Polaris solar PV net news: solar cells are semiconductor devices that can convert light energy into electricity, which is the photovoltaic effect (photovoltaiceffect). Take advantage of this effect, solar cells to convert solar energy into electrical energy. Therefore, the cell conversion efficiency higher, we can gain more power. So the main goal is to constantly strive for higher conversion efficiency of solar cells.

Usually we see in the solar panels, is made of crystalline silicon material. This kind of crystalline-silicon solar cells from began its development in the 1970 of the 20th century to the present, photoelectric conversion efficiency of up to 25%, after nearly 50 years of this period of time. And hottest research areas is perovskite-type methylamine PB-iodide thin-film solar cells (hereinafter perovskite-type solar cells), 5 years from 2009 to 2014, photoelectric conversion efficiency jumped from 3.8% to 19.3%, improving by a factor of 5 times. Progress of perovskite-type solar cell conversion efficiency so great and cheaper and easier to produce than traditional silicon cells, Science (Science) journal 2013 rated it as one of the top 10 scientific breakthroughs.

United States national renewable energy laboratory (NationalRenewableEnergyLaboratory,NREL) published by early 2014, all kinds of solar cell conversion efficiency record. Current record for the highest conversion efficiency concentrator type triple junction solar cells is manufactured by sharp created, up to 44.4%. Described in perovskite-type solar cells being counted as 17.9% (see circled in the picture) and perovskite-type solar cell conversion efficiency has been at the University of California, Los Angeles Professor Yang Yang’s team improved to 19.3%.

Perovskite-what is it?

In Russia he discovered calcium Titanium Ore, hidden in the Harvard Museum of natural history Credit:La2O3 (CCBY-SA3.0license).

Perovskite (perovskite) is Germany mineralogist Gustav ˙ Ross (GustavRose) in 1839, in Russia on the territory of the Central Ural mountains found perovskite rock samples, decided to use his great geologist named LevPerovski in the heart of this ore [4]. The ore is a normal crystal of organometallic compounds, mainly composed of calcium titanate (CaTiO3). Later, people referred to the perovskite cell, not with his discovery of the ore material is made of, but using similar compounds with perovskite crystal structure.

Perovskite crystal structure diagrams

The structures of perovskite is ABX3 form. Sharing a BX6 in every corner of this structure is octahedral, where b is the metal cation (Sn2+ or Pb2+), x is an anion (Cl-,Br-or I-). Cation in perovskite a material to be used to offset charges reached electrically neutral, alkali metal ions which can be a large RADIUS, and can even be a molecule. This particular crystal structure so that it has a lot of unique physical and chemical properties, such as draw optical, electro-catalytic properties, and so on, in the field of chemistry, physics, has a small application. In the perovskite family now includes hundreds of substances, from conductors, semiconductors, insulators, very wide, many of which are synthetic. Solar cells using perovskite (such as CH3NH3PbI3, CH3NH3PbBr3 and CH3NH3PbCl3) belong to the semiconductor, have good light absorption.

5 years, from 3.8% to 19.3%

In 2009, Gong Banli shadow Yokohama Tong University (TsutomuMiyasaka), lead by a thin film of perovskite (CH3NH3PbI3 and CH3NH3PbBr3) as a light absorbing layer used in dye-sensitized solar cells, produced the perovskite-type solar cell. Photoelectric conversion rate at that time was 3.8%. Later researchers have improved the battery converted to over 1 time. Conversion efficiency, but also face a deadly problem-perovskite metal halide easily hydrolyzed liquid electrolyte in the battery led battery low stability, short life. [6]

In August 2012, gelazier (Gr which tzel) leadership has been achieved by Sungkyunkwan University and Polytechnic of Lausanne laboratory will be a solid hole transport materials (holetransportmaterials,HTM) into solar cells, cell efficiency improving to 10%, but also solves the problem of unstable batteries, new type of perovskite-type solar cells with liquid electrolyte is easier to package than before. After that, the perovskite-type solar cells become the new hot spot.

Graz’s laboratory in nature, 2013 (Nature) published papers in journals, observed by scanning electron microscope of the perovskite cell cross-sectional images. Sequentially from the top down is gold (anode), HTM hole transport layer, TiO2/CH3NH3PbI3 (perovskite), FTO transparent conductive glass, as well as at the bottom of the glass.

In an endless stream of perovskite-type solar cell-related study, scientists also found that perovskite suck not only is good, is also a good charge transport material. They continued by improving structure of perovskite materials and to improve photoelectric conversion rate of the perovskite cell. In the same year, Oxford, Henry ˙ Si Naisi (HenrySnaith) battery of TiO2 use in aluminum (Al2O3) is replaced, perovskite is not only the absorption of light in the cell layers, also can be used as transmission charge of semiconductor materials. Thus, of the perovskite cell conversion efficiency rose to 15%[8]. Si Naisi said “development of perovskite-type battery so fast, I feel that this record may soon be broken. ”

Sure enough, in August this year, at the University of California at Los Angeles team led by Chinese scientists like Yang Yang, in science (Science) journal, according to a new research paper, through improved perovskite layers, select the material more suitable for transmission charge for the battery at both ends of the electrodes can collect more. In this study, perovskite-type solar cell conversion efficiency of up to 19.3%[9], became the area’s largest.

The clean energy of the future?

Although we have been able to mass production conversion efficiency of up to 25% of crystalline silicon solar cells, and conversion efficiency 17% of CIGS (Copper-Indium-Gallium-Tin), solar cells, but we should be aware that when the solar panels to generate clean energy, its production cost is not low in production of raw materials can also cause a certain degree of environmental pollution. Other organic thin-film solar cell and solar cell conversion efficiency of organic-inorganic hybrid is still at around 10%.

Perovskite-type solar cell conversion efficiency not only has obvious advantages, the production process is relatively simple. Laboratories often use liquid phase deposition, vapor deposition techniques, mixing and liquid/vapor deposition process. Therefore, the cheaper and easier to manufacture in perovskite-type solar cells, is likely to change the whole pattern of solar cells. From now on, its power generation costs and could even be lower than the thermal power.

However, we are not in a hurry to it “for life” wants to realize the tremendous business value of perovskite-type batteries, there are 3 challenges to be addressed:

Poisonous. Perovskite materials contain lead, which is a hazard to humans and the environment have a great element. United States Northwestern University have developed a Tin replace lead perovskite-type solar cells, but the cell conversion efficiency are only 6%. This battery is still in the early stages of development, in the future there may be room to improve efficiency;

Unstable. Lead oxidized perovskite volatile, and when the crystals, water is easy to decompose. If we use the perovskite cell generation, it may seep into the roof or in the soil, a threat to the environment;

Life is not long. Currently, the longest life expectancy of perovskite-type solar cells can be up to 1000 hours, cooperation in research and development by the Huazhong University of science and the Lausanne Federal Polytechnic. While traditional crystalline silicon solar battery life and can be up to 25 years, much longer than the perovskite cell.

Although perovskite future difficulties, but in today’s energy shortage, people will not give up any chance of new energy. Maybe one day, humans will rely on it to provide electricity. (Edit: haematococcus pluvialis)

Original title: rapid development of perovskite-type batteries, you will become a dark horse in the solar industry?