Benzo[c]thiophene–C₆₀ Diadduct: An Electron Acceptor for p–n Junction Organic Solar Cells Harvesting Visible to Near‐IR Light

Abstract

We synthesized a new 56-π-electron fullerene derivative through a Diels-Alder cycloaddition of benzo[c]thiophene that featured a relatively low temperature, closer to stoichiometric use of the diene, and easy product purification. The 56-π-electron benzo[c]thiophene diadduct (BTCDA) has a LUMO energy level of 0.09 to 0.18 eV higher than that of 58-π-electron fullerenes, and therefore, the BTCDA-based organic photovoltaic device exhibited a higher open-circuit voltage and power-conversion efficiency (PCE). When used with a binary-donor system, including visible-light-harvesting tetrabenzoporphyrin (BP) and near-IR-harvesting titanyl phthalocyanine (TiOPc), the device had a PCE that was 1.5-3 times higher (2.8%) than that for devices with BP or TiOPc alone because the binary-donor device can utilize light between λ=350 and 950 nm.

A Review on Fullerene Derivatives with Reduced Electron Affinity as Acceptor Materials for Organic Solar Cells

“…Compound 169 contains the bridging sulfur atom in the structure of an indene analogue attached to the fullerene cage [148]. The cyclic voltammogram showed a shift of the first reduction potential to the cathodic region by 40 mV versus [60]PCBM.…”

“…Adduct 170 based on fullerene C 70 is an analogue of compound 168 and showed an increase in V OC of the corresponding devices by 80 mV, while the cell efficiencies remained comparable to those of the reference devices based on [60]PCBM/P3HT [135,148]. R. Tao et al developed the fullerene derivatives containing two indene fragments, one of which is directly linked to the fullerene skeleton (compounds 171 and 172) [149,150].…”

“…Using the obtained trisadduct in photovoltaic devices, it was possible to increase the V OC values by 300 mV as compared to the P3HT/ [60]PCBM reference cells, but other parameters deteriorated. Fullerene derivative 332, representing an analogue of compound 331 with sulfur atom in the indene bridge, has only been studied electrochemically [148]. The first reduction potential of compound 332 shifted to the cathodic region by 310 mV versus [60]PCBM.…”

Striking Effect of Polymer End-Group on C60 Nanoparticle Formation by High Shear Vibrational Milling with Alkyne-Functionalized Poly(2-oxazoline)s

“…Buckminsterfullerene (C 60 ) and other fullerenes were first discovered by Kroto et al . in 1985 and later made accessible in large quantities by Krätschmer et al Ever since, fullerenes have been the subject of extensive research due to their unique properties for material science and biomedicine. − In biomedicine, in particular, the antioxidant and photosensitizer properties of C 60 have been used for the treatment and prevention of cancer and several other degenerative diseases linked to oxidative stress. − Other than the treatment of degenerative diseases, fullerenes have also been applied in the areas of diagnostics, radioprotection, HIV-1 protease binding, and antibacterials. − Despite this biomedical application potential of C 60 , its negligible water solubility leads to extremely low bioavailability . Several approaches to overcome this issue have already been developed, namely, utilizing chemical modification, cosolvent evaporation or intermolecular complexation to generate water-soluble fullerene derivatives, dispersions, or (nano)­composites. − In general, intermolecular complexation offers the most elegant solution, as it allows the synthesis of functional fullerene composites with a high degree of complexity, without generating a new C 60 derivative with unknown toxicological profile nor having to cope with the complex regio- and stereoselectivity during chemical modification of C 60 . ,, …”