α-DTC₇₀ fullerene performs significantly better than β-DTC70 as electron transporting material in perovskite solar cells

Abstract

In this work, two new C70 isomers α and β bis(2-(thiophen-2-yl)ethyl)-C70-fullerene mono-adducts (DTC70) were synthesized, characterized and used as electron transporting materials (ETMs) in perovskite solar cells (PSCs).

Unveiling the regioselectivity of rhodium(I)-catalyzed [2 + 2 + 2] cycloaddition reactions for open-cage C70 production

“…This peak was assigned as a bis(fulleroid) compound by comparing the spectra with the UV–vis absorption pattern exhibited by previously characterized C 70 bis(fulleroids) reported by Murata et al [ 43 , 48 ]. In addition, a minor peak at a retention time of 20 minutes was also observed in the HPLC chromatogram, whose UV–vis has a pattern that is similar to a previously reported α-adduct [ 49 ]. We reasoned that this minor compound was the cyclohexadiene-fused C 70 intermediate, analogous to cyclohexadiene-fused C 60 I (see Scheme 1 ), which had not completely evolved into the corresponding bis(fulleroid) product after 4 h of reaction (Figure S1 in Supporting Information File 1 ).…”

Targeted Molecular Design of Functionalized Fullerenes for High‐Performance and Stable Perovskite Solar Cells

“…[ 101 ] Besides, they also reported two new C 70 isomers, α‐ and β‐bis(2‐(thiophen‐2‐yl)ethyl)‐C 70 ‐fullerene mono‐adducts (DTC 70 ). [ 102 ] As exemplified by DFT calculations, α‐DTC 70 showed a shorter distance between perovskite surface and fullerenes as well as a higher absorption energy between perovskite surface and addend groups, demonstrating the stronger interactions between α‐DTC 70 and perovskite than those of β‐DTC 70 , and in turn, led to an optimal photovoltaic performance of the PSCs. Unlike the fullerene multi‐adducts discussed in the last section, the main products of functionalized [70]fullerenes here (namely α‐isomers) with smaller energy disorders seem to show better photovoltaic performance than β‐isomers or other secondary products, pointing at a meaningful direction for synthesis, purification, and exploration in the future.…”

Recent Advances in Functionalized Fullerenes in Perovskite Solar Cells†

“…The photovoltaic performance discrepancy of different isomers indicates that the PCE of inverted PSCs is sensitive to the steric configuration of functionalized fullerenes, showing that devices with α‐DTC 70 ETL exhibit a higher PCE and improved long‐term stability than their counterpart β‐DTC 70 due to the better ability to extract electrons. [ 38 ] In 2020, Wang et al . innovatively developed a novel tetrafunctionalized fullerene 2b by electrochemically generated dianionic strategies.…”