INtegrated Theoretical and Experimental Study for the development of new generAtion excitonic SOLar cElls

The development of cost-efficient solar cells is one of the most important challenges to increase energy production from renewable sources and to fight climate change, two task of outstanding importance, as recognized by the mission M2C2 of the PNRR and in COP26 conference. Organic (OSC) and perovskite (PSC) solar cells are potentially well suited for large-scale commercialization, because of their low-cost, lower sensitivity to environmental conditions, and good performance in low-light conditions, being suitable for sustainable small- and large-scale electronic devices, and energetically self-sufficient buildings. Unfortunately, in OSCs, voltage losses due to non-radiative recombination are much higher than in conventional inorganic solar cells and this greatly hampers their commercialization. Therefore, one of the primary objectives of this research project is the understanding and possibly the removal of non-radiative decay paths in OSCs, a task successfully applied in the past to GaAs solar cells. Herein, with this goal in mind, we plan to integrate theoretical and experimental studies for achieving a comprehensive understanding of the most common decay paths in OSCs, leading to a rational design of new materials with enhanced efficiencies. The integration of different expertise will enable paying the same attention to different facets of the problem: the morphology of the relevant interfaces, their electronic structure at an atomistic level, and the computation of the rates of the elementary processes involved, e.g. charge separation, charge recombination, triplet formation. The latter point is a relevant novelty, which has been largely overlooked in the current literature, mostly focused on energy level alignment rather than rate constant ratios. The impact of triplet formation on the performances is also proved by its inclusion among the main topics of the Samsung Ltd. financing GRO schemes, a fact that points out the commercial impact of the study we propose. As a second significant target, we plan to the synthesize novel non-fullerene acceptors (NFA), characterized by a significant absorption in the NIR zone of the optical spectrum. The new compounds will be tested in devices fabricated using commercial polymeric materials as donor materials, featuring complementary absorption spectrum in order to exploit the whole solar bandwidth in OSC. Theoretical predictions of the efficiency of these materials will be corroborated by experimental fabrication and characterization of the devices. Finally, a PSC exploiting crystals of a photoactive protein as active containers for perovskite will be developed by microfluidic approaches. Such PSC could be fitted in flexible cells because crystals will be supported by Lipidic Cubic Phase and could provide a green alternative to traditional photosensitizer. Perovskite/protein structure and energy transfer mechanisms between these components of PSC will be analyzed by structural and theoretical studies.