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Perovskite Solar Cells Set a New Record Efficiency of 22%

August 1, 2017 | Leave a Comment

Scientists in South Korea have developed a new cost-efficient way to produce inorganic -organic hybrid perovskite solar cells (PSCs) setting a new world-record efficiency performance of 22.1 percent in small cells and 19.7 percent in 1-square-centimeter cells.

Solar Cell State of Art July 2017. Image Credit: National Renewable Energy Lab. Click image for the largest view.

This breakthrough comes from a research conducted by Distinguished Professor Sang-Il Seok of Energy and Chemical Engineering at UNIST in collaboration with co-authors of the study Professor Jun Hong Noh of Korea Research Institute of Chemical Technology and Professor Eun Kyu Kim of Hanyang University whose study paper has been published in the journal Science.

A key feature of the new technology is its ability to fix the dominating defect in perovskite-halides, which is known to decrease the photoelectric efficiency. The team’s results, published online in the journal Science, demonstrates that careful control of the growth conditions of perovskite layers with management of deficient halide anions is essential for realizing high-efficiency thin-film PSCs based on lead-halide-perovskite absorbers.

Professor Seok said, “This study can improve the current record efficiency of perovskite solar cells from 20.1% to 22.1%. This will accelerate the commercialization of the low-cost, high-performance perovskite solar cells.”

A perovskite is an unique crystal structure, consisting of formamidinium with multiple cations and mixed halide anions. A perovskite solar cell is a type of solar cell, which includes the perovskite structured compound, most commonly a hybrid organic-inorganic lead or tin halide-based material, as the light-harvesting active layer.

Perovskite Hybrid Solar Cell at UNIST. Image Credit: UNIST. Click image for the largest view.

An organic-inorganic hybrid PSC is a type of solar cell which includes the perovskite structured compound as the light-harvesting active layer. Such devices have inspired much research interest owing to their applications in high-efficiency solar cells and light emission. Indeed, these solar cells not only show relatively high photovoltaic energy conversion efficiencies (above 22%), but can be also easily fabricated using cheap inorganic-organic perovskite compounds.

The formation of a dense and uniform thin layer on the substrates is crucial for the fabrication of high-performance PSCs. The concentration of defect states, which reduce a cell’s performance by decreasing the open-circuit voltage and short-circuit current density, needs to be as low as possible.

The research team reports that careful control of the growth conditions of perovskite layers with management of deficient halide anions is essential for realizing high-efficiency thin-film PSCs based on lead-halide-perovskite absorbers.

During the study the team demonstrated the introduction of additional iodide ions into the organic cation solution, which are used to form the perovskite layers through an intramolecular exchanging process, decreases the concentration of deep-level defects. The result showed that the defect-engineered thin perovskite layers enable the fabrication of PSCs with a certified power conversion efficiency of 22.1% in small cells and 19.7% in 1-square-centimeter cells. The new cells have been officially certified by the National Renewable Energy Laboratory (NREL).

Professor Seok remarked, “The key to manufacturing high-performance solar cells to reduce defects in materials that generate energy loss when converting sunlight to electricity. Our study presents a new method that suppresses the formation of deep-level defects, thereby setting a new record efficiency for PSCs.”

We’ll probably see these in the market fairly soon. The new products will offer smaller cell sizes and lighter weight. If they are redesigns from silicon cells they will also be lots less expensive. Welcome to the marketplace.


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