1. Spin coating method
Spin coating is a simple and widely used laboratory preparation technique in which a perovskite precursor solution is dropped onto a substrate and rotated at high speed to evenly spread the solution, followed by heat treatment to form a thin film. This method is suitable for small-area devices and can prepare high-quality films, but there are problems such as serious solution waste and difficulty in controlling the uniformity of large-area films. Although high efficiency (e.g., 17.04%) has been achieved on small-area devices, its large-scale application is limited, and the process needs to be further optimized to achieve large-area fabrication in the future.
2. Silk screen printing method
The screen printing method transfers the perovskite solution to a substrate through a template, and the film is crystallized by heat treatment. Its advantages are simple process, low equipment cost, and suitable for large-area film preparation, but the film thickness and uniformity are difficult to accurately control, and the solution utilization rate is low. In 2014, the researchers optimized the screen printing process to prepare perovskite films with low defect concentrations, and the device efficiency reached 12.8%. Despite its potential for large-area preparation, film quality still needs to be further improved.
3. Scraper coating method
The squeegee coating method evenly coats the perovskite solution on the substrate with a squeegee and is suitable for large-area film preparation. It has the advantage of fast deposition speed, high throughput, and can be applied to flexible substrates, but the thickness and uniformity of the film are affected by factors such as the spacing between the squeegee blade and the substrate, and the viscosity of the solution. In 2016, researchers prepared large-area perovskite films by scraper coating with a device efficiency of 15.1%. This method shows a good application prospect in large-area preparation, and is expected to further improve the film quality through process optimization in the future.
4. Spraying method
The spray method involves atomizing a perovskite solution into tiny droplets and spraying them onto a substrate, followed by heat treatment to form a thin film. Its advantages are that it is suitable for large-area film preparation, the film uniformity is good, and the solution utilization rate is high, but the equipment cost is high, and the process parameters need to be accurately controlled. In 2015, researchers designed an ultrasonic spraying system to fabricate high-quality perovskite films with a device efficiency of 13%. The spraying method exhibits high reproducibility and uniformity in large-area preparation, and is expected to play an important role in industrial production in the future.
5. Slit coating method
The slit coating method is an industrial-grade thin film preparation technique in which a perovskite solution is uniformly applied to a substrate by means of a precisely designed coating head. The advantages are that the film thickness and uniformity can be precisely controlled, the solution waste is low, and it is suitable for large-area preparation, but the equipment cost is high, and the process parameters need to be optimized. In 2016, a perovskite thin film with an area of 25 cm² was prepared by slit coating with a device efficiency of 10.6%. This method has shown significant advantages in large-area preparation, and is expected to become the mainstream technology for the industrial production of perovskite solar cells in the future.
| Preparation method: | merit | shortcoming | Applicable scenarios |
| Spin coating method | The process is simple, the cost is low, and it is suitable for high-quality films in small areas | The solution is wasted, and it is difficult to control the uniformity of the film in a large area | Small area devices in the laboratory |
| Screen printing | The process is simple, the equipment cost is low, and it is suitable for large-area films | The thickness and uniformity of the film are difficult to control, and the solution utilization rate is low | Initial attempt at large-area films |
| Scraper coating method | Fast deposition and high throughput for large areas and flexible substrates | Film thickness and uniformity are affected by process parameters | Laboratories, large-area thin films and flexible devices |
| Spraying method | It is suitable for large-area films, with good uniformity and high solution utilization | The cost of the equipment is high, and the process parameters need to be precisely controlled | Large-area film and industrial production |
| Slit coating method | The film thickness and uniformity can be precisely controlled, and the solution waste is low, making it suitable for large-area preparation | The cost of the equipment is high, and the process parameters need to be optimized | Industrialized large-scale production |
