High LUMO energy pyrrolidinofullerenes as promising electron-acceptor materials for organic solar cells

Abstract

We report the synthesis and investigation of four novel pyrrolidinofullerenes bearing electron donating alkoxyphenyl substituents. Cyclic voltammetry studies revealed that the designed fullerene derivatives have reduced electron affinity compared to the conventional material [60]PCBM. The organic bulk heterojunction solar cells based on the pyrrolidinofullerenes and P3HT revealed impressive open-circuit voltages of 700-780 mV and enhanced light power conversion efficiencies with respect to the reference PCBM/P3HT devices. The designed materials demonstrated also reasonably good compatibility and decent photovoltaic performances in combination with the carbazole-thiophenebenzothiadiazole copolymer PCDTBT.

Overcoming the Thermal Instability of Efficient Polymer Solar Cells by Employing Novel Fullerene‐Based Acceptors

“…In contrast to PCBM, during the same temperature range, PyF5 exhibits a broad endothermic feature during the first heating run, implying it being a dominantly amorphous material. This is most likely because PyF5 is a mixture of two stereoisomers due to hindered nitrogen inversion . A melting peak was observed in the first heating scan of pristine FAP1, indicating the crystalline‐feature of FAP1.…”

Tether‐Directed Regioselective Synthesis of an Equatorialface Bisadduct of Azafullerene Using Cyclo‐[2]‐octylmalonate

“…[23][24][25] The model compound [6,6]-phenyl C 61 butyric acid methyl ester (PCBM), aw idely adopted electron acceptori n bulk heterojunction (BHJ) solar cells, has ah igherL UMO level (À4.08 eV) than that of pristine C 60 (À4.20 eV), and the addition of asecond malonate unit, formingabisadduct, furtherincreasest he LUMO energy (À3.97 eV). [32] In the case of C 59 N, addition of the first malonate moiety decreases the LUMO energy by 0.06 eV,s pecifically from À3.89 eV for (C 59 N) 2 to À3.95 eV for monoadduct 2.T his is analogous to observations in previous studies, [6,7] with opposing trends being reported forC 60 monoadducts. Addition of the second malonate to C 59 Nf orming bisadduct( AE)-3 raises the LUMO level to À3.81 eV,0 .08 eV higher than that of the parent (C 59 N) 2 .A ll redox data for (C 59 N) 2 ,m onoadduct 2,a nd bisadduct( AE)-3 are collected in Ta ble S2 (Supporting Information).…”

“…The redox properties of (AE)-3 were screened by cyclic voltammetry.B isadduct (AE)-3 exhibits one irreversible wave at À1.17 Va nd three quasi-reversible reduction waves at À1.29, À1.73, and À2.20 V vs. Fc + /Fc (Figure 5b), which are about 140, 140, and 40 mV more negative than those for monoadduct 2.N otably,t he C 59 N-centred reduction potentials of (AE)-3 appear at more negative values than those reported for C 60 bisadducts. [23][24][25]32] It is also known that for mono-andb is-cyclopropanateda dducts of C 60 the LUMO level tends to drift to highere nergies. [23][24][25] The model compound [6,6]-phenyl C 61 butyric acid methyl ester (PCBM), aw idely adopted electron acceptori n bulk heterojunction (BHJ) solar cells, has ah igherL UMO level (À4.08 eV) than that of pristine C 60 (À4.20 eV), and the addition of asecond malonate unit, formingabisadduct, furtherincreasest he LUMO energy (À3.97 eV).…”

Research in the Field of Organic Photovoltaics at the Institute for Problems of Chemical Physics of Russian Academy of Sciences

“…Fig. 18 shows that use of a properly designed fullerene derivative instead of PCBM improves both open circuit voltage and efficiency of organic bulk heterojunction solar cells [131]. Methanofullerenes bearing cyclopropane ring on the fullerene cage might be not the optimal compounds for realization of the through-space electronic interactions between organic addends and the fullerene cage.…”

“…[97] We succeeded in the preparation of 1',2',5'-trisubstituted pyrrolidinofullerenes bearing two aryl groups in the pyrrolidine ring (Fig. 19) [132].…”