Singlet Fission from Upper Excited States of Bodipy Crystalline Film and Single Crystal

Abstract

The well-known boron-dipyrromethene (bodipy) dyes have excellent photophysical and photochemical properties, which are significant for practical use in many fields. meso-Phenyl-substituted bodipy (PhBDP) as one of the most classical bodipy derivatives was investigated in the forms of amorphous film, crystalline film, and single crystal by using time-resolved fluorescence and femtosecond transient absorption techniques. The fluorescence of both PhBDP films is strongly quenched because of Jaggregation, which is randomly distributed in the amorphous film but well arranged in the crystalline film. In the crystalline film, the triplet states were populated from the upper excited singlet states (3.54 eV) of the nanoaggregates via singlet fission (SF) within 30 fs. Moreover, SF was also detected after excitation of the lower singlet states (2.58 eV) which are below the SF threshold (3.28 eV). This phenomenon was explained in terms of two-quantum absorption. However, in the amorphous film, the SF process was not observed, indicating the crucial impact of the nanoaggregate morphology on the formation of SF. In the single crystal, SF was also generated owing to the molecular slip-stacked packing which is optimal for the delocalization of excitation. It facilitates exciton fission and energy transfer between the neighboring PhBDP dimer moieties as well. Our findings of PhBDP solids provide a significant theoretical and experimental basis for exploring new SF systems. The prominent quenching, efficient SF, and well-characterized energy transfer of PhBDP solid expands the applications of PhBDP-based organic materials in optoelectronic devices.

Intramolecular singlet fission and triplet exciton harvesting in tetracene oligomers for solar energy conversion

“…Under the guidance of dimer 14, Hasobe's group further synthesized a series of linear homo-oligomers (tetramer (Tc) 4 (50), hexamer (Tc) 6 (51)) and hetero-hexamer (TcF 3 -(Tc) 4 -TcF 3 , 52) with a 3,4,5-triuoropheny substituent on the terminal position of the two tetracenes (Fig. 13).…”

“…1 Subsequently, SF has shown vigorous development, and great efforts have been devoted to developing new efficient SF materials and revealing the SF mechanism. Many chromophores have been found to meet the energy requirement of SF, where the singlet state energy (E S 1 ) should be larger or equal to twice the triplet state energy (E T 1 ) (E S 1 # 2E T 1 ), such as acenes (anthracene, 19 tetracene, 20 pentacene, [21][22][23][24] hexacene [25][26][27] and their derivatives), polyene, [28][29][30][31][32][33][34] 1,3-diphenylisobenzofuran, 35 diketopyrrolopyrrole, [36][37][38][39][40] perylenediimide, [41][42][43][44][45][46] boron dipyrromethene (BODIPY), [47][48][49][50] and other chromophores. 37,[51][52][53][54][55][56][57][58][59][60][61] These molecules have been summarized in some comprehensive reviews on this eld.…”

The acceleration of BODIPY dye-sensitized photocatalytic hydrogen production in aqueous ascorbic acid solutions using alkyl-chain formed second coordination sphere effects

“…The pico-second scale generated a positive absorption band between 550 and 700 nm that was assigned to the excited-state absorption (S 0 / S 1 transition). 38,39 The data were tted with a double-exponential decay function. The time decay constants s 1 , and s 2 of the dye were determined to be 84.3 ps, and 667.3 ps for 3/TiO 2 , 13.9 ps, and 356.6 ps for 7a/TiO 2 , 8.3 ps, and 144.1 ps for 7b/TiO 2 , 0.14 ps, and 29.0 ps for 7c/TiO 2 , respectively.…”

Formylation as a Chemical Tool to Modulate the Performance of Photosensitizers Based on Boron Dipyrromethene Dimers

“…The elucidation of this mechanism allowing triplet-state population has been the subject of controversy, with the SOC-ISC being the most commonly accepted pathway [14][15][16], although other mechanisms cannot be fully excluded [41,42]. For instance, single fission has been shown to be involved in J-type BODIPY dimers in the solid state [43].…”