Knowledges

Introduction to Solar Cell Materials

Introduction to Solar Cell Materials

1. The development history of solar cells:

Since 1839, when Becqueral first observed the photovoltaic effect in chemical cells, people's research on raw materials for solar cells has never stopped. In the development process of solar cells, there have been various batteries of different structures, such as Schottky batteries, M1S batteries MINP batteries; Heterojunction cells (such as ITO (n)/Si (p), a-Si / c-si, Ge / Si), etc., in which homogeneous p-n junction cells eventually dominate. Solar cells are distinguished by materials including: crystalline silicon cells, TOPCon cells, amorphous cells, copper steel selenium batteries, pound pickaxe batteries, arsenide batteries, etc. Because silicon is the second most abundant element on the earth, the most mature technology, and the stable and non-toxic properties of crystalline silicon, it has become the main material for solar cell research and application.

2. Development of crystalline silicon solar cells:

The development of crystalline silicon cells is divided into three stages. The first stage: In 1954, Bell Labs developed a crystalline silicon cell with an efficiency of 6%, and the modern era of silicon cells began. In the following 10 years, the application of crystalline silicon cells continued to expand, and the process continued to improve. The second period began in the early 70s, during which the conversion efficiency of solar cells was greatly improved, and at the same time, the ground application of crystalline silicon solar cells was expanded, and the cost continued to decrease. In the early 90s, crystalline silicon cells entered a stage of rapid development, mainly to introduce surface passivation technology, reduce contact recombination effect, post-treatment to improve carrier life and improve the light-trapping effect in the manufacturing process of the battery. Battery efficiency has been greatly improved, production costs have been further reduced, and applications have been expanded.

3. Advantages of monocrystalline silicon solar cells

Since the mid-70s, crystalline silicon has dominated the raw material for solar cells. Solar cells are mainly divided into: monocrystalline silicon cells, polycrystalline silicon cells, and thin-film crystalline silicon cells. The emergence of polycrystalline silicon cells has reduced the manufacturing cost of solar cells, and its manufacturing equipment and manufacturing process are simple and have low material requirements. However, due to various defects in materials and processes, its conversion efficiency is low. Monocrystalline silicon cells use high-purity silicon as raw materials, grown by zone melting and purification method (FZ method) or lifting method (CZ method), and their average conversion efficiency can reach 24% left-stone, which is more than 5% higher than that of polycrystalline silicon solar cells.

4. The development trend of solar panels

With the development of the industry, the cost of monocrystalline silicon cells is getting lower and lower. Its performance is stable, the conversion efficiency is also making breakthroughs, and it has become the most important raw material for solar panels. From the perspective of solid-state physics, silicon materials are not the most ideal photovoltaic materials. Mainly because silicon is a bandgap semiconductor, its light absorption coefficient is low, so the study of other photovoltaic materials has also become a trend. Among them, cadmium telluride (CdTe), copper indium selenium (CulnSe2), and perovskite are considered to be three very promising photovoltaic materials, and some progress has been made, but there is still a long way to go from large-scale production and compete with monocrystalline silicon cells.