What is a perovskite cell
Perovskite solar cells (PSCs) are new compound thin-film solar cells that use perovskite materials as light-absorbing layers. The name of perovskite is taken from the name of Russian mineralogist Perovski, and the crystals with the structure of ABX3 and similar to it are collectively called perovskites. Perovskite solar cells, or perovskite solar cells, are solar cells that use perovskite-type organic metal halide semiconductors as light-absorbing materials.
Perovskite does not specifically refer to a certain compound containing calcium and titanium, but a general term for a class of crystalline materials with an ABX3 structure, and there are many types of materials to choose from.
The structure of a perovskite cell is mainly composed of the following key parts: a transparent conductive substrate, an electron transport layer, a perovskite light-absorbing layer, a hole transport layer, and a metal electrode. These components work together to enable perovskite cells to effectively absorb sunlight and convert it into electrical energy.
Transparent conductive substrate: This is the basis of perovskite cells. It is usually made of materials such as fluorine-doped tin oxide (FTO) or indium-doped tin oxide (ITO), which has high light transmittance and good conductivity. Its main function is to introduce sunlight and collect the generated current. The choice of transparent conductive substrate is crucial to the performance of perovskite solar cells because it not only affects the incidence of light, but also affects the extraction of current.
Electron transport layer: It is located between the transparent conductive substrate and the perovskite light absorption layer, and its main function is to transport electrons. Commonly used electron transport layer materials include titanium dioxide (TiO2), zinc oxide (ZnO), etc. These materials have good electron mobility and stability, and can transfer electrons generated in the perovskite light absorption layer to the transparent conductive substrate.
Perovskite light absorption layer: This is the core part of the perovskite solar cell, mainly composed of organic halide perovskite materials with ABX3 structure. These materials have excellent photoelectric conversion performance and can effectively convert the energy of sunlight into electrical energy. The preparation process and performance of the perovskite light absorption layer have a decisive influence on the overall performance of perovskite solar cells.
Hole transport layer: located between the perovskite light-absorbing layer and the metal electrode, its main function is to transport holes. Common hole transport layer materials include Spiro-OMeTAD, etc. These materials can effectively extract and transport photogenerated holes, thereby improving the photoelectric conversion efficiency of the cell.
Metal electrode: This is the last process of perovskite solar cells, which is mainly responsible for transferring charges and connecting external circuits. It is usually made by evaporating a layer of gold, silver or aluminum on the outside of the hole transport layer to improve the conductivity of the electrode.
The structural classification of perovskite solar cells is diverse, and each structure has its unique characteristics and applicable scenarios, usually including formal mesoporous structure, formal planar structure and trans-planar structure.
Development stage of perovskite cells
The development history of HJT cells can be divided into four stages: technology prototype period, technology accumulation period, rapid development period, and outbreak period
Advantages of perovskite cells
Compared with crystalline silicon, perovskite has three core advantages, namely high photoelectric conversion efficiency, abundant raw materials and easy synthesis, short production process, and rich application scenarios.
High photoelectric conversion efficiency
Data shows that the theoretical limit efficiency of single-crystal silicon cells is about 29%, while the theoretical efficiency of single-junction perovskite photovoltaic cells can reach 31%; perovskite stacked cells, including double-junction stacked cells of crystalline silicon/perovskite, can reach a conversion efficiency of 35%, and the theoretical efficiency of perovskite triple-junction cells can reach more than 45%, so it is considered by the industry to be the next generation of mainstream photovoltaic technology.
Rich materials and easy to synthesize
The basic raw material of crystalline silicon cells is polycrystalline silicon, which requires a lot of energy to purify the original silicon material. The production process of perovskite cells does not require silicon materials. The raw materials required for the production of metal halide perovskites are abundant and cheap, and the preparation of precursor liquid does not involve any complex process, and the purity requirements are not high. The subsequent components do not require high processing environment requirements. The component production process does not require the processing temperature of about 1,000 degrees of crystalline silicon cells. The energy consumption in the production process is relatively low, and most links do not require a vacuum environment. At present, the electrode material accounts for the largest proportion of the cost structure of perovskite components, reaching 37%, and the cost of perovskite materials itself accounts for only 5%. Perovskite components still have a large cost reduction space in the future.
Short production process
Crystalline silicon cells generally require four production and manufacturing stages: silicon materials, silicon wafers, cells, and components. This process takes at least 3 days, while the production process of titanium ore cells is simple. Glass, film, target materials, and chemical raw materials can be processed into components in a single factory within 45 minutes. The industrial chain is significantly shortened and the value is highly concentrated.
Rich application scenarios
Perovskite has the characteristics of light weight, flexibility, and high low-light resistance, and has a wide range of downstream application scenarios. Including photovoltaic buildings, power generation curtain walls, power generation stones, roof photovoltaics, mobile devices and electronic products, networked sensors, etc. With the advancement of technology, the application scenarios of perovskites are full of imagination.
Perovskite cell process
The preparation process of the light-absorbing layer of perovskite cells generally refers to the preparation process of thin-film photovoltaics such as silicon-based thin films and copper indium gallium selenide thin films, and is divided into two categories: wet process and dry process. Among them, the wet process includes slit coating and screen printing.
Usually, perovskite cell companies will try to conduct preliminary demonstrations of various technical routes in the laboratory stage. When moving towards a large-scale 100MW pilot production line, most companies currently use wet processes to prepare perovskite components, and a few companies choose dry processes or coating plus evaporation two-step processes.
In addition to the light absorption layer, the core layer of a single-junction perovskite cell also includes an electron transport layer and a hole transport layer. The deposition technology routes of the electron transport layer and the hole transport layer are relatively similar, basically including PVD (including magnetron sputtering and evaporation), reactive plasma deposition (RPD) and slit coating. At present, the mainstream routes for preparing perovskite core layers in the industry include PVD→slit coating (screen printing)→RPD (PVD), PVD→PVD (vapor deposition)→RPD (PVD), and PVD→slit coating + PVD (evaporation)→RPD (PVD). Different technical routes have advantages and disadvantages, and a unified technical route has not yet been formed.
Coating method perovskite cell whole line process flow
The coating method perovskite cell whole line production process is divided into front-end cell preparation and back-end component packaging, with a total of more than 30 links. The front-end process mainly includes front electrode preparation, laser scribing, perovskite light absorption layer, electron transmission, hole transmission, back electrode preparation, etc., among which the perovskite light absorption layer is the most critical. The back-end process mainly includes tape lamination, butyl adhesive coating, lamination and junction box welding, testing and other processes.
Perovskite cell enterprise layout
At present, perovskite cell technology has developed to the eve of commercial mass production. Many professional perovskite cell R&D and manufacturing companies such as GCL Optoelectronics, Xianna Optoelectronics, Jidian Optoelectronics, Wandu Optoelectronics, Renshuo Optoelectronics and other companies are actively promoting the commercial mass production of perovskite cell. The original crystalline silicon cell companies are actively promoting the research and development of perovskite and crystalline silicon dual-section cell.
Future development trend of perovskite cell
At present, the industry generally believes that the stacked cell composed of perovskite and crystalline silicon cell is an important technical direction in the future. Therefore, the industry is generally optimistic about the development trend of perovskite cell, and perovskite cell are also favored by photovoltaic companies and capital. The industry expects that the production capacity of perovskite cell will reach 461GW in 2030.
According to incomplete statistics, from 2023 to now, companies such as Pulse Energy, Zhongneng Photovoltaic Storage, Heijing Optoelectronics, Renshuo Photovoltaic, and Jidian Photovoltaic have a total of 15 financing events. The amount of financing ranges from tens of millions to hundreds of millions.
For perovskite cell technology, its biggest advantage lies in its future potential, which makes it have potential investment value, and therefore it is also valued by major capitals and investment banks.