Studies on switching of J and H aggregates in Donor-Acceptor molecular materials
Abstract
The aggregation of molecular materials plays a central role in determining their functional
properties. In the aggregated state, conjugated chromophores may exhibit enhanced
emission, in comparison to their dilute solution. The studies described in this thesis is
aimed towards understanding the dynamic behaviour of aggregates (H and J type) in
donor-acceptor based -conjugated chromophores. We discuss the synthesis and characterization
of three diketopyrrolopyrrole (DPP) based chromophores and their optical
properties in solution and thin fi lm. The H and J type aggregates were identi fied by
temperature dependence photoluminescence studies. The observation of both H and J aggregates
in thin fi lms (pure and with host) of one of the DPP derivatives are corroborated
by computational investigations of coulombic coupling between the monomers. By varying
the shearing angle between the monomers in the crystal geometry, we nd that both the
type of aggregates can exist, in line with the different temperature-dependent intensity
ratio plots.