The Synthesis and Photophysical Properties of Weakly Coupled Diketopyrrolopyrroles

Abstract

Three centrosymmetric diketopyrrolopyrroles possessing either two 2-(2′-methoxyphenyl)benzothiazole or two 2-(2′-methoxyphenyl)benzoxazolo-thiophene scaffolds were synthesized in a straightforward manner, and their photophysical properties were investigated. Their emission was significantly bathochromically shifted as compared with that of simple DPPs reaching 650 nm. Judging from theoretical calculations performed with time-dependent density functional theory, in all three cases the excited state was localized on the DPP core and there was no significant CT character. Consequently, emission was almost independent of solvents’ polarity. DPPs possessing 2,5-thiophene units vicinal to DPP core play a role in electronic transitions, resulting in bathochromically shifted absorption and emission. Interestingly, as judged from transient absorption dynamics, intersystem crossing was responsible for the deactivation of the excited states of DPPs possessing para linkers but not in the case of dye bearing meta linker.

Photophysics of Benzoxazole and Dicyano Functionalised Diketopyrrolopyrrole Derivatives: Insights into Ultrafast Processes and the Triplet State

“…[41] Due to the symmetric molecular structure, we do not expect a strong polarity dependence and thus the role of solvation should be negligible. [27,42] It is clear from the absorption spectra (Figure 2B) and the choice of pump wavelength (625 nm) that an excess of vibrational energy is supplied during excitation. Since it is well known that vibrational process occurs within the ps timescale, it is reasonable to assume that vibronic processes should be responsible for the spectral evolution.…”

Photophysics of Benzoxazole and Dicyano Functionalised Diketopyrrolopyrrole Derivatives: Insights into Ultrafast Processes and the Triplet State

“…[39] Due to the symmetric molecular structure, we do not expect a strong polarity dependence and thus the role of solvation should be negligible. [27,40] It is clear from the absorption spectra (Figure 2B) and the choice of pump wavelength (625 nm) that an excess of vibrational energy is supplied during excitation. Since it is well known that vibrational process occurs within the ps timescale, it is reasonable to assume that vibronic processes should be responsible for the spectral evolution.…”

Vinylene-linked diketopyrrolopyrrole chromophores for electrochromism

“…These attributes include robust visible light absorption and emission, exceptional fluorescence quantum yields, intense colouration, and remarkable charge mobility. 1–8 Furthermore, DPP exhibits excellent thermal and photostability and can be readily functionalized, making it a versatile platform for developing various DPP-based small molecules and polymers for a wide array of applications such as organic solar cells, organic field-effect transistors (OFETs), and sensors. 9–16…”

“…These attributes include robust visible light absorption and emission, exceptional uorescence quantum yields, intense colouration, and remarkable charge mobility. [1][2][3][4][5][6][7][8] Furthermore, DPP exhibits excellent thermal and photostability and can be readily functionalized, making it a versatile platform for developing various DPP-based small molecules and polymers for a wide array of applications such as organic solar cells, organic eld-effect transistors (OFETs), and sensors. [9][10][11][12][13][14][15][16] Given the popularity of DPP systems, diverse synthetic approaches have been devised to ne-tune the p-structure and properties of DPP, leveraging groups like -NH, -C]O, and aromatic units.…”