Future of Solar Technology: Perovskite.
Perovskite is any material with the same type of crystal structure as calcium titanium oxide (CaTiO3), known as the perovskite structure, or XIIA2+VIB4+X2−3 with the oxygen in the face centers.[2] Perovskites take their name from the mineral, which was first discovered in the Ural mountains of Russia by Gustav Rose in 1839 and is named after Russian mineralogist L. A. Perovski (1792–1856). The general chemical formula for perovskite compounds is ABX3, where 'A' and 'B' are two cations of very different sizes, and X is an anion that bonds to both. The 'A' atoms are larger than the 'B' atoms. The ideal cubic-symmetry structure has the B cation in 6-fold coordination, surrounded by an octahedron of anions, and the A cation in 12-fold cuboctahedral coordination. The relative ion size requirements for stability of the cubic structure are quite stringent, so slight buckling and distortion can produce several lower-symmetry distorted versions, in which the coordination numbers of A cations, B cations or both are reduced.
The perovskite structure is adopted by many oxides that have the chemical formula ABO3.
A recent study, affiliated with UNIST finds key to produce a new cost-efficient way to produce inorganic-organic hybrid perovskite solar cells (PSCs) which sets a new world-record efficiency performance of 22.1 % in small cells and 19.7 percent in 1-square-centimeter cells.
This breakthrough comes from a research, conducted by Distinguished Professor Sang-Il Seok of Energy and Chemical Engineering at UNIST in collaboration with Professor Jun Hong Noh of Korea Research Institute of Chemical Technology and Professor Eun Kyu Kim of Hanyang University who both partook as co-authors of the study.
A key feature of this technology is its ability to fix the dominating defect in perovskite-halides, which is known to decrease the photoelectric efficiency. Their results, published online in the June 30th issue of 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.
"This study can improve the current record efficiency of perovskite solar cells from 20.1% to 22.1%," says Professor Seok. "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 (PSC) 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.
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.
In their study, the research 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 energy conversion efficiency of those PSCs with reduced defects is 22.1% and has been officially certified by the National Renewable Energy Laboratory (NREL).
"The key to manufacturing high-performance solar cells to reduce defects in materials that generate energy loss when converting sunlight to electricity," says Professor Seok. "Our study presents a new method that suppresses the formation of deep-level defects, thereby setting a new record efficiency for PSCs."
Perovskite solar cells is the emerging class of thin-film photovoltaic cells. Perovskite solar cell is a type of solar cell that comprises perovskite structured compound. The perovskite structured compound is mostly composed of hybrid organic-inorganic lead or tin halide-based material, as the light-harvesting active layer. These perovskite materials possess intrinsic properties such as broad absorption spectrum, fast charge separation, long transport distance of electrons and holes, and long carrier separation lifetime. These distinct properties possessed by perovskites make them promising material for manufacturing solid-state solar cells. The solar cell efficiencies of devices using these cells have increased significantly over the past decade due to the constant developments. Furthermore, these perovskite solar cells have the ability to absorb light across all visible wavelengths and are easily fabricated. Perovskite solar cells are sued in various applications such as smart glass, outdoor furniture, portable devices, and automotive and other electronic applications.
Perovskite solar cell aims to increase the efficiency of the cells and lower the cost of solar energy. Perovskite solar cells have the ability to reach a broad range of wavelengths of light. This allows them to convert more solar power into electricity. This is one of the major advantages of perovskite solar cells over the other conventional solar technologies. Furthermore, these solar cells offer properties such as flexibility, semitransparency, and lightweight. These characteristics of perovskite solar cells are expected to open new opportunities for various applications of solar cell. Currently, the common electrode material used in perovskite solar cells is gold. Thus, perovskite solar cells are costlier than other commercially used solar cells. This is expected to hamper the perovskite solar cell market during the forecast period. The cheaper perovskite solar cells available in the market have shorter lifespan. This further hampers the perovskite solar cell market. Toxicity of a substance called Pbl is another major issue restraining the perovskite solar cell market. Moreover, lead, which significantly pollutes the environment, is majorly used in most perovskite solar cells. However, the development of substitutes is expected to drive the perovskite solar cell market in the near future.
In terms of geography, the global perovskite solar cell market has been segmented into North America, Europe, Asia Pacific, Latin America, and Middle East & Africa. The perovskite solar cell market is anticipated to expand during the forecast period, led by an increase in electronic developments in countries such as Japan, China, India, and South Korea. Thus, Asia Pacific is estimated to lead the market during the forecast period. North America and Europe are the next attractive markets for perovskite solar cell due to the increase in solar energy practices in this region. The perovskite solar cell market in regions such as Latin America and Middle East & Africa is estimated to expand at a sluggish pace owing to the high development costs of these solar cells.
The perovskite solar cell market is highly consolidated, with a few global manufacturers and developers operating across the globe. Key players in the perovskite solar cell market include Saule Technologies, Fraunhofer ISE, Oxford Photovoltaics, Xiamen Weihua Solar Co.Ltd, Dyesol, and Front Materials.
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