In recent years, thanks to the continuous improvement of photovoltaic-related scientific and technological levels, the photovoltaic power generation industry at home and abroad has developed rapidly and has gradually become the main form of clean energy utilization in most countries in the world. In the process of large-scale development of photovoltaic power generation, solar cells have experienced several important breakthroughs and iterative stages. Each step of development has laid a solid foundation for solar photovoltaic power generation to lead the future global energy green revolution.

1. Several major iterative processes in the development of solar cells

 (1) Early research In 1839, French physicist Alexandre Becquerel discovered the photovoltaic effect while assisting his father in studying the effects of irradiating light waves into electrolytic cells. In 1954, American scientists Chapin and Pearson first made practical single-crystal silicon solar cells at Bell Labs, and photovoltaic power generation technology with practical value was born. The New York Times called this breakthrough achievement "the beginning of a new era of unlimited sunlight serving human civilization."

(2) The first generation of solar cells 

From the 1960s to the 1970s, single-crystal silicon solar cells gradually became mainstream. This type of cell uses silicon materials to manufacture PN junctions to directly convert solar energy into electrical energy. In theory, it has relatively high conversion efficiency and stability. However, due to the high manufacturing cost and low energy efficiency of single-crystal silicon solar cells at that time, large-scale application was limited. In the 1980s, the production technology of polycrystalline silicon solar cells gradually matured and began to become mainstream. The difference between single-crystal silicon and polycrystalline silicon is that when the molten elemental silicon solidifies, the silicon atoms are arranged into many crystal nuclei in a diamond lattice. If these crystal nuclei grow into grains with the same crystal plane orientation, single-crystal silicon is formed; if these crystal nuclei grow into grains with different crystal plane orientations, polycrystalline silicon is formed. The main application scenario of silicon-based solar cells is centralized photovoltaic power stations. Currently, the technology is the most mature, but the photoelectric conversion efficiency has reached its upper limit, the room for efficiency improvement and cost reduction is relatively limited, and the marginal cost has increased significantly.

(3) Second-generation solar cells 

Second-generation solar cells are mainly made of various thin films. Thin-film technology requires much less materials than silicon solar cells, so it is easy to achieve large-scale production. The main types of thin-film cells currently include compounds such as cadmium telluride (CdTe), gallium arsenide (GaAs), and copper indium gallium selenide (CIGS). Compared with traditional silicon solar cells, thin-film solar cells have lower manufacturing costs and higher conversion efficiency, and are also easy to mass-produce.

 (4) Third-generation solar cells 

Third-generation solar cells must meet the following conditions: thin film, high conversion efficiency, and abundant raw materials. Perovskite solar cells are the most promising type of third-generation solar cells. Using perovskite materials as semiconductors can achieve higher efficiency. They are still in the laboratory and pilot stage, and their stability needs to be improved. With the advancement of science and technology in the future, they are expected to achieve commercial mass production.

2. Current status of cadmium telluride thin-film solar cells 

In the current thin-film solar cell market, cadmium telluride (CdTe) thin-film solar cells have the highest output and the most mature commercial technology.

Power-generating glass composed of cadmium telluride thin-film cells is flexible, thin, light, and transparent. It can be used in industrial and commercial applications such as curtain walls, sunrooms, carports, and bus shelters. It can also be used in industrial applications such as photovoltaic umbrellas, space capsules, automotive glass, and photovoltaic backpacks. It holds immense potential for development in multiple markets, including the construction, photovoltaic, and industrial sectors.

The basic structure of a cadmium telluride thin-film cell consists of five components: a glass substrate (for incident sunlight), a TCO layer (front contact) that transmits light and conducts electricity, an n-type window layer (forming a heterojunction), a p-type absorber layer (CdTe), a back contact layer, and a back electrode (reducing the contact barrier between CdTe and the metal electrode and connecting to the external circuit).

As the building-integrated photovoltaic (BIPV) market expands, the thin-film solar cell sector is seeking new market opportunities, striving to differentiate itself from crystalline silicon. In 2022, my country's cadmium telluride thin-film solar cell production was approximately 80 MW, and it is projected to reach 3,250 MW by 2029.

From the perspective of price, since 2020, the market price of cadmium telluride thin-film solar cells in my country has continued to decline, from 1.84 yuan/watt in 2020 to about 1.8 yuan/watt in 2021. By 2022, the average market price of cadmium telluride thin-film solar cells will further drop to about 1.78 yuan/watt. Overall, the price decline will gradually increase.

3. Development trend of cadmium telluride thin-film solar cells

Cadmium telluride thin-film solar cells have the advantages of light weight, good weak light performance, low temperature coefficient, high conversion efficiency, good durability, and easy large-scale production. In the future, the development trend of cadmium telluride thin-film batteries will mainly be reflected in the following aspects:

(1) Improving conversion efficiency: The photoelectric conversion efficiency of cadmium telluride thin-film batteries can reach 32% under ideal conditions. At present, the highest conversion efficiency in domestic laboratories is about 20%, and the highest conversion efficiency of cadmium telluride CdTe thin-film modules in mass production is 17.3%. In the future, improving conversion efficiency through further optimization of materials and process technology will be an important direction for the development of cadmium telluride thin-film solar cells.

(2) Reducing production costs: With the continuous advancement of technology, the production cost of cadmium telluride thin-film solar cells is gradually decreasing. Among them, the localization and large-scale production of core process equipment are the key to reducing costs. Secondly, the theoretical absorption layer thickness of cadmium telluride thin-film solar cells is about a few microns, and the raw material consumption is very small, so the manufacturing cost of cadmium telluride batteries is relatively low.

(3) Policy guidance and encouragement: In terms of policy, the state and governments at all levels have formulated relevant regulations, standards, subsidies, taxation and other policy measures to promote technological innovation, industrial upgrading and market expansion of thin-film solar cells.

(4) Expanding application areas: Cadmium telluride thin-film solar cell products can not only be used in conventional power stations such as ground power stations and rooftop split-type power stations, but their customized and specialized products can also be widely used in the BIPV field, new energy vehicle glass, new agricultural greenhouses and "photovoltaic +" scenarios. Each scenario contains huge market potential.

4. About the Company

Zoom Solar Green Energy Technology is a new energy high-tech enterprise specializing in the research, development, and production of thin-film solar cell chips, with a focus on cadmium telluride (CdTe) thin-film photovoltaic products. Zoom Solar Green Energy Technology's CdTe thin-film modules have achieved a domestically leading conversion efficiency of 17% in mass production. Over the next two years, Zoom Solar Green Energy Technology will invest 2.016 billion yuan in the Qinhan New City of Xixian New Area, planning and constructing a 300MW thin-film photovoltaic module production line. Focusing on technology incubation and technological innovation, the company aims to fill the gap in the development and application of CdTe solar cell technology in western my country with new technologies and processes.

5. Conclusion

Looking ahead to the future of solar cells, thin-film, low-cost, high-conversion efficiency, and abundant raw materials make them the ideal next-generation solar cells. With the continuous advancement of technology, we believe that CdTe thin-film solar cells will play an increasingly important role in the future renewable energy sector, bringing more green energy and a better life to mankind.