A Symmetry‐Broken Charge‐Separated State in the Marcus Inverted Region

Abstract

We report a long‐lived charge‐separated state in a chromophoric pair (DC‐PDI2) that uniquely integrates the advantages of fundamental processes of photosynthetic reaction centers: i) Symmetry‐breaking charge‐separation (SB‐CS) and ii) Marcus‐inverted‐region dependence. The near‐orthogonal bichromophoric DC‐PDI2 manifests an ultrafast evolution of the SB‐CS state with a time constant of τSB-CS ${{\tau }_{{\rm S}{\rm B}-{\rm C}{\rm S}}}$ =0.35±0.02 ps and a slow charge recombination (CR) kinetics with τCR ${{\tau }_{{\rm C}{\rm R}}}$ =4.09±0.01 ns in ACN. The rate constant of CR of DC‐PDI2 is 11 686 times slower than SB‐CS in ACN, as the CR of the PDI radical ion‐pair occurs in the deep inverted region of the Marcus parabola ( -ΔGCR ${{-{\rm \Delta }G}_{{\rm C}{\rm R}}}$ >λ). In contrast, an analogous benzyloxy (BnO)‐substituted DC‐BPDI2 showcases a ≈10‐fold accelerated CR kinetics with τnormalCnormalR/τnormalSnormalB-normalCnormalS ${{\tau }_{{\rm C}{\rm R}}/{\tau }_{{\rm S}{\rm B}-{\rm C}{\rm S}}}$ lowering to ≈1536 in ACN, by virtue of a decreased CR driving force. The present investigation demonstrates a control of molecular engineering to tune the energetics and kinetics of the SB‐CS material, which is essential for next‐generation optoelectronic devices.

Highly Luminescent Chiral Double π-Helical Nanoribbons

“…In comparison with previously reported double π-helices, this series stands out with much higher Φ PL values due to an order of magnitude lower k nr . The exceptional Φ PL values can be attributed to the structural characteristics achieved through the combination of a rigid double π-helical skeleton, diisopropyl phenyl groups instead of flexible alkyl chains, and chlorination at the PDI core. ,, These features collectively underscore an effective strategy for designing high-luminescence chiroptical materials.…”

Efficient Intersystem Crossing and Long‐lived Charge‐Separated State Induced by Through‐Space Intramolecular Charge Transfer in a Parallel Geometry Carbazole‐Bodipy Dyad

“…The long‐lived CS state is desired in photosynthesis and photovoltaic applications [33–35] . Note that the lifetime of the CS state of the BCZ‐1 is nearly 8 times longer than the lifetime formerly observed for perylenebismide dimer with symmetry broken charge transfer state in Marcus‐inverted‐region [36] . This is the first example of such a slow CR process in compact donor‐BDP dyad.…”

“…[33][34][35] Note that the lifetime of the CS state of the BCZ-1 is nearly 8 times longer than the lifetime formerly observed for perylenebismide with symmetry broken charge transfer state in Marcus-inverted-region. [36] This is the first example of such a slow CR process in compact donor-BDP dyad. In the case of BCZ-2, BCZ-3 and BCZ-4, the singlet state decays directly back to the ground state and no CS process was observed in toluene (Figure S18, Figure S20 and Figure S22).…”

Efficient Intersystem Crossing and Long‐lived Charge‐Separated State Induced by Through‐Space Intramolecular Charge Transfer in a Parallel Geometry Carbazole‐Bodipy Dyad

“…[33][34][35] Note that the lifetime of the CS state of the BCZ-1 is nearly 8 times longer than the lifetime formerly observed for perylenebismide dimer with symmetry broken charge transfer state in Marcus-inverted-region. [36] This is the first example of such a slow CR process in compact donor-BDP dyad. In the case of BCZ-2, BCZ-3 and BCZ-4, the singlet state decays directly back to the ground state and no CS process was observed in toluene (Figure S18, Figure S20 and Figure S22).…”