Open AccessEfficient Free Triplet Generation Follows Singlet Fission in Diketopyrrolopyrrole Polymorphs with Goldilocks Coupling
Author(s) -
A. M. Levine,
Guiying He,
Guanhong Bu,
Pablo Ramos,
Fanglue Wu,
Aisha Soliman,
Jacqueline Serrano,
Dorian Pietraru,
Chung Chow Chan,
James D. Batteas,
Marta Kowalczyk,
Seogjoo Jang,
Brent L. Nannenga,
Matthew Y. Sfeir,
Esther H. R. Tsai,
Adam B. Braunschweig
Publication year - 2021
Publication title -
journal of physical chemistry. c./journal of physical chemistry. c
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.401
H-Index - 289
eISSN - 1932-7455
pISSN - 1932-7447
DOI - 10.1021/acs.jpcc.1c02737
Subject(s) - singlet fission , spectroscopy , amorphous solid , crystallography , materials science , annealing (glass) , absorption spectroscopy , ultrafast laser spectroscopy , excited state , chemistry , photochemistry , triplet state , molecule , atomic physics , optics , organic chemistry , physics , quantum mechanics , composite material
Microcrystal electron diffraction, grazing incidence wide-angle scattering, and UV-Vis spectroscopy were used to determine the unit cell structure and the relative composition of dimethylated diketopyrrolopyrrole (MeDPP) H- and J-polymorphs within thin films subjected to vapor solvent annealing (VSA) for different times. Electronic structure and excited state deactivation pathways of the different polymorphs were examined by transient absorption spectroscopy, conductive probe atomic force microscopy, and molecular modeling. We find VSA initially converts amorphous films into mixtures of H- and J-polymorphs and promotes further conversion from H to J with longer VSA times. Though both polymorphs exhibit efficient SF to form coupled triplets, free triplet yields are higher in J-polymorph films compared to mixed films because coupling in J-aggregates is lower, and, in turn, more favorable for triplet decoupling.