Researchers develop new technique to upscale the production of perovskite solar cells

Perovskite solar cells have potential as a future energy technology because of their high performance and low production cost. However, researchers find it challenging to bring this promising photovoltaic technology into commercial use because of the difficulty in upscaling from small-size laboratory devices to large-scale modules or panels needed for commercial use. A research team has demonstrated that a self-assembled monolayer can facilitate the formation of a large-area perovskite film  using a blade-coating process, and thus promote the upscaling of perovskite photovoltaic technology. They believe their new process will enable the commercialization of the perovskite solar cell technology.

 

The team published their findings on May 12, 2022, in Nano Research Energy. (DOI 10.26599/NRE.2022.9120004)

 

Photovoltaic solar cells use semiconductors to convert the energy from light into electricity. Since the 1950s, silicon has been the primary semiconductor material used in solar cells. However, developing large silicon crystals that conventional solar panels require depends on expensive, time-consuming manufacturing processes. Scientists have turned to perovskites to make semiconductors with properties that are similar to silicon. Perovskites with their specific crystal structure, get their name from the mineral with that same structure. Compared to silicon, perovskites can be manufactured at a great savings of cost and energy. Additionally, perovskite solar cells are lightweight and versatile enough to be used in places like windows and contoured roofs. The world record efficiency of the perovskite solar cells is as high as 25.7 percent, which rivals the efficiency of the silicon solar cells.

 

Researchers build perovskite solar cells with layers of material deposited on an underlying layer called the substrate. In adapting the high-speed blade-coating method for perovskite thin-film deposition, the researchers realized that the surface properties of the substrate are critical for large-area coating and perovskite growth. The current process leaves voids at the buried interface of the perovskite film that is detrimental to the device performance. “To solve this problem, we have screened various hole-transporting materials and found that self-assembled monolayers are a class of promising materials for the upscaling of perovskite devices,” said Alex Jen, a professor at City University of Hong Kong.

 

Self-assembled monolayers are an ordered array of organic molecules. They contain an anchoring group that can bond to the substrate and a functional headgroup to passivate the defects for the perovskite on top. These self-assembled monolayer molecules function as linkers, to bond the substrate and perovskite films tightly to eliminate interfacial voids. “Furthermore, since the self-assembled monolayer is a monolayer, charge carriers can be extracted from perovskite to substrate electrode efficiently through charge tunneling, resulting in enhanced device performance,” said Jen.

 

These functional self-assembled monolayers, that can be solution-processed, are very economical because of the minimal materials required. The self-assembled monolayers prove to be very effective for tuning the perovskite growth and passivating any potential defects. “This novel class of materials is very promising for facilitating the upscaling of perovskite photovoltaic technology,” said Jen.

 

Looking ahead to future studies, the researchers plan to employ different self-assembled monolayer molecules designed for upscaling the perovskite photovoltaic technology. In addition to further exploration of the self-assembled monolayer molecule design and synthesis, the team also plans to conduct composition engineering of perovskite precursors for upscaling coating methods. The interaction between perovskite and self-assembled monolayers is critical.

In order to achieve highly efficient and stable photovoltaic modules, the coating of perovskites has to be uniform and free of defects. “We believe our research will help reduce the lab-to-fab gap to facilitate the commercialization of perovskite photovoltaic technology,” said Jen.

 

The research team includes Jie Zeng, Leyu Bi, Yuanhang Cheng, and Alex K.-Y. Jen from the City University of Hong Kong; and Baomin Xu from the Southern University of Science and Technology, Shenzhen, China.

 

This research is funded by the APRC Grant of the City University of Hong Kong and the GRF grant from the Research Grants Council of Hong Kong.

 

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About Nano Research Energy 

 

Nano Research Energy is launched by Tsinghua University Press, aiming at being an international, open-access and interdisciplinary journal. We will publish research on cutting-edge advanced nanomaterials and nanotechnology for energy. It is dedicated to exploring various aspects of energy-related research that utilizes nanomaterials and nanotechnology, including but not limited to energy generation, conversion, storage, conservation, clean energy, etc. Nano Research Energy will publish four types of manuscripts, that is, Communications, Research Articles, Reviews, and Perspectives in an open-access form.

 

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