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Singapore scientists have reviewed all thermal evaporation techniques for the production of perovskite solar cells and modules. Despite the limitations, the new methods could lead to high production yields and more efficient products.
Scientists at the Institute of Energy Research at Nanyang Technological University in Singapore have investigated how thermal evaporation (TE) could be used to make mini perovskite solar modules. TE is a mature technique that is commonly used in the microelectronics and optoelectronics industries to fabricate organic light-emitting diodes (OLEDs), metal contacts, and coatings of various materials.
“We are looking at the use of various evaporation-based techniques to fabricate thin films of perovskite halides,” researcher Annalisa Bruno explained to pv magazine . “These range from relatively simple single-source deposition and multi-source coevaporation to more complex multi-step evaporation and hybrids of thermal evaporation with gas reaction and solution processing.”
According to her, this combined approach takes advantage of both methods. But she pointed out that it also has some limitations, such as increased complexity and the use of solvents.
“We believe that thermal evaporation is the ideal perovskite deposition method to make that leap quickly, as it is easily scalable, does not require hazardous solvents, and is already well integrated into current optoelectronics and microelectronics production lines,” Bruno said.
The researchers noted that one of the main problems with coevaporation is the need to thoroughly optimize the deposition parameters of perovskites with complex stoichiometries, especially when more than two or three precursors evaporate at the same time. They also pointed out how the long deposition time could be a barrier to commercial production, since most studies on these techniques tend to neglect this issue.
In their review they presented a series of techniques for manufacturing both perovskite solar cells and minimodules. These methods include single-step thermal evaporation, multi-step thermal evaporation, and multi-step hybrid deposition.
“It would be desirable to produce not only evaporated perovskite films, but also fully evaporated modules using the same manufacturing lines,” the group states.
Advantages of this method include a high degree of process control, precisely controllable film thickness, easy sequential addition of multiple layers, and the ability to process the substrate at low temperatures. The researchers state that the methods could also enable better purification of precursors during film formation, excellent spatial uniformity within device batches, good reproducibility across multiple manufacturing rounds, and high throughput throughput.
“The entire process can be automated and controlled, which makes it inherently attractive for large-scale, high-throughput manufacturing,” they say.
They described production techniques in " Thermal evaporation and hybrid deposition of perovskite solar cells and mini-modules ," recently published in Joule.
“We believe that the future of research in this field must seek new optimal interlayers for devices in order to improve the quality of the active material and transparency, passivating defects using vacuum-based techniques and boosting operational stability with the in order to maximize and harness the full potential of thermally evaporated perovskite solar devices,” said Bruno. |
