Solar cells made with materials from the perovskite family are considered very promising for the market as they combine high performance and low cost. Furthermore, as they are flexible and light, they could be used to generate electrical energy from sunlight in objects such as curtains, backpacks and vehicle roofs – enormously expanding the application possibilities of photovoltaic energy.
But these emerging solar cells are not yet manufactured on an industrial scale, as there is no method that is both scalable and generates layers of perovskites of adequate quality.
An important step in this direction was taken by researchers from the Center for Innovation in New Energies (CINE) and collaborators, who adapted a simple and scalable process used in the production of materials and, with it, managed to generate the main layers that make up solar cells. perovskites.
The work was led by Ana Flávia Nogueira, professor at the State University of Campinas (Unicamp) and member of CINE. The results were published in the journal Industrial & Engineering Chemistry Research.
CINE is an Engineering Research Center (CPE) established by FAPESP in partnership with Shell.
“We carried out the process of manufacturing perovskite solar cells using modifications that could be easily applicable in a future production of these devices in an industrial environment”, summarizes Adriano dos Santos Marques, first author of the work, in an interview with the CINE Press Office.
The researchers explain that perovskite solar cells are formed by a “sandwich” of layers of different materials. The main ones are the photoactive layer, formed by a perovskite film that absorbs sunlight and converts it into electrical charges, and the transport layers, which conduct these charges to the electrodes.
In this new work, the group started with a scalable technique known as blade coating and optimized it to obtain perovskites with the quality necessary to compose solar cells with good energy conversion efficiency.
The technique is based on the action of a blade that, moved by a mechanical arm, uniformly spreads a solution over a substrate, forming a wet film. The thickness of the film is determined by several factors: concentration of the solution, speed of movement of the blade and size of the gap between the blade and the substrate. To make perovskite films, the solution used must contain the elements that will later form the perovskite and the solvent. When the solvent evaporates, the compound solidifies, forming crystals typical of the perovskite structure.
The biggest challenge in manufacturing these solar cells is mastering perovskite crystallization. In fact, when crystallization is slow, the films become more defective. The problem can be overcome by increasing the process temperature. However, this solution generates greater energy consumption and prevents the use of flexible materials as film substrates, as they deform with heat.
Considering these factors, the CINE researchers maintained a low deposition temperature (50 °C) and made adjustments to the composition of the solution, changing the solvents and precursors and regulating the proportion between them. After several attempts, they managed to generate perovskite films with the desired quality.
Furthermore, the group was able to use the same low-temperature blade coating process to produce the load-carrying layers. Solar cells assembled with this material achieved an efficiency of 14,3%, a very positive result for a process that brought together, for the first time, so many conditions compatible with the environment of the photovoltaic industry.
Read the article Low-Temperature Blade-Coated Perovskite Solar Cells.
*With information from the CINE Press Office.
original article published on the Agência Fapesp website
