Red Emitting N-Functionalized Poly(1,4-diketo-3,6-diphenylpyrrolo[3,4-c]pyrrole) (Poly-DPP):  A Deeply Colored Polymer with Unusually Large Stokes Shift

Abstract

New π-conjugated polymers are described, which entirely consist of aryl-aryl-coupled 1,4-diketo-2,5-dialkyl-3,6-diphenylpyrrolo[3,4-c]pyrrole (DPP) units. The alkyl groups are n-hexyl (4a) or 2-ethylhexyl (4b) groups. The polymers are synthesized using nickel-promoted and palladium-catalyzed one-pot coupling reactions starting from 1,4-diketo-2,5-dialkyl-3,6-di(4-bromophenyl)pyrrolo[3,4-c]pyrrole (dibromo-DPP) as monomer, or conventional palladium-catalyzed coupling of dibromo-DPP and the 3,6-bis(pinacolato)boronester derivative of DPP. Polymers exhibit molecular weights up to 33 000 and are excellently soluble in chloroform and toluene. Deep red solutions (λ max of 4b: 525 nm) with intense red photoemission (λ max of 4b: 632 nm) and unusually large Stokes shift up to 107 nm are obtained. Cyclic voltammetry indicates quasi-reversible oxidation and reduction behavior, the onset potentials of 4b are +1.03 and -0.74 V vs SCE, respectively. From these potentials, HOMO/ LUMO levels of -5.47 and -3.70 eV, respectively, can be calculated. Good solubility and processability into thin films render the compounds suitable for electronic applications.

Efficient red electroluminescence from diketopyrrolopyrrole copolymerised with a polyfluorene

“…[39][40][41][42][43][44][45][46] Their use as solid-state emitters has, however, been limited by quenching of the emission by a strong propensity towards aggregation of molecules caused by π -π interactions and hydrogen bonding. 47 Consequently, there are very few examples of the development of DPP-only polymers for luminescence, 48 with copolymerization of DPP with wide gap host materials [39][40][41][42][43][44][45][46] being the preferred approach to obtain efficient emissive materials for use in PLEDs. Despite much effort, this relatively successful copolymerization approach still only yields external electroluminescence quantum efficiencies (EQE) of no more than 0.7% (Ref.…”

Recent Advances in P-Type Conjugated Polymers for High-Performance Solar Cells

“…Due to its rigid planar structure, and strong intermolecular interaction, DPP unit without proper aliphatic side chains as solubilizing groups is highly crystalline, and thus insoluble in common solvents incorporation of N-alkylated 1,4-diketo-3,6-diphenylpyrrolo [3,4-c]pyrrole (DPPPh 2 ) unit into conjugated polymer backbones was first reported for the materials used in the nonlinear optical (NLO) and polymer light emitting diode (PLED) applications. The electron-deficient nature of the DPP unit bathochromically shifts the absorption and emission spectra of the resulting conjugated molecules to allow efficient sensitizing at wavelengths around 400-550 nm or to achieve a deep red emitter [56][57][58][59]. However, the homopolymer of DPP-Ph 2 (P10, (P11) covers from 600-1,000 nm, which is favorable in solar radiation harvesting.…”

Diketopyrrolopyrrole-based chemosensors for selective recognition of fluoride ions

“…11 Diketopyrrolopyrrole (DPP) pigments were discovered in the 1980s and were mainly used as low-cost pigments for application with high-quality demands. [12][13] DPPs were also applied in biophotonics and optoelectronics 14 for preparation of low bandgap conjugated polymers [15][16][17][18] or copolymers used in semiconductors. 19 Recently, many research groups reported progress in the development of DPP-containing fluorescent sensors, and they investigated their applications in selective detection of thiols, Zn 2+ , cyanide, pH, DNA and CO 2 .…”