Efficient synthesis and characterization of C60 and C70 acetylacetone monoadducts for photochemical applications. Issue 7 (3rd July 2021)

• Record Type: Journal Article
• Authors: Iuele, Helena; Torres-Cortés, Sergio Alejandro
• Is Part Of: Fullerenes, nanotubes and carbon nanostructures. Volume 29:Issue 7(2021)
• Page Start: 556
• Page End: 566
• Publication Date: 2021-07-03
• Subjects: Fullerenes -- cyclopropanation -- photovoltaic efficiency -- monoadducts; Fullerenes -- Periodicals; Nanotubes -- Periodicals; Nanostructures -- Periodicals; 546.6812
• DOI: 10.1080/1536383X.2020.1868997
• Languages: English
• ISSNs: 1536-383X

Abstract

Abstract: 3′, 3′-Bis-acetyl 3′ H -cyclopropa[1, 9](C60 - Ih )[5, 6]fullerene and 3′, 3′-Bis-acetyl 3′ H -cyclopropa[8, 25](C70 - D5h(6) )[5, 6]fullerene monoadducts were obtained at room temperature via Bingel cyclopropanation reaction employing acetylacetone as ligand, DBU as base, carbon tetrabromide as intermediate for in situ formation of a bromomalonate and o -dichlorobenzene as solvent. Monoadducts were obtained with yields of 69% and 44% for C60 and C70 fullerene cages, respectively, and were purified on column chromatography by using silica gel as stationary phase and hexane, carbon disulfide (CS2 ) and chloroform (CHCl3 ) as mobile phase at r.t. Products were characterized by 1 H-NMR and 13 C-NMR spectroscopy, FT-IR, and UV-visible spectroscopies, MALDI-TOF mass spectrometry, OSWV and cyclic voltammetry (CV). Products exhibited irreversible reduction peaks controlled by diffusion processes in the interface of the probed cell, with LUMO energy levels of –3.9 eV and –3.13 eV for C60 and C70 monoadducts, respectively. These values are comparable with –3.09 eV of PC61 BM employed as standard. The obtained adducts were incorporated into inverted-type perovskite solar cells and were used as electron transporting materials giving power conversion efficiencies (PCE) of 8.5% and 14% for C60 and C70 monoadducts, respectively. It was observed that absorption in the visible spectrum improves replacing C60 fullerene by a fullerene with less symmetry, like C70 . GRAPHICAL ABSTRACT: