Harnessing singlet exciton fission to break the Shockley–Queisser limit

Rao, Akshay; Friend, Richard H.

doi:10.1038/natrevmats.2017.63

Cited by 348 publications

(498 citation statements)

References 91 publications

(118 reference statements)

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“…In the second design, the SF and c-Si layers couple only optically, and triplet excitons are converted to bright states in an emitter layer and transmitted to c-Si by electric dipole-allowed processes. 52,53 A conceptual counterpart to SF-augmented c-Si PV is tandem c-Si PV devices. 54,55 While these are a more mature technology, one comparative strength of the SF-PV concept is a lack of current matching, hence a robust spectral stability.…”

Section: Introductionmentioning

confidence: 99%

Crystalline silicon solar cells with tetracene interlayers: the path to silicon-singlet fission heterojunction devices

et al. 2018

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Singlet exciton fission is an exciton multiplication process that occurs in certain organic materials, converting the energy of single highly-energetic photons into pairs of triplet excitons. This could be used to boost the conversion efficiency of crystalline silicon solar cells by creating photocurrent from energy that is usually lost to thermalisation. An appealing method of implementing singlet fission with crystalline silicon is to incorporate singlet fission media directly into a crystalline silicon device. To this end, we developed a solar cell that pairs the electron-selective contact of a high-efficiency silicon heterojunction cell with an organic singlet fission material, tetracene, and a PEDOT:PSS hole extraction layer. Tetracene and n-type crystalline silicon meet in a direct organic-inorganic heterojunction. In this concept the tetracene layer selectively absorbs blue-green light, generating triplet pairs that can dissociate or resonantly transfer at the organo-silicon interface, while lower-energy light is transmitted to the silicon absorber. UV photoemission measurements of the organicinorganic interface showed an energy level alignment conducive to selective hole extraction from silicon by the organic layer. This was borne out by current-voltage measurements of devices subsequently produced. In these devices, the silicon substrate remained well-passivated beneath the tetracene thin film. Light absorption in the tetracene layer created a net reduction in current for the solar cell, but optical modelling of the external quantum efficiency spectrum suggested a small photocurrent contribution from the layer. This is a promising first result for the direct heterojunction approach to singlet fission on crystalline silicon.

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Section: Introductionmentioning

confidence: 99%

Crystalline silicon solar cells with tetracene interlayers: the path to silicon-singlet fission heterojunction devices

et al. 2018

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“…The second pathway also begins with the formation of singlet exciton under photo‐excitation. It is possible to be transferred to a triplet exciton via the intersystem crossing (ISC) or singlet fission (SF) . The exciton, especially the triplet exciton, can further react with a free or trapped charge in order to create free charge carriers .…”

Section: Introductionmentioning

confidence: 99%

“…It is possible to be transferred to a triplet exciton via the intersystem crossing (ISC) or singlet fission (SF). [21,29,30] The exciton, especially the triplet exciton, can further react with a free or trapped charge in order to create free charge carriers. [31][32][33][34] Third, there exists a competition of (CT) 1 and triplet CT state [(CT) 3 ].…”

Section: Introductionmentioning

confidence: 99%

Spin‐Dependent Electron–Hole Recombination and Dissociation in Nonfullerene Acceptor ITIC‐Based Organic Photovoltaic Systems

et al. 2019

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A nonfullerene acceptor (NFA), named 3,9‐bis(2‐methylene‐(3‐(1,1‐dicyanomethylene)‐indanone))‐5,5,11,11‐tetrakis(4‐hexylphenyl)‐dithieno[2,3‐d:2′,3′‐d′]‐s‐indaceno[1,2‐b:5,6‐b′] dithiophene (ITIC) with the fused aromatic conjugated backbone structure, is an intriguing small molecular semiconductor in the application of organic bulk heterojunction (BHJ) solar cells. However, the underlying spin‐dependent photo‐physics in the photovoltaic process remains deficient. Here, ITIC‐based thin solid film, binary, and ternary organic blends are designed and fabricated with two polymeric donors, poly[(2,6‐(4,8‐bis(5‐(2‐ethylhexyl)thiophen‐2‐yl)‐benzo[1,2‐b:4,5‐b′]‐dithiophene))‐alt‐(5,5‐(1′,3′‐di‐2‐thienyl‐5′,7′‐bis(2‐ethylhexyl)benzo[1′,2′‐c:4′,5′‐c′]dithiophene‐4,8‐dione))] (PBDB‐T) and poly[(2,6‐(4,8‐Bis(3‐((2‐ethylhexyl)oxy)‐phenyl)‐benzo[1,2‐b:4,5‐b′]‐dithiophene))‐alt‐(5,5‐(1′,3′‐di‐2‐thienyl‐5′,7′‐bis(2‐ethylhexyl)benzo[1′,2′‐c:4′,5′‐c′]dithiophene‐4,8‐dione))] (PBPD‐Th). With the spin‐sensitive magneto‐photocurrent and magneto‐electroluminescence measurements, ITIC always exhibits large magnetic field effects with negative signs in the ambient temperature. The effect is attributed to the exciton‐charge reaction. However, both positive and negative signs are detected in the binary and ternary organic blends at small and large fields, respectively. The results elucidate that the mutual combination of the spin‐dependent polaron pair dissociation and exciton‐charge reaction plays a decisive role in the photovoltaic process. Furthermore, with photo‐induced electron paramagnetic resonance (EPR) studies, the full width at half maximum (FWHM) of the line shape for the positive magneto‐photocurrent is firmly associated to the magnitude of the effective g‐factor. The present study may shed a new light on the deep understanding of spin‐dependent photo‐physical process in NFA‐based solar cells for organic opto‐spintronic developments.

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“…[1,2] A process that has the potential to increase this limit to 45% is to use high-energy photons to produce two electron-hole pairs following the absorption of a single photon . [1,2] A process that has the potential to increase this limit to 45% is to use high-energy photons to produce two electron-hole pairs following the absorption of a single photon .…”

mentioning

confidence: 99%

“…efficiency of 32% for a single-junction PV; the Shockley-Queisser limit. [1,2] A process that has the potential to increase this limit to 45% is to use high-energy photons to produce two electron-hole pairs following the absorption of a single photon . In organic materials, such a photophysical process is called singlet fission (SF), the spin allowed conversion of a singlet excited state into two triplets by an assembly of two or more chromophores.…”

mentioning

confidence: 99%

Liquid Crystallinity as a Self‐Assembly Motif for High‐Efficiency, Solution‐Processed, Solid‐State Singlet Fission Materials

Masoomi‐Godarzi

Liu

Tachibana

et al. 2019

Advanced Energy Materials

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The dominant loss mechanism in single-junction photovoltaic (PV) devices following excitation with high-energy photons is the wasted excess energy above the bandgap that is emitted as heat (thermalization losses), leading to a maximum theoretical 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.

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Harnessing singlet exciton fission to break the Shockley–Queisser limit

Cited by 348 publications

References 91 publications

Crystalline silicon solar cells with tetracene interlayers: the path to silicon-singlet fission heterojunction devices

Crystalline silicon solar cells with tetracene interlayers: the path to silicon-singlet fission heterojunction devices

Spin‐Dependent Electron–Hole Recombination and Dissociation in Nonfullerene Acceptor ITIC‐Based Organic Photovoltaic Systems

Liquid Crystallinity as a Self‐Assembly Motif for High‐Efficiency, Solution‐Processed, Solid‐State Singlet Fission Materials

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