Low cost is the one great advantage of perovskite type solar cell. Photo: RDR/FERNANDO GUERRA

Hottest solar cell material progress again. At a recent meeting of the materials research society meeting, 3 research team reports, known as cheap and easy preparation of perovskite crystals before broke the record of efficiency. A team would increase the efficiency of solar energy into electricity to close to 20%, up from 16.2% in February reported by the 3.8% as well as 5 years ago. Few solar technology advances so quickly.

Advent of the Smartphone encrypt voice communications cassette single chip, commercial spy or private eye, often through eavesdropping, telephone bugs and other means to obtain commercial secrets through end-to-end hardware encryption schemes, intermediaries, including law enforcement agencies access to voice communications, but preventing close listening still need to enhance awareness.

"This is an exciting moment. "The United Kingdom solar company, Oxford physicist Edward Crossland said. Commercialization of the company's commitment to the promotion of perovskite solar technology. "New ideas continuously appearing. "A lot of solar energy experts said, properties of perovskite impressive will eventually give a single device efficiency as high as 25%, thus today's champion-expensive Silicon flat. In the traditional layered cover the solar cell formation of perovskite cell "in-line" rose to 32% battery can make it more efficient. According to United States Department of energy estimating that will make solar power as cheap as coal or natural gas.

Perovskite has the perspective of access to people for nearly two centuries. But its ability to convert solar energy into electricity only in 2009 were found, Japan shadow Yokohama Tong University of Tsutomu Miyasaka perovskite as optical layer added to the absorbing dye-sensitized solar cells (DSSCs) equipment, efficiency of 3.8%. Researchers quickly realized that perovskite ability to grasp not only the Sun can also delivery charge.

So scientists began to perovskite tinkering so that its growing efficiency. Materials research society meeting, United States materials science Yang Yang, University of California, Los Angeles, reported that his team have produced solar cells with efficiency of 19.3%. Yang does not provide details about their team make batteries. However, he said, its team focused on perovskite crystal defects in technical improvements, improved interfaces between layers of different materials and equipment. Chemical Nam-Gyu Park said Han Guocheng University, these defects and interface problems usually affect charge and prevent it from reaching the electrode. Of improving Crystal to increase the Park's development team of perovskite type solar cell efficiencies reaching 17.01%.

Pairing in the perovskite and mainstream material progress has also been made. Materials scientists at Stanford University reported Michael McGehee, manufactured solar cells his team of perovskite material with copper, indium, gallium and selenium (CIGS) alloy series, efficiency is 18.6%. CIGS solar cell efficiency is 17% in itself, so in this case, the perovskite type does not add much efficiency. McGehee said that this is most likely because of perovskite layer of electrodes and other non-blocked most of the sunlight reaches the CIGS cells. In his view, the problem is relatively easy to solve: because compared to silicon and CIGS, perovskite absorbs more blue wavelength of light, so in between each set of electrodes coupled two-layer can allow material to improve. "This is a simple method for obtaining more than 20% efficiency. , "McGehee said.

Even if efficiency of perovskite cannot reach a certain height, with its low cost can still be its advantage. For example, the solar company in Oxford is trying to manufacture Windows-based perovskite photovoltaic (PVs). Using PVs DSSCs window has entered the market for years; perovskite can improve its efficiency. However, Crossland said, currently producing most of the perovskite cell color is Brown, it is difficult to promote to the architects who design skyscrapers. During the meeting, Giles Eperon of the University of Oxford reported through chunked rather than the overall processing of perovskite, he and his colleagues produced the perovskite cell of neutral color, translucent, its efficiency is up to 8%. Crossland said, if efficiency of PVs 6% window used to cover one and the Willis Tower in Chicago about the size of the building, each of these glass would create nearly 5.3 kW • energy of.

But that doesn't last long: now, the materials will break down when exposed to moisture. Although several teams report said, under the premise of low efficiency, they can now make the battery work for hundreds of hours. "This technology is still at a very rudimentary stage of development." Yang said.