Silicon flexible solar cells

Researchers have demonstrated an innovative method for producing flexible solar cells from silicon (silicon) that are twenty-four percent more efficient than the cells known today and can still be rolled like a sheet of paper * The findings could allow the use of solar cells in applications that today use more expensive alternatives of thin surfaces.

[Translation by Dr. Moshe Nachmani]

A crystalline form functions as a semiconductor that includes an indirect bandgap, which means that the photon moves an additional distance before being absorbed to form an electron-hole pair, this in known materials, for example, gallium arsenide or perovskite. Many researchers claim that these structures are not suitable for creating flexible or bent solar cells. However, researchers from the Australian National University in Canberra argue that this argument is wrong, and that a thin sheet may create flexible or bent cells either by spacing the cell units within a flexible infrastructure or by creating gaps in the structure. Researchers from the Shanghai Institute of Microsystems and Information Technology, of the Chinese Academy of Sciences, started with wafers 160 micrometers thick, using a concentrated basic solution to eat the wafer to obtain wafers of varying thicknesses. A smooth slice 60 micrometers thick was as flexible as a piece of paper. Unfortunately, given the glossy nature of the surface, it also reflects about thirty percent of the light that reaches it. Therefore, the researchers used a dilute alkaline solution to create tiny structures of pyramids on the outer surface. These structures significantly reduce the return capacity, but also increase the fragility of the material. "For a long time, people struggled with the balance between light reflectivity and flexibility, which explains why most of the efficiency percentages of solar cells based on flexible crystalline form were quite low," explains one of the researchers. 

Using a super-fast video camera, the researchers found that the cracks always start forming at the edges. Therefore, the researchers removed the structures at the edges by immersing them in a mixture of acids. As a result, the slices regained their flexibility. The researchers found that the smooth areas dispersed the stress, allowing the rough areas to form a network of microcracks instead of discrete fractures at a defined point. Solar cells created from these slices demonstrated a solar efficiency of over twenty-four percent of those existing today, while maintaining this efficiency even after various pressure tests. "It was completely self-evident that the grooves in the surface structure of the forge slice were a great concern and this article demonstrated this well and showed that if you get rid of the rough structure and the edges then the rate of breakage decreases significantly," said one of the experts in the field.

One of the researchers from the Netherlands explains: "The Netherlands is a very populated country, and we must take advantage of the infrastructure and buildings that already exist in the country for the utilization of solar energy. The truth is that the market for flexible cells is currently small, but many efforts are being made in Europe and Asia to increase this market." She adds and says that she believes "that the authors of the article did not invest enough to explain how important this mechanism is", while noting that increasing the flexibility of the cells could reduce the need to encapsulate them in heavy glass, thus allowing the installation of flexible solar sheets safely on Roofs and windows in buildings.  

The article describing the study

More of the topic in Hayadan:

• Nano Israel: Technion researchers have developed a new method for compressing light waves, which will improve the resolution of existing microscopes and the printing of electronic applications
• The illuminated chips method