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Liquid Crystallinity as a Self‐Assembly Motif for High‐Efficiency, Solution‐Processed, Solid‐State Singlet Fission Materials
Author(s) -
MasoomiGodarzi Saghar,
Liu Maning,
Tachibana Yasuhiro,
Mitchell Valerie D.,
Goerigk Lars,
Ghiggino Kenneth P.,
Smith Trevor A.,
Jones David J.
Publication year - 2019
Publication title -
advanced energy materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.08
H-Index - 220
eISSN - 1614-6840
pISSN - 1614-6832
DOI - 10.1002/aenm.201901069
Subject(s) - materials science , thin film , crystallinity , amorphous solid , photoluminescence , singlet fission , organic semiconductor , annealing (glass) , chemical engineering , photochemistry , crystallography , optoelectronics , nanotechnology , organic chemistry , composite material , triplet state , molecule , chemistry , engineering
Solution and solution‐deposited thin films of the discotic liquid crystalline electron acceptor–donor–acceptor (A‐D‐A) p‐type organic semiconductor FHBC(TDPP) 2 , synthesized by coupling thienyl substituted diketopyrrolopyrrole (TDPP) onto a fluorenyl substituted hexa‐ peri ‐hexabenzocoronene (FHBC) core, are examined by ultrafast and nanosecond transient absorption spectroscopy, and time‐resolved photoluminescence studies to examine their ability to support singlet fission (SF). Grazing incidence wide‐angle X‐ray (GIWAX) studies indicate that as‐cast thin films of FHBC(TDPP) 2 are “amorphous,” while hexagonal packed discotic liquid crystalline films evolve during thermal annealing. SF in as‐cast thin films is observed with an ≈150% triplet generation yield. Thermally annealing the thin films improves SF yields up to 170%. The as‐cast thin films show no long‐range order, indicating a new class of SF material where the requirement for local order and strong near neighbor coupling has been removed. Generation of long‐lived triplets (µs) suggests that these materials may also be suitable for inclusion in organic solar cells to enhance performance.