leader of the research.

“We addressed the manufacturing issue with a novel approach to co-process the hole-selective contact and perovskite layer in a single step, resulting in state-of-the-art efficiency of 24.5% and exceptional stability for inverted perovskite solar cells. This helps bring the commercialization of the technology one step closer.”

Typically, PSCs are fabricated using a layer-by-layer process that involves sequentially depositing different layers of the solar cell on top of each other. While this approach has been successful in producing high-performance PSCs, it can cause issues that may hinder their commercialization, such as increased fabrication costs and unsatisfactory uniformity and reproducibility.

To improve the manufacturability of PSCs, Zhu collaborated with Joseph Luther from NREL to jointly develop a new approach for fabricating efficient inverted PSCs in which the hole-selective contact and perovskite light absorber can spontaneously form in a single solution-coating procedure.

The researchers found that if they added specific phosphonic or carboxylic acids to perovskite precursor solutions, the solutions will self-assemble on an indium tin oxide substrate during perovskite film processing. The acids form a robust self-assembled monolayer that functions as an excellent hole-selective contact while the perovskite crystallizes. This single solution-coating procedure not only solves wettability issues, but also simplifies device fabrication by creating both the hole-selective contact and the perovskite light absorber simultaneously, instead of the traditional layer-by-layer process.

The newly created PSC device has a power conversion efficiency of 24.5% and can retain more than 90% of its initial efficiency even after 1200 hours of operating at the maximum power point under continuous illumination. Its efficiency is comparable to that of similar PSCs on the market.

The collaborative team also showed that this new approach is compatible with various self-assembled monolayer molecular systems, perovskite compositions, solvents and scalable processing methods such as spin-coating and blade-coating techniques. And the PSCs fabricated with the new approach have comparable performance with those produced by other methods.

“By introducing this innovative approach, we hope to contribute to the perovskite research community by proposing a more straightforward method for manufacturing high-performance perovskite solar cells and potentially accelerating the process of bring them to market,” said Zhu.

The research team plans to further explore the relationship between self-assembled monolayer molecule structures and perovskite precursors to identify an optimal group of self-assembled monolayer molecules for this technique, thereby enhancing the overall performance of PSCs.

This story is adapted from material from City University of Hong Kong, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.