China meets Michael Graetzel within the framework of the Global Energy Prize Laureate’s tour - 2017
Laureate of the Global Energy Prize Michael Graetzel continues his work within the framework of the 2017 laureate’s tour. Today he visited Zhejiang University (ZJU) in Hangzhou, which is one of the leading and oldest universities in China. During the lectures on perovskites, he presented the latest achievements of his laboratory in the field of solar energy production, told more about perovskite technology and its main differences from silicon batteries.
The scientist noted that one of the reasons that initially inspired him to engage in solar energetics, it is a fact that the annual amount of solar energy entering the Earth, a hundred times greater than the energy of all world reserves - and hydrocarbons, and renewable sources. Using only one hundredth of a percent of this energy could meet all the current needs of world energy, and half a percent can fully cover such requirements for hundreds of years ahead. Consequently, the potential of solar energy is inexhaustible, which dictated the need to seek solutions for the reasonable use of it.
Deepening especially in the development of perovskite solar cells, Michael Graetzel said that they came from molecular photovoltaics. The class of perovskite solar cells is an independent class of devices that appeared as a logical development of the Graetzel cells. The act of absorbing a quantum of light in Graetzel cells occurs when a dye molecule absorbs it, which is somewhat similar to the photosynthetic reaction. In perovskite cells, the quantum of light is absorbed by a bulk semiconductor (we are talking about the same perovskites), and the electron formed and the "hole" after this move each to its heterojunction.
As has been repeatedly mentioned, now such elements have reached an efficiency factor of 22.4 percent, they are very economical, since they use a thousand times less expensive materials that absorb light than silicon solar batteries and do not require energy-consuming processes such as smelting and purification of silicon. They have the potential for a multiple reduction in production costs, if the output is expanded. Important fact is that they can be made in low-temperature processes, and therefore - do not require, as in silicon photovoltaics, complex equipment.
As for the consumer qualities of both perovskite cells and Graetzel cells, in addition to their cheapness, they have a reserve of much greater functionality than silicon ones. Their important property is the ability to capture effectively a scattered light. Nevertheless, according to the laureate, perovskites are not suitable for large-scale power engineering, the power engineers need guaranteed work without degradation of the elements for at least ten years, and perovskite cells are not sufficiently durable for today.
However, in this case, we are talking about technologies that are progressing incredibly fast, and in the coming years, the problem of stability and longevity of the elements should be solved.