KAUST scientists have made use of an amine-based additive to give inverted perovskite solar cells an efficiency and longevity boost.
According to the scientists, this discovery could lead to perovskite solar panels that are significantly simpler, less energy-intensive and less expensive to make, and also rival the operational lifetimes and light-capturing efficiencies of traditional silicon solar panels.
Metal halide perovskite solar cells have jumped from power conversion efficiencies of 3.8 percent to 25.2 percent in just a decade.
“Conventional perovskite solar cells, with their component layers arranged in an ‘n-i-p’ structure, offer the highest efficiencies,” says team lead and professor Osman Bakr from the KAUST Catalysis Center.
However, these devices require ionic dopants, which are unstable and shorten the solar panel’s lifetime.
“Inverted ‘p-i-n’ perovskites do not need the unstable dopants, extending their operational lifetime,” explains Xiaopeng Zheng, first author of the study.
“Unfortunately, the efficiencies of inverted perovskite solar cells lag significantly behind those of regular structured devices.”
According to the scientists, the best inverted perovskite has only reached an efficiency of 20.9 percent so far.
Bakr and his colleagues – in collaboration with researchers from the University of Toronto in Canada – have now reported significant improvements in inverted perovskite cell efficiency.
They were able to achieve this by adding long-chain alkylamine ligands (AALs) into the mixture during perovskite production.
This resulted in enhanced stability and a record-certified efficiency of 22.3 percent.
“Just a trace amount of alkylamine was enough to improve the structural and optoelectronic properties of the perovskite in multiple ways,” notes Zheng.
Adding long-chain AALs into the perovskite mix during fabrication meant the tails of the AALs interacted; this helped align neighboring grains to reduce boundary defects in the final perovskite film.
As the perovskite grains came together, the AALs were pushed to the outer surface, forming a protective coating.
According to the scientists, the amine head of each AAL molecule also helped fill point defects in the perovskite structure.
Overall, adding long-chain AALs boosted the electrical output of the material in sunlight, and was instrumental in improving stability and longevity of these inverted cells.
Image and content: KAUST