H-Type-like Aggregation-Accelerated Singlet Fission Process in Dipyrrolonaphthyridinedione Thin Film: The Role of Charge Transfer/Excimer Mixed Intermediate State

Abstract

Through the combination of transient spectroscopy and theoretical simulations, an accelerated singlet fission (SF) process was evidently observed in the strongly coupled H-type-like aggregation thin films of a dipyrrolonaphthyridinedione skeleton. Results elucidate that in this H-type-like aggregation, the substantially stabilized charge transfer (CT) state is close in energy with singlet and excimer states, resulting in a CT/excimer mixed state, which could drive excited-state population escaping from excimer trap and promote an ultrafast and highly efficient SF process. Our results not only enrich the limited capacity of SF materials but also contribute to an in-depth understanding of SF dynamics in H-type aggregation, which is of fundamental importance for designing new SF sensitizers and implementing practical SF applications.

Flavanthrene derivatives as photostable and efficient singlet exciton fission materials

“…49 When the excimer, S 1 and CT states are close in energy, it is favorable for the mixing of these states to promotes SF. 46,47,49 The calculated results show that the CT state energies of EH-Fla is 2.57 eV, 0.46 eV above the excimer (2.11 eV). Such high CT state of EH-Fla is unfavorable for SF to occur via a superexchange interaction.…”

“…Several previous studies have explored excimermediated SF processes in concentrated pentacene solutions, perylenediimide dimers, and films of diketopyrrolopyrrole, terrylenediimide, and dipyrrolon-aphthyridinedione. 18,28,45,46 In the excimer-mediated process, SF occurs in two steps. First, a fast transition from the 1 (S 1 S 0 ) state to the excimer intermediate.…”

Conformational distortion-harnessed singlet fission dynamics in thienoquinoid: rapid generation and subsequent annihilation of multiexciton dark state

“…Femtosecond transient absorption (fs-TA) and nanosecond transient absorption (ns-TA) spectroscopy measurements were all performed using previously described instruments and experimental conditions. [28][29][30]…”

Diphenyldihydropentalenediones: Potential Singlet Fission Materials with High Triplet Energy Levels

“…[6][7] Consequently, over the past several years, many experimental and theoretical investigations have been conducted to uncover new SF materials. [8][9][10][11][12][13][14][15][16][17][18][19][20] [21] To achieve the proper exergonicity for efficient SF, the singletexcited state energy level (ES, Fig. 1) of a substance must be higher than twice the energy level of its triplet-excited state (ET) (i.e., ES > 2ET).…”