Well‐Defined and Monodisperse Linear and Star‐Shaped Quaterfluorene‐DPP Molecules: the Significance of Conjugation and Dimensionality

Abstract

The synthesis of three new 1,4‐diketo‐3,6‐diphenyl‐pyrrolo[3,4‐c]pyrrole (DPP) macromolecules appended with two or four quaterfluorene arms is reported. The compounds absorb mainly through the oligofluorene units and emit through the DPP core. Optical gain has been observed for Linear‐c, a two‐armed structure in which the quaterfluorene units are conjugated through the core unit.

Novel electrochemiluminescent materials for sensor applications

“…S1 †). In comparison to other T4 compounds, 20 where there was no uorescence or ECL observed above 450 nm, for T4BT-B there was luminescence observed even above 550 nm, which can be related to the addition of BT units, attributing to longer wavelength emission. However, the ECL monitored is total light produced rather than monitoring a specic wavelength.…”

Natures of optical absorption transitions and excitation energy dependent photostability of diketopyrrolopyrrole (DPP)-based photovoltaic copolymers

“…7 The two absorption bands observed for DPP-based donor-acceptor molecules are well-known and the high and low energy bands have previosuly been assigned to a π-π* transition of the conjugated donor unit and a transition of the DPP unit respectively. 17,25 This model implies a transition between an occupied molecular orbital and an unoccupied one where one or both shows some degree of localisation on part of the molecule, however, published DFT calculations for DPP-copolymers appear to conflict with this understanding suggesting rather that both the frontier molecular orbitals have a similar degree localisation centred on the DPP unit. This behaviour has led to the low energy optical transition being described as an intramolecular charge transfer (ICT) from the donor to the acceptor unit, in line with the model proposed for other donor-acceptor copolymers.…”

“…[1][2][3][4][5][6] Particularly for photovoltaic applications, the low energy gaps of donor-acceptor copolymers are attractive since they can be tuned to optimise harvesting of the solar emission spectrum. 5,10,[14][15][16][17] The high photovoltaic performance of D-A copolymers has been attributed in part to effective charge carrier transport, [18][19][20] but particularly to efficient charge photogeneration related to the charge transfer character of the longest-wavelength electronic transitions. 1,[9][10][11][12][13] One particularly interesting electron-accepting unit is diketopyrrolopyrrole (DPP), which is highly electron-deficient and so can provide very low energy gap materials when combined with an electron rich donor unit such as thiophene or its derivatives.…”

Efficient optical gain media comprising binary blends of poly(3-hexylthiophene) and poly(9,9-dioctylfluorene-co-benzothiadiazole)

“…19,20 We have previously reported on a fluorene-based polymer (Red F, Scheme 1) containing the thiophene-benzothiadiazole-thiophene (TBT) luminophore [21][22][23][24][25] and on molecular glasses with the same luminophore 26 that readily access this wavelength range. Other examples include compounds with a 1,4-diketo-2,3,5,6-tetraphenyl-pyrrolo [3,4-c]pyrrole (DPP) core and 9,9-dialkylfluorene branches 27 and inert polymers with dispersed molecular dyes, for example PMMA/Rhodamine-640 blends. 28,29 Polythiophenes that emit at red wavelengths can be used to make lasers, for example, regiorandom poly(3-hexylthiophene) (RRa-P3HT) and blends with a small fraction of regioregular (RR-) P3HT dispersed in a RRa-P3HT matrix are effective gain media for microring lasers.…”