Suppression of Boron-Oxygen related Light-Induced-Degradation effects in Solar-Silicon Solar Cells – BOLID

The cost reduction of the solar panels made from multicrystalline silicon could be achieved by using silicon feedstocks purified throughout metallurgical processes. In addition such processes could decrease the environmental impact (carbon balance, absence of polluting agent) of the solar panels fabrication process. Such solutions for the refining of the metallurgical silicon are under study in major international companies, and first results are promising since cells with conversion efficiencies of about 16% have been made from such feedstocks.
However, a major obstacle slow-downs the industrial development of these new purification processes. This issue is due to the fact that the efficiency of the cells made from these new materials is unstable under standard illumination. Indeed the efficiency strongly decreases under illumination (in few hours), the efficiency losses being equal to about 1-2 absolute %! This effect is known under the name of Light-Induced-Degradation (LID). These efficiency losses counterbalance the cost reduction offers by the use of this low-cost material and furthermore alter the commercial image of these cells.
The goal of the BOLID project is to solve these problems of LID, while maintaining high dopant concentrations in the feedstocks. To achieve this objective, the BOLID project will first develop a strong base of understanding on the properties of the BO complexes (responsible for the LID effects) in solar silicon. Then these understandings will be used to develop innovant and efficient “defect engineering processes” able to trap / passivate or suppress the species responsible for the LID process. This new processes will be then integrated to the industrial solar cells fabrication process.