Singlet exciton fission in solution.

Singlet exciton fission, the spin-conserving process that produces two triplet excited states from one photoexcited singlet state, is a means to circumvent the Shockley-Queisser limit in single-junction solar cells. Although the process through which singlet fission occurs is not well characterized, some local order is thought to be necessary for intermolecular coupling. Here, we report a triplet yield of 200% and triplet formation rates approaching the diffusion limit in solutions of bis(triisopropylsilylethynyl (TIPS)) pentacene. We observe a transient bound excimer intermediate, formed by the collision of one photoexcited and one ground-state TIPS-pentacene molecule. The intermediate breaks up when the two triplets separate to each TIPS-pentacene molecule. This efficient system is a model for future singlet-fission materials and for disordered device components that produce cascades of excited states from sunlight.

[1]  Priya J. Jadhav,et al.  Triplet Exciton Dissociation in Singlet Exciton Fission Photovoltaics , 2012, Advanced materials.

[2]  Matthew T. Whited,et al.  Efficient singlet fission discovered in a disordered acene film. , 2012, Journal of the American Chemical Society.

[3]  M. Head‐Gordon,et al.  Long-range charge-transfer excited states in time-dependent density functional theory require non-local exchange , 2003 .

[4]  W. Barford,et al.  Electronic and optical properties of conjugated polymers , 2005 .

[5]  M. R. Vilar,et al.  Spectroscopy of low-energy electrons backscattered from an organic solid surface: pentacene , 1983 .

[6]  Mark W. B. Wilson,et al.  Singlet exciton fission-sensitized infrared quantum dot solar cells. , 2012, Nano letters.

[7]  M. Head‐Gordon,et al.  A correlated electron view of singlet fission. , 2013, Accounts of chemical research.

[8]  Christopher J. Bardeen,et al.  Evidence for exciton fission and fusion in a covalently linked tetracene dimer , 2006 .

[9]  R. Merrifield.  Diffusion and mutual annihilation of triplet excitons in organic crystals , 1968 .

[10]  G. Fleming,et al.  An unusual pathway of excitation energy deactivation in carotenoids: Singlet-to-triplet conversion on an ultrafast timescale in a photosynthetic antenna , 2001, Proceedings of the National Academy of Sciences of the United States of America.

[11]  Manuel Ligges,et al.  The energy barrier in singlet fission can be overcome through coherent coupling and entropic gain. , 2012, Nature chemistry.

[12]  Michael J. Tauber,et al.  High-yield singlet fission in a zeaxanthin aggregate observed by picosecond resonance Raman spectroscopy. , 2010, Journal of the American Chemical Society.

[13]  C. Bardeen,et al.  Excited state dynamics in solid and monomeric tetracene: The roles of superradiance and exciton fission. , 2010, The Journal of chemical physics.

[14]  Alán Aspuru-Guzik,et al.  Tuning charge transport in solution-sheared organic semiconductors using lattice strain , 2011, Nature.

[15]  Mark W. B. Wilson,et al.  In situ measurement of exciton energy in hybrid singlet-fission solar cells , 2012, Nature Communications.

[16]  Timothy C. Berkelbach,et al.  Microscopic theory of singlet exciton fission. I. General formulation. , 2012, The Journal of chemical physics.

[17]  John E. Anthony,et al.  Functionalized Pentacene Active Layer Organic Thin‐Film Transistors , 2003 .

[18]  Josef Michl,et al.  The role of chromophore coupling in singlet fission. , 2013, Accounts of chemical research.

[19]  C. E. Swenberg,et al.  Bimolecular radiationless transitions in crystalline tetracene , 1968 .

[20]  Y. Olivier,et al.  Charge-transfer excitations steer the Davydov splitting and mediate singlet exciton fission in pentacene. , 2013, Physical review letters.

[21]  J. Hummelen,et al.  Photoinduced Singlet And Triplet Energy Transfer In Fullerene-oligothiophene-fullerene Triads , 2001 .

[22]  W. G. Schneider,et al.  Laser Generation of Excitons and Fluorescence in Anthracene Crystals , 1965 .

[23]  Jenny Clark,et al.  Ultrafast dynamics of exciton fission in polycrystalline pentacene. , 2011, Journal of the American Chemical Society.

[24]  Josef Michl,et al.  Recent advances in singlet fission. , 2013, Annual review of physical chemistry.

[25]  John E. Anthony,et al.  Contact-induced crystallinity for high-performance soluble acene-based transistors and circuits. , 2008, Nature materials.

[26]  S. Mannsfeld,et al.  Thin Film Structure of Triisopropylsilylethynyl‐Functionalized Pentacene and Tetraceno[2,3‐b]thiophene from Grazing Incidence X‐Ray Diffraction , 2011, Advanced materials.

[27]  Paul M Zimmerman,et al.  Mechanism for singlet fission in pentacene and tetracene: from single exciton to two triplets. , 2011, Journal of the American Chemical Society.

[28]  Klaus Müllen,et al.  Exciton fission and fusion in bis(tetracene) molecules with different covalent linker structures. , 2007, Journal of the American Chemical Society.

[29]  X. Zhu,et al.  Harvesting singlet fission for solar energy conversion: one- versus two-electron transfer from the quantum mechanical superposition. , 2012, Journal of the American Chemical Society.

[30]  Akshay Rao,et al.  Exciton fission and charge generation via triplet excitons in pentacene/C60 bilayers. , 2010, Journal of the American Chemical Society.

[31]  L. Kaake,et al.  Observing the Multiexciton State in Singlet Fission and Ensuing Ultrafast Multielectron Transfer , 2011, Science.

[32]  M. Wasielewski,et al.  Competition between singlet fission and charge separation in solution-processed blend films of 6,13-bis(triisopropylsilylethynyl)pentacene with sterically-encumbered perylene-3,4:9,10-bis(dicarboximide)s. , 2012, Journal of the American Chemical Society.

[33]  Mark A Ratner,et al.  Maximizing singlet fission in organic dimers: theoretical investigation of triplet yield in the regime of localized excitation and fast coherent electron transfer. , 2010, The journal of physical chemistry. B.

[34]  John E. Anthony,et al.  Fabrication of organic thin-film transistors by spray-deposition for low-cost, large-area electronics , 2010 .

[35]  M. Pope,et al.  Effect of Magnetic Field on the Fluorescence of Tetracene Crystals: Exciton Fission , 1969 .

[36]  A. A. Villaeys,et al.  Exciton dynamics in pentacene thin films studied by pump-probe spectroscopy , 1995 .

[37]  Mark A Ratner,et al.  Mapping the Relation between Stacking Geometries and Singlet Fission Yield in a Class of Organic Crystals. , 2013, The journal of physical chemistry letters.

[38]  Josef Michl,et al.  Singlet fission. , 2010, Chemical reviews.

[39]  Paul M Zimmerman,et al.  Singlet fission in pentacene through multi-exciton quantum states. , 2010, Nature chemistry.

[40]  A. Nozik,et al.  Solar conversion efficiency of photovoltaic and photoelectrolysis cells with carrier multiplication absorbers , 2006 .

[41]  Klaus Schulten,et al.  Correlation effects in the spectra of polyenes , 1976 .

[42]  R. Merrifield,et al.  Fission of singlet excitons into pairs of triplet excitons in tetracene crystals , 1969 .

[43]  C. Bardeen,et al.  The dependence of singlet exciton relaxation on excitation density and temperature in polycrystalline tetracene thin films: kinetic evidence for a dark intermediate state and implications for singlet fission. , 2011, The Journal of chemical physics.

[44]  M. Nakano,et al.  Diradical Character Based Design for Singlet Fission of Condensed-Ring Systems with 4nπ Electrons , 2012 .

[45]  Mark A Ratner,et al.  Singlet fission for dye-sensitized solar cells: can a suitable sensitizer be found? , 2006, Journal of the American Chemical Society.

[46]  H. Queisser,et al.  Detailed Balance Limit of Efficiency of p‐n Junction Solar Cells , 1961 .

[47]  P. V. von Hippel,et al.  Diffusion-controlled macromolecular interactions. , 1985, Annual review of biophysics and biophysical chemistry.