The Canadian scientists have discovered a promising production technology for gallium arsenide solar cells. Growing cells directly on silicon substrates is a promising strategy that can reduce the excessively high production costs of certain technologies. By using porous silicon, scientists can take a big step towards the goal of producing high-performance III-V solar cells at a lower cost.
Gallium arsenide (GaAs) and other III-V materials (named according to their groupings in the periodic table) are well-known high-performance solar cell materials, and they occupy most of the seats in the comprehensive record of conversion efficiency.
But their production costs, which are usually hundreds of dollars per watt, mean that these batteries are limited to driving satellites, drones and other niche areas where battery performance takes priority over the cost per watt of power generation capacity. Reducing production costs to a level where mainstream solar applications can take advantage of their performance potential is a very important issue. In recent years, scientists have proposed some methods to achieve this goal.
Growing GaAs layers on silicon substrates is a very promising way to eliminate expensive germanium raw materials while allowing larger-scale production. However, the battery layer produced by this method has many defects, which limits the performance in solar cells.
Scientists led by the University of Sherbrooke in Canada have conducted research on whether replacing crystalline silicon (c-Si) with porous silicon can bring improvements. The results of this survey were published in the journal "Solar Materials and Solar Cells". The results showed that using porous silicon instead of crystalline silicon in other consistent processes can achieve a significant increase in fill factor and open circuit voltage.
Nano heterogeneity epitaxial ;
The team used a process called Nano Hetero-Epitaxial (NHE) to grow semiconductor layers on patterned substrates. The team used a two-step growth process. First, a GaAs buffer layer was grown to bridge the pores of silicon, and then the main film was deposited at a temperature of 565°C.
Cells grown on porous silicon with a size of 1×1 mm have a fill factor of 56%, while those grown on crystalline silicon have a fill factor of 41%. The team attributed this to fewer defects in the material, resulting in lower reorganization and parasitic losses.
The team pointed out that the defect level of the produced battery still needs to be further reduced in order to achieve favorable battery performance, and said that increasing the porosity of silicon to make it more flexible and better optimizing the buffer layer in the two-step growth process are all worthwhile Directions for further research.
The original text comes from PV MAGAZINE.