Proceedings of 6th International Conference on Hybrid and Organic Photovoltaics (HOPV14)
Publication date: 1st March 2014
We have synthesized and fully characterized an oligothiophene small organic molecule, for its use as electron donor moiety in solution processed bulk-heterojunction organic solar cells. Our results show that device solvent annealing process of the conjugated oligothiophene molecule leads to a light-to-energy conversion efficiency of 3.75% under standard illumination conditions. The solar cell presents open-circuit voltage and fill factors as high as 1.01V and 63.05% respectively, which are among the highest values obtained for small molecule solution processed organic solar cells. Laser Transient Absorption Spectroscopic (L-TAS) as well as fluorescence emission measurements studies, shows a clear correlation between polaron yield, device photocurrent and thin film solvent-annealing time. Moreover, charge extraction (CE) and transient photovoltage (TPV) measurements were carried out in order to determine the charge transfer dynamics in complete devices to determine the main loss mechanisms that govern the overall cell performance under illumination standard conditions and understand the origin of this high Voc.