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New [60] and [70]fullerene homo-and heterodimers absorbing in the visible region have been synthesized and fully characterized. In order to increase the solubility and processability of the new fullerene dimers, different alkyl chains have been used which has allowed the determination of the influence of the solubilizing alkyl groups on the photovoltaic performance. Atomic force microscopy experiments carried out on blends of these dimers and P3HT evidenced the formation of large aggregates, which significantly influence the photovoltaic efficiency.

A series of novel polymers (P1P6) derived from the combination of different units (including thiophene, triarylamine, and spirobifluorene) were successfully synthesized, completely characterized, and used as hole-transporting materials (HTMs) for perovskite solar cells (PSCs). Solar cells with some of these materials as HTMs showed very good performances of almost 13% (12.75% for P4 and 12.38% for P6) even without additives, and devices based on these new HTMs show relatively improved stability against temperature compared to those based on PTAA. The presence of dopant additives has been linked to long-term degradation, which is the main barrier to the large-scale commercialization of this innovative type of solar cell. Obtaining efficient PSCs without using dopants could represent a further step toward improvement of long-term stability and thus their introduction into the market.

The development of new light harvesting materials is a key issue for the progress of the research on organic & hybrid photovoltaics. Here, we report a new class of organic sensitizers based on the bi-fluorenylidene moiety as p-linker within the donor–p-linker–acceptor (D–p–A) scheme. The new dyes are endowed with electron donor and electron acceptor units at strategic positions in order to improve their electronic and light-harvesting properties. The comprehensive study of these compounds through the use of different experimental and theoretical techniques, provides an in-depth understanding of their electronic and photophysical properties, and reveal their interest as photovoltaic materials.

A cobalt-catalyzed cyclotrimerization of bis(aryl)alkyne is used as an innovative tool to obtain hole-transport materials (HTMs). The novel HTM containing six units of oligotriarylamine (HAB1), characterized by UV-vis, cyclic voltammetry, DFT, and thermogravimetric analysis, confirms its suitability as an efficient HTM in PSCs. A PCE of 17.5% was obtained in HAB1-containing PSCs, a performance comparable to that obtained with spiro-OMeTAD and with slightly better thermal stability.