Translated material
Quantum dots
Solar panels could become more efficient
The efficiency of solar cells can be increased from the current 30% to more than 60%, says Xiaoyang Zu, a chemistry professor at the University of Texas, in the latest issue of the journal Science. He and his assistants managed to significantly increase the production of electrical energy from solar energy using traditional solar panels.Today, the efficiency of the best solar cells does not exceed 31%. Such a low efficiency is explained by the fact that most of the solar energy is converted not into electricity, but into heat.
Thermal energy is lost in the form of so-called hot electrons. If it were possible to catch hot electrons, then the electricity output, at least theoretically, could be doubled - to 66%.
Creating an ideal solar battery, says chemistry professor Zu, consists of three stages. First you need to slow down the cooling process of hot electrons, i.e. make them release heat more slowly. This step has already been taken. Scientists found last year that semiconductor crystals are well suited to slow down the cooling process of hot electrons. Colloidal semiconductor nanocrystals give good results.
The second step is to catch the hot electrons and quickly use them before they lose all their energy. The most promising in this regard, Professor Zu is sure, are semiconductor nanocrystals or, as they are also called, quantum dots, fragments of a conductor or semiconductor, limited in all three spatial dimensions and containing conduction electrons.
Professor Zu and his colleagues also solved the second problem - they managed to extract hot electrons. In the experiments, they were efficiently transferred from lead selenide nanocrystals that make up the top layer of the solar cell to an electron conductor typically made of titanium dioxide. Scientists are confident that the problem can be solved using quantum dots made from other materials.
The creation of highly efficient solar cells with an efficiency of 66%, Xiaoyan Zu is sure, is not far off. The scientist is now working on solving the third problem - to minimize energy losses when transferring hot electrons to a conductor.