The design of new organic functional molecules able to harvest sun light and efficiently undergo photon to current energy conversion processes is at the forefront of chemical challenges. In this review, the fundamental contribution of chemistry to the multidisciplinary field of organic photovoltaics is presented in a systematic way through the wide variety of organic compounds synthesized to be successfully used in photovoltaic devices.

Since the discovery of C₆₀fullerene, carbon-based nanostructures have become one of the hottest research topics in science. During the past decade research efforts have mainly been devoted to the investigation of C₆₀ and carbon nanotubes, although the ability of carbon to exist in different allotropic forms has provided a variety of nanoscale size shapes with fascinating properties. In this article we highlight some of the most representative examples that document the scientific progress accomplished in this field which, surprisingly, started with a serendipitous discovery.

Plastic solar cells were fabricated using a low-band-gap alternating copolymer of fluorene and a donor–acceptor–donor moiety (APFO-Green1), blended with [6,6]-phenyl-${\mathrm{C}}_{61}$ -butyric acid methylester or $3^{\prime }$ -(3,5-Bis-trifluoromethylphenyl)-$1^{\prime }$ -(4-nitrophenyl)pyrazolino[60]fullerene as electron acceptors. The polymer shows optical absorption in two wavelength ranges from $300<\lambda <500\mathrm{nm}$ and $650<\lambda <1000\mathrm{nm}$ . Devices based on APFO-Green1 blended with the later fullerene exhibit an outstanding photovoltaic behavior at the infrared range, where the external quantum efficiency is as high as 8.4% at $840\mathrm{nm}$ and 7% at $900\mathrm{nm}$ , while the onset of photogeneration is found at $1\mu \mathrm{m}$ . A photocurrent density of $1.76\mathrm{mA}∕{\mathrm{cm}}^2$ , open-circuit voltage of $0.54\mathrm{V}$ , and power conversion efficiency of 0.3% are achieved under the illumination of AM1.5 $(1000\mathrm{W}∕{\mathrm{m}}^2)$ from a solar simulator.