Leta i Linköpings universitets forskning

På LiU E-Press har vi registrerat de flesta publikationer från LiU. Skriv några nyckelord, välj publikationstyp...

On the Dissociation Efficiency of Charge Transfer Excitons and Frenkel Excitons in Organic Solar Cells: A Luminescence Quenching Study
Article in journal
Kristofer Tvingstedt, Koen Vandewal, Fengling Zhang, Olle Inganäs
Publication Year
The Journal of Physical Chemistry C, 2010, (114)49, 21824-21832
Link to Source (DOI)
<p>The field dependence of photocurrent found in many organic solar cells is a significant and detrimental setback for internal quantum efficiency. In this work we study the important contribution to this field dependence due to the dissociation efficiency of the weakly bound interfacial charge transfer (CT) state, crucial for organic bulk heterojunction solar cells. Three different donor polymers and two different acceptors are examined, and their respective dissociation characteristics are evaluated by photoluminescence (PL) quenching, both for Frenkel excitons and for the intermolecular charge transfer excitons. We observe that while the field-dependent photocurrent for pure polymers does correlate well with quenching efficiency, the CT exciton quenching from the blend generally displays a less pronounced correlation with extracted photocurrent. We further note that while the electroluminescence and photoluminescence of the pure polymer are identical, we observe a red shift for the blend electroluminescence. This indicates that lower energetic states, not visible in PL, are available in the blend. The emissive state of the blends probed by PL is therefore proposed to originate from sites that are involved in photocurrent generation to a lesser extent.</p>