Facile Synthesis and Chain‐Length Dependence of the Optical and Structural Properties of Diketopyrrolopyrrole‐Based Oligomers

Abstract

Here, we report the synthesis, optical properties, and solid-state packing of monodisperse oligomers of diketopyrrolopyrrole (DPP) up to five repeating units. The optical properties of DPP oligomers in solution and the solid state were investigated by a combination of steady-state and transient spectroscopy. Transient absorption spectroscopy and time-correlated single photon counting (TCSPC) measurements show that the fluorescence lifetime decreases with an increase in the oligomer size from monomer to trimer, thereby reaching saturation for pentameric DPP oligomers. The solid-state packing and crystallinity were probed by using advanced techniques, which included grazing incidence small-angle X-ray scattering (GISAXS) and X-ray diffraction (XRD) to elucidate the structure-property trend. Collectively, our chain-length dependent studies establish the fundamental correlation between the structure and property and provide a comprehensive understanding of the solid-state properties in DPP-DPP based conjugated systems.

Photophysical and Optical Properties of Semiconducting Polymer Nanoparticles Prepared from Hyaluronic Acid and Polysorbate 80

“…The decay of the excited-state absorptions and the recovery of the ground-state bleach show nearly identical kinetics, and the absence of new transient signals or the presence of a rise time indicate that no intermediate excited-state species are formed after photoexcitation. The lack of these features and the short excited-state lifetime further suggests a tightly bound electron–hole pair, which rapidly recombines, which is supported by the short conjugation length (approximately three units) that has been reported for a similar structure …”

“…As previously observed for similar conjugated polymer systems, P­(DPP-T) , P­(DPP-2T) , and P­(DPP-3T) were found to be nonluminescent in THF solution . Therefore, because of this lack of emission, TA spectroscopy in THF was required to determine the excited-state lifetimes and kinetics of the polymers before and after nanoprecipitation.…”

“…As previously observed for similar conjugated polymer systems, P(DPP-T) , P(DPP-2T) , and P(DPP-3T) were found to be nonluminescent in THF solution. 52 Therefore, because of this lack of emission, TA spectroscopy in THF was required to determine the excited-state lifetimes and kinetics of the polymers before and after nanoprecipitation. As detailed in the Supporting Information, the samples were excited with the fundamental output of the Ti-sapphire laser at 795 nm and were probed using a white light continuum generated by passing the 795 nm pulse through a sapphire window.…”

“…The lack of these features and the short excited-state lifetime further suggests a tightly bound electron–hole pair, which rapidly recombines, which is supported by the short conjugation length (approximately three units) that has been reported for a similar structure. 52…”

Tuning the Formation of J and H Aggregates in Diketopyrrolopyrrole Materials

“…1) by performing concentration, temperature and computational studies, and report on the possibility of tuning the type of aggregate formed using concentration and temperature handles. DPP derivatives have been extensively studied by some of the authors 17 and interesting structure-property correlations have been found in terms of dependence of fluorescence lifetimes on the chain-length of these derivatives. Unlike previous works, the steady state absorption and photoluminescence (PL) spectra for the current DPP derivative show pronounced tails suggestive of presence of one or more type of aggregates.…”