Organic Photovoltaic (OPV) cells are one of the most promising energy conversion materials of our modern world due to their high-mechanical flexibility, robustness, and low-cost production. However, a crucial drawback remains: their low energy conversion efficiency. A reason for this can be ascribed to electronic-vibrational dynamics affecting the ultrafast charge separation occurring in the material upon light absorption. Substantial efforts have been made to defeat this problem, however the incomplete understanding of the elementary mechanism governing the conversion process has restrained further advancements in this direction. In REPAMPS (Recursive Engineering electronic Properties of Artificial energy Materials with multi-Pulse Spectroscopy). I will deliver a first-principles theoretical description of the charge transfer mechanism governing the energy conversion for a prototypical OPV, the P3HT-PCBM blend, and introduce the novel Spectrally Engineered Control (SEC) methodology to direct the charge transfer process towards higher power conversion. A TDDFT methodology will be used to parametrize the P3HT-PCBM heterojunction in its environment, and a molecular dynamics protocol will be adopted for a realistic modelling of the dissipation and spectral bath. Quantum dynamics with explicit description of the external fields and calculation of various time-resolved optical spectroscopies will be simulated. The signals will be validated in collaboration with an experimental group. Nonadiabatic dynamical processes (e.g. conical intersections) affecting the charge transfer and the environment role will be carefully investigated. Last, I introduce the SEC approach combining optimal control theory with the analysis of the spectra, representing a solid strategy for the photocontrol of the molecular mechanism (charge-transfer) governing the power conversion in OPV materials. I will then propose new design strategies for OPV materials using the insights gained from REPAMPS.
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