Electron Transfer at the Single‐Molecule Level in a Triphenylamine–Perylene Imide Molecule

Abstract

Photoinduced electron transfer (ET) processes in a donor-acceptor system based on triphenylamine and perylene imide have been studied at the single-molecule (SM) and ensemble levels. The system exists as two isomers, one of which undergoes forward and reverse ET in toluene with decay constants of 3.0 and 2.2x10(9) s(-1), respectively, resulting in the dual emission of quenched and delayed fluorescence while the other isomer remains ET-inactive. The fluorescence of both isomers is heavily quenched in the more polar solvent, diethyl ether, by ET. A broad range of ET dynamics is seen at the SM level in polystryene with the two isomers nonresolvable indicating that the local nanoenvironment of the SMs varies considerably throughout the polymer matrix. Both the electronic coupling and the driving force for ET are shown to influence the ET dynamics. Many fluorescence trajectories of SMs show long periods (tens of milliseconds to seconds) where the count rate is attenuated either partly (a "dim" state) or to the background level (an "off-time"). During these periods, the reduction or interruption of emission is attributed to cycles of rapid charge separation followed by charge recombination to the ground state reducing the fluorescence quantum yield of the SM.

The Rylene Colorant Family—Tailored Nanoemitters for Photonics Research and Applications

“…As a net result, the emitted fluorescence is delayed but can retain a high quantum yield. [162][163][164] Figure 14. Top: Chemical structure of the triad 31 containing eight NMI chromophores in the outer shell, four PMI chromophores within the scaffold, and one TDI in the center.…”

Charge Transfer in Single Chains of a Donor–Acceptor Conjugated Tri-Block Copolymer

“…Delayed fluorescence arising from an LE−CT equilibrium is relatively unusual and has been reported at the single-molecule level in only a few cases. 15,40 To our knowledge, this is the first example of delayed fluorescence in single chains of a donor−acceptor conjugated copolymer arising from this mechanism.…”

Comparison of the Photophysical Parameters for Three Perylene Bisimide Derivatives by Single‐Molecule Spectroscopy

“…[32] Here we exploit single-molecule spectroscopy to compare the photophysical properties of three PBI derivatives, shown schematically in Figure 1 and labeled PBI A, B, and C. They have been chosen for the following reasons: PBI A is one of the best characterized chromophores within the class of tetraphenoxy-bay-substituted perylene bisimides [21,25,[33][34][35][36][37] and PBI C has been applied as a molecular building block in several selfassembled supramolecular architectures. [38] However, recently there is increasing evidence from spectroscopic studies of these and related tetraphenoxy-substituted perylene bisimides that these dyes can exist in two conformational states that exhibit quite different emission properties, that is, fluorescence maxima, excited state lifetime and fluorescence quantum yield.…”

“…Hence it is not surprising that these chromophores have played a prominent role in the search for novel functional organic materials in recent years. Indeed highly efficient excitation energy and charge transfer properties have been demonstrated for multichromophoric dendrimers, [20,21] self-organized metallo-supramolecular molecular squares, [22][23][24] and donor-acceptor dyads [25][26][27][28][29] based on these chromophores. The functional properties of such assemblies are determined by the properties of the electronically excited states of the aggregate, which in turn depend crucially on both the geometric arrangement of the subunits with respect to each other and the properties of the electronically excited states of the molecular building blocks.…”