Organic mixed valence systems (MV) are molecules containing two or more redox centers lin ed by a π-conjugated system, the poly-arylamine MV being the most used. Their structures and electronic properties make them efficient materials for the use as hole transport materials (HTM) in dye-sensitized solar cells (DSSC), OLED and perovskite-based solar cells (PSC).[1, 2, 3] This work focuses on the investigation, both in liquid and solid state, of the photophysics of the excited triplet states and on the intramolecular charge transfer in the radical cations of several newly developed arylamine MV. The paramagnetic nature of both triplet states and radical cations makes EPR spectroscopy a particularly useful technique to carry out their characterization. In particular, Time-resolved EPR spectroscopy is employed to investigate the photophysics of the excited triplet states and rationalize their population and depopulation …