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Abstract Careful analysis of the crystals formed in the reduction of AriPr8AlI2(AriPr8=C6H‐2,6‐(C6H2‐2,4,6‐iPr3)2‐3,5‐iPr2) with sodium on sodium chloride showed them to contain the long sought‐after dialuminene AriPr8AlAlAriPr8(1) that forms alongside the previously characterized alanediyl :AlAriPr8. The single crystal X‐ray structure of1revealed a nearly planar,trans‐bent C(ipso)AlAlC(ipso) core with an Al−Al distance of 2.648(2) Å. The molecular and electronic structure of1are consistent with an Al−Al double dative interaction augmented with diradical character and stabilized by dispersion interactions. Density functional theory calculations showed that the reactivity of :AlAriPr8with dihydrogen involves1, not :AlAriPr8, as the reactive species. In contrast, the reaction of :AlAriPr8with ethylene gave two products, the 1,4‐dialuminacyclohexane AriPr8Al(C2H4)2AlAriPr8(2) and the aluminacyclopentane AriPr8Al(C4H8) (3), that can both form from the aluminacyclopropane intermediate AriPr8Al(C2H4). Although the [2+2+2] cycloaddition of1with two equivalents of ethylene was also calculated to be exergonic, it is likely to be kinetically blocked by the numerous isopropyl substituents surrounding the Al−Al bond. Attempts to fine‐tune the steric bulk of the terphenyl ligand to allow stronger Al−Al bonding were unsuccessful, leading to the isolation of the sodium salt of a cyclotrialuminene, Na2[AlAriPr6]3(4), instead of AriPr6AlAlAriPr6.
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C 60 -based ionic salt electron shuttle for high-performance inverted perovskite solar modules
Although C60is usually the electron transport layer (ETL) in inverted perovskite solar cells, its molecular nature of C60leads to weak interfaces that lead to non-ideal interfacial electronic and mechanical degradation. Here, we synthesized an ionic salt from C60, 4-(1',5′-dihydro-1'-methyl-2'H-[5,6] fullereno-C60-Ih-[1,9-c]pyrrol-2'-yl) phenylmethanaminium chloride (CPMAC), and used it as the electron shuttle in inverted PSCs. The CH2-NH3+head group in the CPMA cation improved the ETL interface and the ionic nature enhanced the packing, leading to ~3-fold increase in the interfacial toughness compared to C60. Using CPMAC, we obtained ~26% power conversion efficiencies (PCEs) with ~2% degradation after 2,100 hours of 1-sun operation at 65°C. For minimodules (four subcells, 6 centimeters square), we achieved the PCE of ~23% with <9% degradation after 2,200 hours of operation at 55°C.
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- Award ID(s):
- 2339233
- PAR ID:
- 10592220
- Author(s) / Creator(s):
- ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; more »
- Publisher / Repository:
- Science
- Date Published:
- Journal Name:
- Science
- ISSN:
- 0036-8075
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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