A Paradigmatic Change: Linking Fullerenes to Electron Acceptors

The potential of Lu3N@C-80 and its analogues as electron acceptors in the areas of photovoltaics and artificial photosynthesis is tremendous. To this date, their electron-donating properties have never been explored, despite the facile oxidations that they reveal when compared to those of C. Herein, we report on the synthesis and physicochemical studies of a covalently linked Lu3N@C-80-perylenebisimide (PDI) conjugate, in which PDI acts as the light harvester and the electron acceptor. Most important is the unambiguous evidence-in terms of spectroscopy and kinetics-that corroborates a photoinduced electron transfer evolving from the ground state of Lu3N@C-80 to the singlet excited state of PDI. In stark contrast, the photoreactivity of a C-60-PDI conjugate is exclusively governed by a cascade of energy-transfer processes. Also, the electron-donating property of the Lu3N@C-80 moiety was confirmed through constructing and testing a bilayer heterojunction solar cell device with a PDI and Lu3N@C-80 derivative as electron acceptor and electron donor, respectively. In particular, a positive phcitovoltage of 046 V and a negative short circuit current density of 0.38 mA are observed with PDI/Ca as anode and ITO/Lu3N@C-80 as cathode. Although the devices were not optimized, the sign of the V-OC and the flow direction of J(SC) Clearly underline the unique oxidative role of Lu3N@C-80 within electron donor-acceptor conjugates toward the construction of novel optoelectronic devices.