Diketopyrrolopyrrole

Diketopyrrolopyrrole (DPP) is a heterocyclic organic compound that serves as a common building block in dyes and organic semiconductors. The core consists of two five‑membered lactam rings fused to a central conjugated framework, producing a rigid, planar, highly conjugated system. The central diketone functionality makes the core electron-deficient, enabling strong absorption and allowing electronic properties to be tuned by substituents on the lactam nitrogens and on attached aryl groups.

DPPs are valued for their intense coloration, high molar extinction coefficients in the visible region, and robust thermal and photochemical stability. Substituents on the lactam nitrogens and on the attached aryl rings influence solubility, aggregation behavior, and frontier orbital energies, which in turn affect performance in electronic devices. The planarity and propensity for π–π stacking in the solid state support efficient charge transport in thin films, a key feature for device applications.

Synthesis of DPP cores typically involves cyclocondensation and subsequent oxidation of suitably substituted succinimide derivatives, with various N-substituents introduced to improve solubility and processability. The resulting DPP derivatives are versatile platforms for constructing conjugated polymers and small molecules. A wide range of substituents allows tuning of optical bandgap, absorption range, and energy levels to suit specific applications.

Applications of DPPs span organic electronics and dyes. In solar cells and organic field-effect transistors, DPP units often act as strong electron acceptors or ambipolar components in donor–acceptor architectures. They are also used as pigments and dyes in coatings and printing, and as building blocks in conjugated polymers that exhibit notable visible to near-infrared absorption.