Meeting the challenge of designing new light-emitting materials, we synthesized the compound N-isopropylcarbazole (CBL)−SiMe 2 −divinylbenzene (DVB), which represents the general idea of building attractive emitters by stitching together simple, well-known block elements. Following this strategy, an extraordinary emission emerges from photoinduced intramolecular processes between silylene-bridged adjacent chromophores, e.g., intramolecular energy and/or electron transfer (PET). The reported compound displays an attractive blue emission that occurs no matter which of the linked chromophores is excited (i.e., regardless of the excitation wavelength in the range 240−360 nm). Excitation of CBL leads directly to intramolecular charge transfer (ICT) state formation within 35 ps, whereas excitation of DVB results in "pumping" the CBL excited state via 300 fs energy transfer. In the latter case, DVB acts as an intramolecular photosensitizer of the ICT precursor. Both mechanisms, proceeding via ultrafast processes, are confirmed by femtosecond transient absorption experiments performed on the investigated bichromophoric compound and its individual Si-containing chromophores in acetonitrile solution. Analysis of the transient absorption bands allowed us to characterize the ICT excited state as a radical ion pair of carbazole radical cation and divinylbenzene radical anion linked by a silylene bridge.

Styrylcarbazole linked to pyrene by a dimethylsilyl bridge was synthesized in the search for new charge-transfer active materials for LED applications. In the course of a photophysical study, it turned out that such a donor-bridge-acceptor compound displayed three completely different types of emission depending on solvent polarity. The most attractive emission properties were found in acetonitrile in which two broad emission bands were observed. The resolved mechanism of the excited-state processes in acetonitrile was supported by singular value decomposition with self-modeling treatment of time-resolved emission spectra (ns-TCSPC). The data analysis revealed that there were two excited-state processes, that is, charge transfer within styrylcarbazole and electron transfer from styrylcarbazole to pyrene through a silylene bridge that was responsible for a broad dual emission. The general idea of designing compounds that display emission from more than one excited state covering a wide range of the visible spectrum can be a powerful tool in designing new white-light-emitting materials.

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Enhanced emission of 4,4′-bis(vinyldimethylsilyl)-biphenyl as compared to its carbon analogue resulted from the presence of the silicon atom that caused stronger transition moment of the emissive state and more efficient mixing of the excited states.