Photovoltaics (PV) is a major actor of the ongoing energy transition towards a low- carbon- emission society. More than 1.6 TW of PV systems were operational at the beginning of the year 2024, producing more than 2135 TWh of electricity, or 8.3% of the global electricity demand. Several factors lie behind the plummeting cost and fast ramp up of this technology. One factor is the fact that PV is modular: Identical solar panels of hundreds of watts are combined, by the dozens in rooftop installations, or by the millions in utility-scale power plants. Another successful factor relies on the possibility to adapt PV devices to different requirements realizing for example high-power modules, semitransparent PV modules, flexible products, etc..

Several semiconductor materials, realized with different processes, have been used as absorber of solar cells: today more than 98% of the overall cell production is made with crystalline silicon, while the remaining part of the production is obtained with inorganic thin film materials (manly CdTe, CIGS, and CIS). Organic and hybrid materials can contribute to the realization of the next generation of photovoltaic modules with improved performance or which can be used to integrate photovoltaics in various contexts such as the building-integrated PV or the agrivoltaics.

In this presentation an overview of the work done on the development of innovative materials and solar cells in Solar Photovoltaic Division of ENEA is reported.

Starting from our expertise on silicon-based solar cells, the research on hybride halide perovskite solar cells for the development of perovskite/silicon tandem devices will be discussed. As for the bottom cell, heterojunction silicon solar cells (SHJ) realized on both p-type and n-type silicon wafers have been considered, studying also selective contacts alternative to the doped silicon thin films generally used in the current SHJ device architectures. n-i-p or p-i-n perovskite solar cells have been used for the top component, studying different carrier transporting layers and developing appropriate transparent front electrodes for perovskite/Si tandem cell.

On the other hand, the research on semitransparent spectrally-selective thin film PV will be discussed as a promising approach for agrivoltaic application and in particular for PV greenhouses with reduced energy demand. The approach aims at an integrated complementary use of solar light for PV and photosynthesis, by tuning the transmission of the PV modules on the absorption spectrum of the plants. We studied two possible implementations, one based on organic PV and one on thin film silicon PV. In particular, the organic approach will be presented, where spectral selectivity can be achieved by tailoring the absorption characteristics of the active materials.