Fullerenes and porphyrins are molecular architectures ideally suited for devising integrated, multicomponent model systems to transmit and process solar energy. Implementation of C₆₀ as a 3-dimensional electron acceptor holds great expectations on account of their small reorganization energy in electron transfer reactions and has exerted a noteworthy impact on the improvement of light-induced charge-separation. This article describes how the specific compositions of porphyrin chromophores linked to C₆₀—yielding artificial light harvesting antenna and reaction center mimics—have been elegantly utilized to tune the electronic couplings between donor and acceptor sites and the total reorganization energy. Specifically, the effects that these parameters have on the rate, yield and lifetime of the energetic charge-separated states are considered.

This feature article highlights the advantages of employing [60]fullerene as a viable electron accepting building block in novel donor acceptor systems. Different strategies that aim towards improving charge separation in fullerene containing systems are presented. This is accomplished, for example, via utilisation of additional stabilisation forces of the radical pair or, alternatively, diffusional splitting of the last mentioned. Fine-tuning the topology of the electron donor moiety has been shown to be a powerful means of influencing the relative energies of the two states involved (e.g. the charge-separated state vs. the singlet ground state). Remarkable effects concerning the lifetime of the charge-separated radical pair were observed, in particular, in systems that upon charge separation led to a gain of aromaticity and planarity of the oxidised fragment.

This tutorial review surveys recent advances in the field of C₆₀/π-conjugated oligomer donor–acceptor ensembles. In particular, different synthetic strategies are discussed that were developed to link π-conjugated oligomers, as versatile photoexcited state electron donors, to C₆₀. We highlight relationships between the nature/structural aspects of π-conjugated donor systems and a variety of physico-chemical features. Modifications of the oligomeric components are discussed under aspects of tailoring (i) the absorption cross-section of the chromophore in the visible region, (ii) the oxidation potential of the oligomeric donor moiety, (iii) the size, shape, or chemical makeup of the oligomer, and (iv) the stabilization of the charge-separated radical ion pairs. In the final section, the applicability of selected materials for the fabrication of photovoltaic devices is analyzed.

Significance: In the present work, we show compelling evidence for the unprecedented intramolecular singlet fission at room temperature and in dilute solutions within a set of three different regioisomeric pentacene dimers. Pump–probe experiments, which were complemented by theoretical calculations using high-level ab initio multireference perturbation theory methods, corroborate triplet quantum yields as high as 156 ± 5%. To this end, electronic couplings between the two pentacenes in the dimers, by virtue of through-bond or through-space interactions, are decisive in tuning the rates of singlet fission.

This tutorial review surveys and highlights the integration of different molecular wires—in combination with chromophores that exhibit (i) significant absorption cross section throughout the visible part of the solar spectrum and (ii) good electron donating power—into novel electron donor–acceptor conjugates. The focus is predominantly on charge transfer and charge transport features of the most promising systems.