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Investigation of Morphology‐Controlled Ultrafast Relaxation Processes of Aggregated Porphyrin
Author(s) -
Mondal Bodhisatwa,
Bera Rajesh,
Ghosh Srijon,
Nayak Sandip K.,
Patra Amitava
Publication year - 2020
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.202000482
Subject(s) - porphyrin , relaxation (psychology) , ultrafast laser spectroscopy , chemical physics , exciton , excited state , ultrashort pulse , morphology (biology) , fluorescence , materials science , j aggregate , scanning electron microscope , absorption (acoustics) , photochemistry , chemistry , molecule , spectroscopy , optics , atomic physics , organic chemistry , psychology , social psychology , laser , physics , quantum mechanics , biology , composite material , genetics
Here, we have synthesized rod and flake shaped morphology of porphyrin aggregates from 5, 10, 15, 20‐tetra (4‐ n ‐octyloxyphenyl) porphyrin (4‐opTPP) molecule which are evident from scanning electron microscopy (SEM). The formation of J‐type aggregation is evident from steady state and time‐resolved fluorescence spectroscopic studies. Ultrafast transient absorption spectroscopic studies reveal that the excited state lifetime is controlled by the morphology and the time constant for S 1 →S 0 relaxation changes from 3.05 ps to 744 ps with changing the shape from rod to flake, respectively. In spite of similar exciton coupling energy in both the aggregates, the flake shaped aggregates undergo a faster exciton relaxation process and the non‐radiative relaxation channels are found to depend on the shape of aggregates. The fundamental understanding of morphology controlled ultrafast relaxation processes of aggregated porphyrin is important for designing efficient light harvesting devices.