Singlet fission molecules among known compounds: finding a few needles in a haystack

Padula, Daniele; Omar, Ömer H.; Nematiaram, Tahereh; Troisi, Alessandro

doi:10.1039/c9ee01508f

Cited by 96 publications

(143 citation statements)

References 28 publications

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“…To best capture this relationship, a scatter plot of the primary energy criterion versus the diradical index is given in Figure 2 (E(S 1 ) and E(T 1 ) values are taken from our previous work in Ref. [24]).…”

Section: Resultsmentioning

confidence: 99%

“…The values for first singlet and triplet excited states are taken from our previous study in Ref. [24]. materials such as oligoacenes, cumulenes, [58] diketopyrrolopyrroles, [59] and also novel materials e. g. Pechmann dyes, Russig's blue analogues, silenes and others proposed in Ref.…”

Section: Resultsmentioning

confidence: 99%

“…The structures will be chosen from the pool of 241 promising SF candidates from our previous high-throughput work in Ref. [24]. These are molecules with crystal structures deposited in the CSD and are depicted in the Supporting Information; they are predicted to satisfy the main energy criteria for SF after preliminary screening using X-ray geometries at the M06-2X/ def2-SVP level as per a protocol benchmarked against reference CC2 calculations by Grotjahn et al, [37] which is in agreement with an alternative benchmarking study by Brückner et al for the TDDFT functional choice.…”

Section: Methodsmentioning

confidence: 99%

“…[38] Additionally, the method is calibrated linearly using a sizeable set of~100 molecules with experimental data, obtaining good correlations (R 2~0 .9). [24] Together with the benchmarking and calibration, this protocol correctly evaluates the SF energy characteristic for well-known molecules such as tetracene and pentacene i. e. endothermic for tetracene and exothermic for pentacene. 201 of these structures continue to fulfil the SF condition after a high-level geometry optimisation (BLYP35/def2-TZVP) and have optically bright first singlet excited states i. e. they have computed oscillator strengths of the first singlet state greater than 0.05.…”

Section: Methodsmentioning

confidence: 99%

“…An unfortunate aspect of discovering new SF candidates with evident diradical character in their ground states is that, when they are eventually used for device fabrication, their likely chemical instability and propensity to react with other organic materials ultimately makes them unsuitable, [20] although current research into stabilisation via the captodative effect [11,21] and cross-conjugation [22,23] aims to alleviate this. Our previous work attempted to address this by testing, theoret-ically, a large set of known organic compounds with reduced or no pre-design, [24] similar to other high-throughput virtual screening efforts. [25][26][27][28][29][30][31][32][33][34][35] The 40 K organic molecules were taken from the Cambridge Structural Database (CSD), [36] reduced from a total set of almost one million structures.…”

Section: Introductionmentioning

confidence: 99%

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Elucidating the Relationship between Multiradical Character and Predicted Singlet Fission Activity

2020

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The diradical and multiradical characters of a large and diverse set of 241 predicted singlet fission candidates are determined by multiconfigurational wavefunction methods, specifically natural orbital occupation number (NOON) analysis using the CASSCF method. The ascertained multiradical character strongly supports the current prediction that a good singlet fission candidate, independent of its structure, will tend to be of the weak biradicaloid class as well as having very little tetraradical character. Although the rule remains robust, it is not absolute as a small portion of our potential candidates are predicted to be closed shell. Additionally, a smaller handful of outliers with apparent tetraradical characters are identified, suggesting there may be the possibility, albeit rare, of singlet fission amongst weak tetraradicaloids.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Elucidating the Relationship between Multiradical Character and Predicted Singlet Fission Activity

2020

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On the Largest Possible Mobility of Molecular Semiconductors and How to Achieve It

Nematiaram

Padula

Landi

et al. 2020

Adv Funct Materials

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We use a large database of known molecular semiconductors to define a plausible physical limit to the charge carrier mobility achievable within this materials class, and a clear path toward this limit. From a detailed study of the desirable properties in a large dataset, it is possible to establish whether such properties can be optimized independently and what would be a reasonably achievable optimum for each of them, regardless of the transport mechanism considered. We compute all relevant parameters from a set of almost five thousand known molecular semiconductors, finding that the best known materials are not ideal with respect to all properties. These parameters in decreasing order of importance are realized to be the molecular area, the non-local electron-phonon coupling, the two-dimensional nature of transport, the local electron-phonon coupling and the highest transfer integral. We also find that the key properties related to the charge transport are either uncorrelated or 'constructively' correlated (i.e. they improve together) concluding that a ten-fold increase in mobility is within reach in a statistical sense, on the basis of the available data. We demonstrate that high throughput screenings, when coupled with physical models of transport produce not only specific target materials, as it is done also here, but a more general physical understanding of the materials space and the opportunities of further development.

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Guidelines for Material Design in Semitransparent Organic Solar Cells

Forberich,

Troisi,

Liu

et al. 2024

Adv Funct Materials

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Organic solar cells (OSCs) are uniquely suited for semitransparent applications due to their adjustable absorption spectrum. However, most high‐performance semitransparent cells reported to date are based on materials that have shown high power conversion efficiency for opaque devices. A model is therefore presented to assess the optimum efficiency and transparency for a specific donor and acceptor bandgap. The absorption characteristics of both donor and acceptor are modeled with spectral data of typical absorber materials from the literature which are adjusted to achieve the desired bandgap value. The results show three distinct regions of high light utilization efficiency (LUE) if the photopic curve is employed as a weighting function (corresponding to window applications), and a broad maximum for the plant action spectrum as a weighting function (corresponding to greenhouse applications). When comparing these findings to reported experimental values, it is evident that the bandgaps of the materials used for the experimental studies do not correspond to the maxima identified by the simulation model. The analysis of the energy levels of molecules recorded in the literature confirms that all bandgaps and therefore all LUE maxima are chemically feasible so that the performance of semitransparent OSCs can be further improved by designing materials with optimized absorption spectra.

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Singlet fission molecules among known compounds: finding a few needles in a haystack

Abstract: A large set of candidates for singlet fission, one of the most promising processes able to improve the efficiency of solar cells, are identified by screening a database of known molecular materials.

Cited by 96 publications

References 28 publications

Elucidating the Relationship between Multiradical Character and Predicted Singlet Fission Activity

Elucidating the Relationship between Multiradical Character and Predicted Singlet Fission Activity

On the Largest Possible Mobility of Molecular Semiconductors and How to Achieve It

Guidelines for Material Design in Semitransparent Organic Solar Cells

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