US EPA

5221792 

Journal Article 

Fluorescence quantum yields of dye aggregates: a showcase example based on self-assembled perylene bisimide dimers 

Fennel, F; Gershberg, J; Stolte, M; Würthner, F 

2018 

1 

Physical Chemistry Chemical Physics
ISSN: 1463-9076
EISSN: 1463-9084 

ROYAL SOC CHEMISTRY 

CAMBRIDGE 

20 

11 

7612-7620 

English 

29493691 

10.1039/c7cp07778e 

WOS:000428235800027 

Constituting an intermediate state of matter between molecules and solid state materials, dye aggregates can give important insights into functional properties. Despite the importance of fluorescence for many applications, it turns out that the conventional methods for quantum yield determination are not applicable to dye aggregates and so far no method has been introduced for the accurate determination of the fluorescence quantum yields of dye aggregates. Here we suggest two measurement routines for the quantum yield determination of strongly absorbing dye aggregates. Both methods provide the quantum yield of the aggregated species without the necessity of reaching a fully aggregated state, which is particularly important for the most common case imparted by the low association constants of π-π-stacking interactions. The routines are experimentally validated with two perylene bisimide dyes whose self-assembly is driven by the concerted interplay of hydrogen bonding and π-π-stacking interactions, leading to structurally well defined co-facially stacked dimers at intermediate concentrations and a further growth into larger H-aggregates at a higher concentration. Compared to other H-aggregates relatively high fluorescence quantum yields of up to 28% are found for both the co-facially stacked dimers and the larger H-aggregates.