Plugging performance-sapping defects that hamper perovskite performance

A multifunctional molecule that plugs assorted atomic-scale defects successful perovskite star materials tin importantly boost the longevity and electrical output of this promising star technology, KAUST researchers person shown.

Perovskites are an alternate solar-cell worldly to silicon. They typically comprise a operation of negatively charged iodine oregon bromine ions and positively charged pb and integrated ions. Adjusting the ion operation tin make wide bandgap perovskites that seizure the star wavelengths that silicon does not efficiently absorb. This suggests the 2 materials could beryllium combined successful tandem cells to seizure adjacent much vigor from the Sun.

However, perovskites inevitably diagnostic defects, specified arsenic wherever a peculiar ion did not slot into spot during fabrication, leaving a spread successful the structure. These reactive sites tin lend to accelerated show decline—unless they tin beryllium plugged. "Defect passivation is precise important for improving the semipermanent stableness of perovskite star cells," says Furkan Isikgor, a researcher successful Stefaan De Wolf's group.

Defect sites successful perovskites tin beryllium positively oregon negatively charged depending connected which ion is missing, but chemic additives for defect passivation tin typically plug 1 benignant of defect oregon the other. But a molecule called phenformin hydrochloride (PhenHCl) overcomes this problem, Isikgor, De Wolf and their colleagues person shown.

"PhenHCl works precise good owing to its multifunctional structure," Isikgor says. The molecule consists of an electro-positive ammonium caput radical that tin plug negatively charged defects and an electro-negative amine and imine radical assemblage to plug affirmative gaps.

The researchers showed that PhenHCl boosted the powerfulness conversion efficiencies (PCEs) of wide bandgap perovskites from 16.7 percent successful untreated cells up to 20.5 percent successful treated cells. "Moreover, PhenHCl passivation improves the PCE of textured perovskite/silicon tandem star cells from 25.4 percent to 27.4 percent," Isikgor says.

PhenHCl passivation besides importantly improved the stableness of the perovskite star cell. "Under continuous airy soaking, the PhenHCl-passivated instrumentality retained 80 percent of its post-burn-in ratio for astir 106 hours of operation," Isikgor says. The untreated instrumentality retained 80 percent of its post-burn-in ratio for lone 5 hours.

"Our elemental holistic defect-passivation strategy has drastically improved the semiconductor prime of solution-processed perovskites," says De Wolf. "Passivating the antithetic types of defects that whitethorn beryllium contiguous successful perovskites with a single molecule is highly charismatic for industry," helium adds. The adjacent measurement volition beryllium to integrate PhenHCl passivation with scaled-up perovskite production. "Simultaneously, we are moving connected further improvements successful instrumentality show and stableness done extended outdoor testing," De Wolf adds.

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