TY - JOUR
T1 - Singlet Fission in Core-Shell Micelles of End-Functionalized Polymers
AU - Tilley, Andrew J.
AU - Pensack, Ryan D.
AU - Kynaston, Emily L.
AU - Scholes, Gregory D.
AU - Seferos, Dwight S.
N1 - Publisher Copyright:
© 2018 American Chemical Society.
PY - 2018/7/10
Y1 - 2018/7/10
N2 - Singlet fission is the process in aggregates of molecular semiconductors where the initial product of light absorption (a singlet exciton) is converted into two correlated spin-triplet excitons. While most studies of singlet fission are conducted on assemblies of small molecule singlet fission chromophores, polymer self-assembly has yet to be explored as a means of creating nanostructures conducive for singlet fission. In this work, we use solution self-assembly of mono- and difunctionalized polymers to create core-shell micelles that display efficient singlet fission. The polymers are synthesized by copper(I)-catalyzed "click" chemistry between a 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-Pn) alkyne precursor and the corresponding azide-terminated poly(ethylene glycol) (PEG) polymer. Spontaneous solution self-assembly creates starlike and flowerlike core-shell micelles that are characterized by dynamic light scattering (DLS) and transmission electron microscopy (TEM) experiments. Ultrafast transient absorption spectroscopy and time-resolved fluorescence experiments evidence nearly equivalent singlet fission dynamics in starlike and flowerlike micelles. Studies on mixed micelles of the Pn-functionalized polymer with a C16-PEG surfactant reveal how triplet pair formation and decay rates vary with micelle composition. The core-shell micelles developed herein demonstrate the potential of polymer self-assembly for creating functional singlet fission nanostructures and provide insight into how secondary components and solubilizing blocks influence singlet fission dynamics and triplet pair losses in self-assembled systems.
AB - Singlet fission is the process in aggregates of molecular semiconductors where the initial product of light absorption (a singlet exciton) is converted into two correlated spin-triplet excitons. While most studies of singlet fission are conducted on assemblies of small molecule singlet fission chromophores, polymer self-assembly has yet to be explored as a means of creating nanostructures conducive for singlet fission. In this work, we use solution self-assembly of mono- and difunctionalized polymers to create core-shell micelles that display efficient singlet fission. The polymers are synthesized by copper(I)-catalyzed "click" chemistry between a 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-Pn) alkyne precursor and the corresponding azide-terminated poly(ethylene glycol) (PEG) polymer. Spontaneous solution self-assembly creates starlike and flowerlike core-shell micelles that are characterized by dynamic light scattering (DLS) and transmission electron microscopy (TEM) experiments. Ultrafast transient absorption spectroscopy and time-resolved fluorescence experiments evidence nearly equivalent singlet fission dynamics in starlike and flowerlike micelles. Studies on mixed micelles of the Pn-functionalized polymer with a C16-PEG surfactant reveal how triplet pair formation and decay rates vary with micelle composition. The core-shell micelles developed herein demonstrate the potential of polymer self-assembly for creating functional singlet fission nanostructures and provide insight into how secondary components and solubilizing blocks influence singlet fission dynamics and triplet pair losses in self-assembled systems.
UR - http://www.scopus.com/inward/record.url?scp=85049847253&partnerID=8YFLogxK
U2 - 10.1021/acs.chemmater.8b01814
DO - 10.1021/acs.chemmater.8b01814
M3 - Article
AN - SCOPUS:85049847253
SN - 0897-4756
VL - 30
SP - 4409
EP - 4421
JO - Chemistry of Materials
JF - Chemistry of Materials
IS - 13
ER -