TY - JOUR
T1 - Singlet Fission within Diketopyrrolopyrrole Nanoparticles in Water
AU - Mauck, Catherine M.
AU - Hartnett, Patrick E.
AU - Wu, Yi Lin
AU - Miller, Claire E.
AU - Marks, Tobin J.
AU - Wasielewski, Michael R.
N1 - Funding Information:
This work was supported by the Chemical Sciences, Geosciences, and Biosciences Division, Office of Basic Energy Sciences, DOE under grant no. DE-FG02-99ER14999 (M.R.W.). C.M.M. acknowledges the support of a NSF Graduate Research Fellowship under grant no. DGE-1324585. Particle size distribution measurements were performed in the Keck Biophysics facility at Northwestern University which has received support from the W.M. Keck Foundation, Northwestern University Office for Research, NIH, and the Rice Foundation. P.E.H. (nanoparticle synthesis) was supported by the Argonne-Northwestern Solar Energy Research (ANSER) Center, an Energy Frontier Research Center funded by the U.S. Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences, under award number DE-SC0001059. This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. We thank Dr. X. Zuo (Argonne National Laboratory) for his expert support on the X-ray scattering measurements.
PY - 2017/8/22
Y1 - 2017/8/22
N2 - Nanoparticles (NPs) of the singlet fission chromophore 3,6-bis(5-phenylthiophen-2-yl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione (PhTDPP) having average hydrodynamic diameters of 63-193 nm were prepared by rapidly injecting variable concentrations of PhTDPP solutions in tetrahydrofuran into water. These PhTDPP NPs are stable over months in water and exhibit fluorescence quantum yields ≪1%. Femtosecond transient absorption spectroscopy shows that singlet fission is more rapid in smaller NPs, likely reflecting their greater surface area-to-volume ratio and consequent exposure of more molecules to the high dielectric aqueous environment. These observations suggest that charge transfer states, whose energy is sensitive to the dielectric constant of the surrounding medium, serve as virtual intermediates in PhTDPP NP singlet fission. However, the lifetime of the triplet excitons produced by singlet fission is longest in the larger NPs having greater long-range order, which allows the triplet excitons to diffuse further from one another thus slowing triplet-triplet annihilation.
AB - Nanoparticles (NPs) of the singlet fission chromophore 3,6-bis(5-phenylthiophen-2-yl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione (PhTDPP) having average hydrodynamic diameters of 63-193 nm were prepared by rapidly injecting variable concentrations of PhTDPP solutions in tetrahydrofuran into water. These PhTDPP NPs are stable over months in water and exhibit fluorescence quantum yields ≪1%. Femtosecond transient absorption spectroscopy shows that singlet fission is more rapid in smaller NPs, likely reflecting their greater surface area-to-volume ratio and consequent exposure of more molecules to the high dielectric aqueous environment. These observations suggest that charge transfer states, whose energy is sensitive to the dielectric constant of the surrounding medium, serve as virtual intermediates in PhTDPP NP singlet fission. However, the lifetime of the triplet excitons produced by singlet fission is longest in the larger NPs having greater long-range order, which allows the triplet excitons to diffuse further from one another thus slowing triplet-triplet annihilation.
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U2 - 10.1021/acs.chemmater.7b01845
DO - 10.1021/acs.chemmater.7b01845
M3 - Article
AN - SCOPUS:85027849167
VL - 29
SP - 6810
EP - 6817
JO - Chemistry of Materials
JF - Chemistry of Materials
SN - 0897-4756
IS - 16
ER -