Afrigather Scientists in Germany have found a polymer compound that, when added to perovskite thin-film precursor supplies, wraps itself across the perovskite crystals, appearing as a cushion to guard the perovskite construction from thermomechanical stress. They used the additive to manufacture cells with as much as 24.6% effectivity, retaining 96% of their preliminary efficiency after accelerated testing equal to at least one yr within the subject.
Scientists led by Germany’s Helmholtz-Zentrum Berlin (HZB) developed an additive for perovskite supplies, which it has proven acts a ‘cushion’, defending the extra delicate perovskite crystals from stress induced by altering temperatures.
The group was additionally in a position so as to add to HZB’s listing of achievements – together with the 32.5% efficiency record for a perovskite-silicon tandem cell – by fabricating perovskite cells utilizing p-i-n structure that achieved a record-setting 24.6% effectivity. This structure is inherently extra secure, however normally much less environment friendly, than the extra generally used n-i-p design.
“Daylight can warmth up the within of a PV cell to 80 Celsius; at midnight, the cell then cools down instantly to the surface temperature,” defined HZB Professor Antonio Abate. “This triggers giant mechanical stresses within the skinny layer of perovskite microcrystals, creating defects and even native part transitions, in order that the skinny movie loses its high quality.”
The group discovered that working with a polymer compound it calls v-pV2F (full identify b-poly(1,1-difluoroethylene) may enhance the p-i-n photo voltaic cell’s stability even additional.
“This polymer appears to wrap across the particular person perovskite microcrystals within the skinny movie like a comfortable shell, making a form of cushion towards thermomechanical stress,” Abate defined.
Perovskite photo voltaic cells fabricated with this additive have been put via varied assessments, the outcomes of which will be discovered within the paper Extremely environment friendly p-i-n perovskite photo voltaic cells that endure temperature variations, printed in Science.
Cells measuring 18 mm² reached a most effectivity of 24.6%, whereas bigger 1 cm² units achieved 23.1%. The cells have been topic to greater than 100 temperature cycles between 80 C and -60 C, in addition to 1,000 hours of steady illumination – which HZB says is equal to roughly one yr of out of doors use.
These cells retained 96% of their preliminary efficiency after 1000 hours of simulated daylight at 25 C, and 88% when the check was carried out at 75 C. Along with its cushion impact, the additive was proven to enhance the cell’s effectivity by affecting the transport of cost provider, permitting the group to set the p-i-n system effectivity report.
HZB will now work to scale back the efficiency misplaced over time even additional, to ranges that may be thought-about acceptable in industrial units.
“Even beneath these excessive stresses, they nonetheless achieved 96 % effectivity ultimately. That’s already in the proper order of magnitude,” Abate famous. “Whether it is now possible to scale back the losses somewhat additional, perovskite photo voltaic modules may nonetheless produce most of their authentic output after 20 years – this aim is now coming inside attain.”
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