A research team led by Tom Moore of Arizona State University is truly imitating nature: capturing the sun's energy using "biological" cells rather than electrochemical cells. The plan uses artificial battery-like structures called “liposomes” as sunlight-capturing devices.
“Liposomes” are actually artificial structures that mimic chloroplasts, through which photosynthesis in nature takes place. The “liposome” has the same volume as the actual battery. The heart of this system is the trinary structure of molecules: 3 molecules are linked together by chemical bonds. One of them is a porphyrin molecule which absorbs solar photons well. the porphyrin molecule is when excited by light, electrons can be transferred to the second molecule in the trinity structure, the quinone molecule. The quinon moleculee then transfers the electrons to the third molecule which can freely “shuttle” within the phospholipid membrane. . After Moore's team demonstrated in 1998 that liposomes could generate protein energy, they added a key component that allowed the liposomes to use protein energy to drive chemical reactions and to use light sunlight to carry out chemical reactions. Moore's next goal is to produce NADPH (coenzyme nicotinamide adenine dinucleotide phosphate), an important energy reserve, which would be an important step towards the development of the first artificial leaves, and future artificial leaves will provide solar energy for a wide variety of chemicals. reactions.
Solar cells sensitized to dyes - Research history
A team of researchers from the Ecole Polytechnique de Lausanne (EPFL) has designed a newmethod for evaluating perovskites. To improve the stability of solar cells, they say this approach eliminates several drawbacks inherent in laboratory and outdoor testing of such devices.
The research team's method, described in the paper "Realistic operating conditions of perovskite solar cells under simulated temperature illumination," published in the journal Nature Energy, primarily simulates real-world conditions irradiation and temperature in the laboratory. conditions, which the researchers say eliminates the need for encapsulants and therefore allows them to eliminate failure mechanisms associated with the element rather than the perovskite material itself.
Meteorological data from a station near Lausanne was used to recreate real temperature and irradiation profiles in the laboratory on a specific day, allowing scientists to quantify the device's performance inreal conditions.
Recovery after degradation in the dark
Their results show that these perovskite structures are not subject to temperature and irradiation fluctuations of the “world real ". There is a significant impact, and, although battery efficiency suffers some drop in daylight, it recovers in darkness. This can be seen as solving the evidence stability problem that has long hampered the commercial development of perovskites. However, many obstacles to mass production relate to perovskite molecules exposed to humidity, a situation not addressed in the EPFL results.
The institute has studied the performance of perovskite batteries and its various aspects, including A leader in setting standards for measurements, including aging and degradation.
The term “stability” is used manifold"It is a very broad era and is evaluated in various ways, implying that different groups run different races," the research paper's summary reads. “For applications, energy is only available under realistic, long-term operating conditions. "
The history of dye-sensitized solar cell research dates back to early 19th century photography. In 1837, Daguerre produced the world's first photograph, Fox Talbot. is used in photo production, but because silver halide has a large bandgap and cannot respond to long-wave visible light, the photo quality has not been greatly improved. In 1883, Vogel,. a German expert in photoelectrochemistry, discovered that organic dyes can produce milky silver halide liquid is sensitive to longer wavelengths, which is the first report of the sensibi effect.lization of the dye. The use of organic dye molecules can expand the response range of silver halide photographic films to red light and even infrared bands, making it "panchromatic". "broad spectrum black and white. Film and even today's color film became possible. In 1887, Moser applied this dye sensitization effect to silver halide electrodes, extending the field's concept of dye sensitization from photography to the field of photoelectrochemistry The same dye was found to be effective in both photography and photoelectrochemistry. This was an important development in the field of dye sensitization, but the mechanism did not. It was not determined at the time, that is, it was not certain that awareness was achieved by transfer. It was not until the 1960s that the German Tributch discovered the mechanism. by which theDyes are adsorbed on semiconductors and generate current under certain conditions. Only then did people realize that electrons were moving from the ground state of the dye to the excited state. state under light and are then injected into the conduction band of the semiconductor. Photoelectron transfer is the fundamental cause of the above phenomenon. However, photoelectrochemical cells at that time used dense semiconductor films. , dyes can only be adsorbed in a single layer on the film surface. They can only absorb very little sunlight, and multi-layer dyes hinder the transmission of electrons, so the photoelectric conversion efficiency is very low and cannot reach the application level. Later, people prepared dispersed particles or electrodes with large surface areas to increase the adsorption of dyes. In 1988, the Grötzel group used a dye-sensitized polycrystalline titanium dioxide film with a roughness factor of 200 to prepare a solar cell. a Br2/Br-redox couple. A conversion efficiency of 12% was achieved under monochromatic light, which was the best result at the time. Until 1991, Grötzel, inspired by O'Regan, applied nanometers with large specific surface area prepared by. O'Regan's TiO2 particles enabled the battery efficiency to reach 7.1% in one fell swoop, achieving a major breakthrough in the field of dye-sensitized solar cells. /p>