Tuning the Formation of J and H Aggregates in Diketopyrrolopyrrole Materials

The aggregation of molecules in devices plays a central role in determining their functional

properties. In the aggregated state, pi conjugated chromophores can exhibit enhanced emission

in comparison to their dilute solution. Here we synthesize and characterize a diketopyrrolopyrrole

(DPP) based donor-acceptor molecule in terms of its optical properties in

solution and thin film. Temperature and concentration dependent photoluminescence studies

reveal the presence of both H and J aggregates in thin film, which is corroborated by

computational investigations of the coulombic coupling in the crystal structure of the DPP

derivative. We find that the type of aggregate formed is extremely sensitive to the variation

in the shearing angle between the monomers in the crystal structure geometry.

Abstract