A new collaborative study between UNIST and the Korea Research Institute of Chemical Technology (KRICT) has presented a new manufacturing method to produce inorganic-organic hybrid perovskite solar cells (PSCs). Apart from the method being cost-efficient, the solar cells have set a new world record for efficiency performance, specifically photo stability. The research team hope that this platform and method will contribute significantly to the acceleration of the commercialization of PCSs.

The research was done by Professor Sang-Il Seok of the Energy and Chemical Engineering department at UNIST, in partnership with Dr. Jun and Dr. Seong Sik Shin from KRICT. The results were published in the March issue of the prestigious online journal Science. The method has been hailed by researchers across the world as the most promising candidate for the next generation of high efficiency solar cell technology.

A mixture of inorganic elements and organic molecules within a solitary crystalline structure are used to make PSCs. Together, these capture light and transform it into electricity. A PSC is a unique crystal structures, consisting of one anion and two cations. They can be produced cheaper and easier than silicon based solar cells, and are fabricated on rigid or flexible substrates. PSCs have been attracting much attention as the next-generation solar cells, as they are able to reach a photovoltaic efficiency of 22.1 percent, which is comparable to that of single crystalline silicon solar cells at 25 percent.

Seok has led PSC technology as a top scientist in the field and this new development is based on his previous work on new architecture, process and composition for PSCs. In this paper, the research team described the fabrication of PSCs that satisfies both high photo stability and high efficiency (21.2%) of the perovskite solar cells. Using photo electrode materials (Lanthanum (La)-doped BaSnO3 (LBSO)) synthesized by an original method under mild conditions (below 200°C), they used methylammonium lead iodide (MAPbI3) peorvskite materials for PSCs.

Photo stability refers to the capability of a material to withstand exposure to light without a serious degradation. The new material presented by Seok’s research team, retains 93 percent of its initial performance after 1,000 hours of exposure to sunlight. Fabrication is also much easier, as the synthesis of the photo electrode material can be done at less than 200°C, which is much lower than that of conventional synthesis that is typically done at over 900°C.

A new solar cell manufacturing methodology dubbed the ‘Hot Pressing Method’ was also proposed in the study. This method tightly bonds two objects by applying pressure and temperature. It allows the production of stable and high efficiency perovskite solar cells at a low cost.

Seok, the corresponding author of the paper noted that the study combined the hot pressing method and the newly synthesized photo electrode material. This lowers the manufacturing cost to less than 50% of that of existing silicon solar cells. He added that the study helped the team produce PSCs with excellent photo stability and a steady state power conversion efficiency of 21.2%.

Seok concluded that this achievement was made possible by the unique technology of domestic researchers. In the process, they have surpassed the conventional stability and low efficiency limits of next generation solar cell technology.

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