Following the homodoping strategy, which consists of mixing two amphiphilic derivatives of the same electroactive compound, one in the neutral state whereas the other is ionic, we have carefully investigated the mixed monolayers by in situ experiments. Using surface pressure isotherms together with surface potential technique but also visible-UV and IR spectroscopies we have characterized the molecular organization. We have shown for the first time that for a given range of mixtures mixed valence clusters likely to be TCNQ-type dimers are formed at the air-water interface.