The significance of fullerene electron acceptors in organic solar cell photo-oxidation

Abstract

Stability of organic solar cells requires development before their commercialisation is possible. This review will give a brief overview of organic solar cells and their stability, before focussing on the photochemical stability of the active layer. The photo-oxidation of the donor polymers will be looked at first which has been studied quite extensively and then fullerene electron acceptors, such as widely used phenyl-C61-butyric acid methyl ester, which has been considerably less studied. It has been shown that oxidation of the fullerene cage on phenyl-C61-butyric acid methyl ester results in oxides with a deeper lowest unoccupied molecular orbital (LUMO) level than the fresh electron acceptor. These oxides act as electron traps, leading to deterioration of the blend photoconductivity. The significance of fullerene photo-oxidation on device stability has been indirectly shown via research on: photoconductivity; organic solar cells made with an oxidised fullerene derivative and organic field effect transistors. Techniques that could be developed to increase photochemical stability of fullerene electron acceptor resistance to photooxidation include: reducing its LUMO level; increasing its crystallinity or aggregation and changing its chemical structure. Improving the photochemical stability of organic solar cells would move us one step closer to a more accessible solar power.

Fullerene-Tetrabenzofluorene (C60-TBF) in Multivalent Photosensitisation for Enhanced ZnO-based Photo-catalysts: Mono vs. Hexakis Adduct

“…In this context, fullerene has been emerged as the material of choice as an electron acceptor due to its high electron mobility, excellent thermal stability, and outstanding charge transport characteristics with a bandgap of ~1.6-1.9 eV, hence has been used frequently in photovoltaic device 10,11 and other energy transfer devices. 12 Recently, the influences of fullerene on photo-catalytic performance have been studied. [13][14][15] Hongbo et al reported that the fullerene hybridized zinc oxide surface enhances the degree of photocatalytic activity; fullerene not only helps to obtain higher efficiency and also provides photostability to the ZnO surface.…”

Doubly-Charged Negative Ions as Novel Tunable Catalysts: Graphene and Fullerene Molecules Versus Atomic Metals

“…The advent of the COVID-19 pandemic has also accelerated a vigorous search for and synthesis of atomic nanoparticles and catalysts for various applications (see for examples [17,18]). The stability of organic solar cells that is required before their actual commercialization is of particular interest here [19]. The use of fullerenes with large electron affinities (EAs) is part of the recommended solution [19].…”

“…The stability of organic solar cells that is required before their actual commercialization is of particular interest here [19]. The use of fullerenes with large electron affinities (EAs) is part of the recommended solution [19]. The formation of high-energy singlet oxygen and super oxygen radical anions, contributing to the degradation mechanism of the employed polymers, could be mitigated through the use of appropriate tunable catalysts, presented in this paper.…”

Doubly-charged Negative Ions as Novel Tunable Catalysts: Graphene and Fullerene Molecules Versus Atomic Metals

“…The advent of the COVID-19 pandemic has also accelerated the vigorous search for and synthesis of atomic nanoparticles and catalysts for various applications, see for examples [17,18]. Of particular interest here is also the stability of organic solar cells required before their actual commercialization [19]. The use of fullerenes with large electron affinities (EAs) is part of the recommended solution [19].…”

“…Of particular interest here is also the stability of organic solar cells required before their actual commercialization [19]. The use of fullerenes with large electron affinities (EAs) is part of the recommended solution [19]. The formation of the high energy singlet oxygen and the super oxygen radical anions, contributing to the degradation mechanism of the employed polymers, could be mitigated through the use of appropriate tunable catalysts presented in this paper.…”