What is an Organic Solar Cell?

Detailed explanation of the characteristics and structural principles of organic solar cells

Organic solar cells are solar cells that consist of organic materials at the core. It is mainly based on organic materials with photosensitive properties as semiconductor materials, and the photovoltaic effect generates voltage to form a current to achieve the effect of solar power generation.

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First, the characteristics of organic solar cells

As a new type of solar cell device, organic solar cells have the characteristics of flexibility, light weight, adjustable color, solution processing, and large-area printing preparation. They are currently a hot spot in the field of solar cell research. But low efficiency is the main reason that limits its large-scale application.

Second, the structural principle of organic solar cells

1. The principle of organic solar cells

Organic solar cells use photosensitive organics as semiconductor materials, and generate voltages to form currents by the photovoltaic effect. The main photosensitive organic materials have conjugated structure and conductivity, such as phthalocyanine compounds, porphyrins, cyanines, etc.

2. Several structures of organic solar cells

Organic solar cells can be divided into single junction structure, P-N heterojunction structure, and dye-sensitized nanocrystalline structure according to semiconductor materials.

3. Single junction structure

The single-junction structure is an organic solar cell made based on the principle of Schottty barrier. Its structure is glass/metal electrode/dye/metal electrode, which uses the different work functions of the two electrodes to generate an electric field. Electrons are transferred from the metal electrode with low work function to the electrode with high work function to generate photocurrent. Since electrons and holes are all transferred in the same material, the photoelectric conversion rate is relatively low.

4. P-N heterojunction structure P-N

The heterojunction structure refers to a heterojunction structure with a donor-acceptor (N-type semiconductor and P-type semiconductor). Among them, semiconductor materials are mostly dyes, such as phthalocyanine compounds and perylene tetraformaldehyde imine compounds, using the D/A interface (Donor—donor, Acceptor—acceptor) and electron-hole separation between semiconductor layers. The transfer characteristics in different materials increase the separation efficiency. Elias Stathatos and others combined the advantages of inorganic and organic compounds to make solar cells with a photoelectric conversion rate of 5% to 6%.

5. NPC (nanocrystaline photovoltaic cell) dye-sensitized nanocrystals

Dye-sensitized solar cell (DSSC) mainly refers to a type of solar cell that uses dye-sensitized porous nanostructured TiO2 film as the photoanode. It is a solar cell that mimics the photosynthesis principle of plant chlorophyll. However, NPC solar cells can choose appropriate redox electrolytes to increase the photoelectric efficiency, which can generally be stabilized at 10%, and nanocrystalline TiO2 is easy to prepare, low in cost, and has a considerable life span, which has a good market prospect.

Posted by Carrie Wong | WSL Solar Co., Ltd.

WSL Solar has been a quality and professional manufacturer of custom solar panels and solar solution provider in China since 2006.


210 Technology Replacement Demand Exceeds 20 Billion, HIT Leads the New Trend of Next-generation Photovoltaic Cells

In the face of the epidemic sweeping the world, the problem of “two-level differentiation” is in front of the photovoltaic people.

SMEs are struggling in a crisis-ridden environment and seeking hope for life, but for leading companies, it is still difficult to stop their pace of active expansion.

The leading domestic solar cell manufacturers are not afraid of the impact of the epidemic and are actively expanding production.

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Recently, Tongwei issued a fixed increase plan, which will raise no more than 6 billion yuan of funds, and it is expected that 4.2 billion will be invested in Meishan Phase II (7.5GW) and Jintang Phase I (7.5GW) high-efficiency solar cell projects.

In addition to Tongwei, LONGi has announced a total expansion of 10GW of monocrystalline solar cells, AiXu expanded by 5.9GW, Jingao expanded by 10GW, and Jinko expanded by 10GW. It is expected that PERC solar cell expansion will reach 30GW this year , The corresponding equipment amount is more than 6 billion, and it is expected to begin to place orders in Q2.

It is worth mentioning that the acceleration of the industrialization of 210 silicon wafers is still the main theme in 2020.

Judging from the announcement issued by Tongwei this year, the above projects are mainly based on the 210-size PERC technology route, and reserve space for PERC + / TOPCON equipment.

From the perspective of this year’s new expansion plan for solar cells, the expansion of solar cell factories led by Tongwei and Aixu are mainly based on 210 large sizes.

Among them, the first 210 solar cell workshop of Tongwei-Meishan Phase I is expected to be mass-produced in mid-May, and the follow-up Meishan Phase II and Jintang 30GW plans will take the 210 route.

In January, Axu announced the mass production of 5GW 210 solar cell production line. It also plans to expand its solar cell capacity to 22GW by the end of 2020, 32GW by the end of 2021, and 45GW by the end of 2022.

As for solar modules, Dongfang Risheng and Trina Solar have successively released 210mm 500W solar modules.

In addition, as the leader of 210 large silicon wafers, China Central also recently announced an investment of 5 billion yuan in the construction of G12 PERC + solar cell lines and shingled solar module projects, which will further promote the industrialization of large-scale silicon wafers.

Relevant institutions judge that the future increase in the penetration rate of 210 technology will exceed market expectations. It is expected that the industry replacement demand brought by large silicon wafers will exceed 20 billion, and Jingsheng Electromechanical as the only supplier of 210 single crystal furnaces will greatly benefit.

It is worth noting that as early as a few years ago, in the photovoltaic industry, there have been disputes between PERC, TOPCON and HIT technologies in the solar cell technology.

It is reported that PERC + is based on P-type silicon wafers and currently has a laboratory efficiency of 23.5% or more. It is necessary to superimpose 4 devices on the original PERC production line. It is expected that a prototype will be released by the end of 2020 and need to be verified by the production line.

TOPCON is based on N-type silicon wafers, with a conversion efficiency of over 23.5%. The equipment is relatively mature, but since N-type silicon wafers and equipment are relatively expensive, the overall cost is higher than PERC +.

The industry believes that the current conversion efficiency of PERC + / TOPCON can reach more than 23.5%, but the cost reduction route is still unclear. It needs to undergo production line inspection and is expected to become a transition path for PERC to upgrade to the next generation of technology.

In terms of HIT, it can be said that the progress has been quite effective. Taking Tongwei as an example, the average conversion efficiency of its multi-main grid starts at 23.5%, and it is expected to see more than 24% in the second half of the year, and the highest efficiency on the production line is close to 25%. But at present, it is still not comparable to PERC in terms of cost performance.

In 2019, in addition to the four HIT test projects of Tongwei and Shanmei International, battery factories such as Aikang and Artus have also successively launched HIT layouts since 2020.

The industry predicts that with the decline of HIT costs and the improvement of conversion efficiency in the next two years, HIT will become a megatrend for the next generation of photovoltaic solar cells.

Posted by Carrie Wong | WSL Solar

WSL Solar has been a quality and professional manufacturer of custom solar panel and solar solution provider in China since 2006.



Tongwei’s 6 Billion Yuan to Expand 210 Technology Routes, Net Profit Increased by 30% Last Year

Recently, Tongwei released a fixed increase announcement and performance report.

On the evening of April 20th, Tongwei issued a fixed increase plan, with a planned funding of no more than 6 billion yuan, for projects with an annual output of 7.5GW high-efficiency crystalline silicon solar cell smart factory (Meishan Phase II) and other projects.

Tongwei ’s additional funds raised this time are mainly used to invest in the Meishan Phase II and Jintang Phase I annual production of 7.5GW high-efficiency crystalline silicon solar cell smart projects. The proposed investment funds are 2 billion yuan and 2.2 billion yuan respectively; It is intended to be used to supplement working capital.

The above two major projects are planned to be implemented by Tongwei Solar (Meishan) Co., Ltd. and a newly established subsidiary respectively. The project adopts 210 large-size PERC solar cell technology routes. Upon completion, it will form an annual production capacity of 7.5GW of high-efficiency crystalline silicon solar cells . According to estimates, the construction period of the project is 1 year, and the production capacity will reach 90% in the first year of production, and 100% in subsequent years.

The implementation of this fundraising project will further expand the company’s solar cell production capacity, enhance and consolidate the company’s leading position in the global solar cell field.

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Since this year, Tongwei has announced its capacity expansion plan several times, with a total planned investment of 30 billion yuan.

In February, Tongwei threw out the largest single investment in history, planning to build an annual output of 30GW high-efficiency solar cells and supporting projects in Chengdu Jintang at 20 billion yuan. In March, the company announced that it plans to invest in a 40,000-ton high-purity crystalline silicon project in Baoshan City, Yunnan Province, with a total investment of 4 billion yuan.

Tongwei takes agriculture and solar photovoltaic as its main business, and has formed a business model of “agriculture (fishery) + photovoltaic” resource integration and coordinated development. As of the end of 2019, Tongwei has formed a high-purity crystalline silicon production capacity of 80,000 tons, of which monocrystalline materials account for about 90%; solar cell production capacity is 20GW, of which high-efficiency monocrystalline solar cells are 17GW.

According to the development plan previously released by the company, by 2023, the cumulative production capacity of high-purity crystalline silicon will reach 220,000 to 290,000 tons, and the cumulative production capacity of solar cells will reach 80 to 100GW.

In 2019, Tongwei achieved net profit growth.

Tongwei disclosed its annual report on the evening of the 20th. In 2019, it achieved operating income of 37.555 billion yuan, an increase of 36.39% year-on-year; net profit of 2.635 billion yuan, an increase of 30.51% year-on-year.

The overall photovoltaic business revenue was 17.8 billion yuan, an increase of 74.52% year-on-year. Among them, the operating income of solar cells and solar modules reached 12.27 billion yuan, an increase of 60.56 year-on-year; the gross profit margin was 20.21%, an increase of 1.52% year-on-year; the operating income of high-purity crystalline silicon and chemicals was 5.17 billion yuan An increase of 56.11% year-on-year.

In terms of high-purity crystalline silicon: Tongwei has formed a high-purity crystalline silicon production capacity of 80,000 tons and an ongoing capacity of 75,000 tons. With single crystal materials accounting for about 90%, various consumption indicators and costs continue to decrease. The total production cost of the first-phase project and the first-phase project of Baotou is 60,000 tons and the production cost is less than 40,000 yuan / ton.

For solar cells: The current solar cell production capacity is 20GW, of which the high-efficiency monocrystalline solar cell is 17GW, ranking first in the world.

However, Tongwei’s first quarter results released at the same time are not optimistic. In the first quarter, Tongwei’s net profit attributable to shareholders of listed companies was 344 million yuan, a year-on-year decrease of 29.79%.

Tongwei’s net profit fell in the first quarter. According to analysis, there may be two reasons:

First, Tongwei’s business is not only photovoltaics, but agriculture and solar photovoltaics as the main business, “agriculture (fishery) + solar photovoltaic” resource integration, collaborative development business model, although the photovoltaic industry in the first quarter The impact is limited, but the negative factors of agricultural fisheries will also have a certain impact on its profitability.

Second, in Tongwei’s business, overseas orders account for a relatively small amount. According to the annual report, the operating income of overseas regions only accounts for 5.42% of the total operating income. In contrast, in the first quarter of the domestic epidemic, when overseas epidemics had not yet fully erupted, Tongwei, which had a large domestic sales volume, was severely damaged.

Posted by Carrie Wong | WSL Solar

WSL Solar has been a quality and professional manufacturer of custom solar panel and solar solution provider in China since 2006.