Solar see Hong Kong R & D power efficiency

Since entering the industrial age, human beings have been searching for better energy from burning coal, to oil and gas, and even hydraulics, wind power, and nuclear power. This involves a large number of important scientific research and inventions. Hong Kong University, State Key Laboratory of Synthetic Chemistry Zhiming, director of branch 973 research projects led by "basic and applied research of metal complexes excited state" to absorb "the excited state (Excited state)" under the sun around the chemicals come out The related photoelectric conversion and photocatalysis research, and hope to use solar energy as the ultimate solution to energy and environmental issues. Recently, the research team has succeeded in achieving a half chance of each photon to turn chemical molecules into excited states, and at room temperature, the lifetime of the excited state is further extended from the current one millionth of a second to thousands of times to five thousandths. Second, light energy has more time and more opportunities to be converted into electricity, making a very important breakthrough for future solar power generation.

Zhi Zhiming stated that the metal complexes in the study, that is, the compounds with metal, are considered to have better light-receiving properties (see the accompanying manuscript) and are common in daily life, including the chlorophyll necessary for plants to produce photosynthesis. There is also magnesium. The "excited state" is simply speaking, that is, after absorbing light, it has a high energy state.

He further explained that the purpose of the project is to use solar energy more effectively. "The central idea of ​​research is about energy and the environment. This is a problem faced by any place. With clean energy, there is a clean environment. What is clean energy? The most important thing is that there is no waste heat, no pollution, and solar energy is the best."

Sunburn "cooling" difficult to effectively store energy

In order to overcome the problem of transforming solar energy, Zhi Zhiming raised three major difficulties. First, it cannot effectively store energy. For example, when the hands are placed under the sun, the molecules of the hand absorb light and become excited, but it can only feel the heat and cannot control how this energy from the sun is used. He said: It will have no effect and eventually return to normal."

In addition, the stability of energy is also very important. Now that the sunlight is shining down, it has been producing an excited state. After absorbing light, the energy immediately falls, and it becomes “only hot and useless”. Therefore, one of Zhi Zhiming's research directions is to master the operation of the excited state more effectively, thereby transforming the sun's light energy and allowing the relevant energy to be applied. "But the difficulty lies in the fact that it must be able to absorb it in large quantities. Millions of photons can only absorb a few and it is useless."

Excited short-lived "doing nothing"

The most critical problem is that the excited state is too "short-lived", generally only in parts per billion. Zhi Zhiming described the “short life span as a matter of fact!” He said that the excited state can bring high energy, the oxidizing power can be comparable to that of an oxidant, and the reducing power is similar to that of a metal atom, but it needs to be applied, for example, converted into electricity. Must pass through, "These involve the second kind of object, must let them have the time to walk together". Although the lifespan of the excited state has been improved to one millionth of a second since the end of the last century, the time has already grown a lot, but Zhi Zhiming frankly stated that it is always difficult to use it effectively. And that is one of the reasons why solar energy is now converted into electricity.

Therefore, prolonging the life span of the excited state is an important issue for Zhi Zhiming's team. However, an important breakthrough has been made in the development of the 973 project for less than one year. “Now we do 5×10^(-3) seconds at room temperature (ie, 5 thousandths of a second) ), which is more than a thousand times more than before, and we have a 50% variable excited state for one photon." With regard to the stability of the excited state and the results of the extended life, a major step forward for solar energy conversion with more effective chemical materials will be achieved. Zhi Zhiming said with more confidence: “I believe this will be a successful project.”