Photovoltaics (PV) is a major actor of the ongoing energy transition towards a low- carbon- emission society. Annual PV installations in 2024 reached the remarkable value of 601 GW (up from 465 GW in 2023), bringing the cumulative global PV capacity to over 2.2 TW at the beginning of 2025. This cumulative capacity should be able to supply at least 10% of the world’s electricity consumption in 2025, generating more than an expected 2950 TWh, avoiding just over 1000 Mt of CO2 emissions, equivalent to 2.8% of all energy-related emissions. Several factors lie behind the plummeting cost and fast ramp up of the PV 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). Innovative 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 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 hybrid and inorganic perovskites deposited with different approaches (solution processes, co-evaporation, two-step, hybrid evaporation/spin-coating method), different carrier transporting layers and developing appropriate transparent front electrodes for perovskite/Si tandem cell.