Singlet Fission for Dye-Sensitized Solar Cells:  Can a Suitable Sensitizer Be Found?

Paci, Irina; Johnson, Justin C.; Chen, Xudong; Rana, Geeta; Popović, D. B.; David, Donald E.; Nozik, Arthur J.; Ratner, Mark A.; Michl, Josef

doi:10.1021/ja063980h

Cited by 407 publications

(482 citation statements)

References 65 publications

Supporting

Mentioning

473

Contrasting

Order By: Relevance

“…17 An application of singlet exciton fission relies on the superior diffusion length of the generated triplet excitons and the potential to surpass the Shockley-Queisser limit for single junction photovoltaic cells by a factor of 1.5 if the excess solar energy photons above the band gap are converted into more than one electron-hole pair per photon. [38][39][40][41] This potential has led to an increased research focus on how SEF occurs in Tc 18-22, 27, 37 and pentacene (Pc). 23,29,42 The opposite process, exciton fusion of the two triplet excitons forming a singlet exciton can also occur.…”

Section: Introductionmentioning

confidence: 99%

Ultrafast dynamics of excitons in tetracene single crystals

Birech

Schwoerer

Schmeiler

et al. 2014

The Journal of Chemical Physics

View full text Add to dashboard Cite

Articles you may be interested inUltrafast exciton dynamics in free standing 200 nm thin tetracene single crystals were studied at room temperature by femtosecond transient absorption spectroscopy in the visible spectral range. The complex spectrally overlapping transient absorption traces of single crystals were systematically deconvoluted. From this, the ultrafast dynamics of the ground, excited, and transition states were identified including singlet exciton fission into two triplet excitons. Fission is generated through both, direct fission of higher singlet states S n on a sub-picosecond timescale, and thermally activated fission of the singlet exciton S 1 on a 40 ps timescale. The high energy Davydov component of the S 1 exciton is proposed to undergo fission on a sub-picoseconds timescale. At high density of triplet excitons their mutual annihilation (triplet-triplet annihilation) occurs on a <10 ps timescale.

show abstract

Section: Introductionmentioning

confidence: 99%

Ultrafast dynamics of excitons in tetracene single crystals

Birech

Schwoerer

Schmeiler

et al. 2014

The Journal of Chemical Physics

View full text Add to dashboard Cite

show abstract

“…4 In parallel to the impressive development in device engineering, efforts have been made to unravel the physical mechanisms behind such interesting phenomena. [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] Most of the experimental and theoretical works have focused on the material family of polyacenes.…”

Section: Introductionmentioning

confidence: 99%

Polarization-dependent exciton dynamics in tetracene single crystals

Zhang

et al. 2014

The Journal of Chemical Physics

View full text Add to dashboard Cite

Abstract:We conduct polarization-dependent ultrafast spectroscopy to study the dynamics of singlet fission in tetracene single crystals. The spectrotemporal species for singlet and triplet excitons in transient absorption spectra are found to be strongly dependent on probe polarization. By carefully analyzing the polarization dependence, the signals contributed by different transitions related to singlet excitons have been disentangled, which is further applied to construct the correlation between dynamics of singlet and triplet excitons. The anisotropy of exciton dynamics provides an alternative approach to tackle the long-standing challenge in understanding the mechanism of singlet fission in organic semiconductors.

show abstract

“…Although earlier studies outlined the energetic criteria for singlet fission 15,16 , the lack of a proper description of the ME wavefunction has prevented elucidation of a detailed mechanism. Some have postulated that the singlet fission process involves interconversion of the optically allowed excited state S 1 to a nearby state that has the character of two triplets [11][12][13][14] .…”

mentioning

confidence: 99%

Singlet fission in pentacene through multi-exciton quantum states

2010

View full text Add to dashboard Cite

Multi-exciton generation-the creation of multiple charge carrier pairs from a single photon-has been reported for several materials and may dramatically increase solar cell efficiency. Singlet fission, its molecular analogue, may govern multiexciton generation in a variety of materials, but a fundamental mechanism for singlet fission has yet to be described. Here, we use sophisticated ab initio calculations to show that singlet fission in pentacene proceeds through rapid internal conversion of the photoexcited state into a dark state of multi-exciton character that efficiently splits into two triplets. We show that singlet fission to produce a pair of triplet excitons must involve an intermediate state that (i) has a multiexciton character, (ii) is energetically accessible from the optically allowed excited state, and (iii) efficiently dissociates into multiple electron-hole pairs. The rational design of photovoltaic materials that make use of singlet fission will require similar ab initio analysis of multi-exciton states such as the dark state studied here.A lthough the maximum efficiency of single-junction solar cells is limited to 31% (ref. 1), multi-exciton generation (MEG) may enable dramatically higher efficiencies. MEG produces multiple charge carrier pairs from single photons, whereas typical solar cells only produce one exciton per photon. Singlet fission, in which two triplets are created from one excited singlet state, is the molecular analogue of MEG and has the inherent advantage that because the generated charge carriers are triplets, the forbidden triplet to ground-state singlet transition would decrease carrier recombination rates, preserving higher efficiencies.Singlet fission has been observed in crystalline pentacene 2-4 and may also govern MEG in materials other than pentacene or other polyacenes. Any MEG process necessarily entails the formation of a multi-exciton (ME) quantum state following photoexcitation, so taking advantage of the fission process to design more efficient photovoltaic materials will require a detailed understanding of both the MEG mechanism and the precise nature of the participating ME states.The singlet excitons generated by photoexcitation of crystalline pentacene undergo rapid, temperature-independent fission into two triplet excitons 2-4 . The lowest optically allowed singlet excited state (S 1 ) of crystalline pentacene has an excitation energy of more than twice its triplet energy (E(S 1 ) . 2 × E(T 1 )), making unactivated singlet fission energetically possible. In contrast, this is not the case in tetracene, because E(S 1 ) is less than 2 × E(T 1 ) and consequently singlet fission is thermally activated [5][6][7] . In pentacene crystals, both magnetic field measurements 8 and long (.1 ns) photoinduced absorption lifetimes show that triplets are present after optical excitation 3,4 . The energy of this absorption matches our theoretically predicted triplet-triplet excitation (vide infra), further confirming the generation of triplets. The observed yield of triple...

show abstract

Singlet Fission for Dye-Sensitized Solar Cells: Can a Suitable Sensitizer Be Found?

Cited by 407 publications

References 65 publications

Ultrafast dynamics of excitons in tetracene single crystals

Ultrafast dynamics of excitons in tetracene single crystals

Polarization-dependent exciton dynamics in tetracene single crystals

Singlet fission in pentacene through multi-exciton quantum states

Contact Info

Product

Resources

About