Pushing the knowledge of interfaces

Banerji, Natalie

doi:10.1038/nmat4871

Cited by 7 publications

(5 citation statements)

References 11 publications

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“… 1 An unresolved scientific challenge for this technology is understanding–and controlling–the mechanism of photoinduced electron–hole (e–h) separation. Specifically, the extent to which Coulombic interactions between the electron and hole directly after exciton dissociation at a donor:acceptor (D:A) interface limit photocurrent generation has remained controversial, 2 because of inconclusive evidence from experimental and theoretical studies producing contradictory e–h separation models. 3 − 8 There is extensive evidence from transient absorption and photoluminescence (PL) spectroscopic studies for the existence of photogenerated e–h pairs that are spatially localized and subject to stronger Coulombic binding interaction which, once formed, can limit photocurrent generation.…”

Section: Introductionmentioning

confidence: 99%

“…An unresolved scientific challenge for this technology is understanding–and controlling–the mechanism of photoinduced electron–hole (e–h) separation. Specifically, the extent to which Coulombic interactions between the electron and hole directly after exciton dissociation at a donor:acceptor (D:A) interface limit photocurrent generation has remained controversial, because of inconclusive evidence from experimental and theoretical studies producing contradictory e–h separation models. − There is extensive evidence from transient absorption and photoluminescence (PL) spectroscopic studies for the existence of photogenerated e–h pairs that are spatially localized and subject to stronger Coulombic binding interaction which, once formed, can limit photocurrent generation. ,− We refer herein to such states as bound interfacial charge-transfer (CT) states. The presence of such CT states is evidenced by electric-field-dependent studies and pump–push transient studies indicating extra energy can assist in dissociating these intermediate CT states into separated e–h pairs. − Some, but not all, transient studies have shown that the yield of separated e–h pairs increases with an increasing enthalpic offset between the photoexcited donor (or acceptor) singlet state and the nominal D:A charge separated state in series of chemically similar blends, suggesting that an increased offset may help photogenerated e–h pairs avoid prompt recombination at the D:A interface by overcoming their Coulombic binding energy. − Furthermore, photoluminescence studies probing sub-band-gap CT transitions have demonstrated the existence of CT states with different degrees of an e–h pair separation radius, and hence, binding energy .…”

Section: Introductionmentioning

confidence: 99%

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Spectroscopic Investigation of the Effect of Microstructure and Energetic Offset on the Nature of Interfacial Charge Transfer States in Polymer: Fullerene Blends

Dimitrov

Azzouzi

et al. 2019

J. Am. Chem. Soc.

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Despite performance improvements of organic photovoltaics, the mechanism of photoinduced electron–hole separation at organic donor–acceptor interfaces remains poorly understood. Inconclusive experimental and theoretical results have produced contradictory models for electron–hole separation in which the role of interfacial charge-transfer (CT) states is unclear, with one model identifying them as limiting separation and another as readily dissociating. Here, polymer–fullerene blends with contrasting photocurrent properties and enthalpic offsets driving separation were studied. By modifying composition, film structures were varied from consisting of molecularly mixed polymer–fullerene domains to consisting of both molecularly mixed and fullerene domains. Transient absorption spectroscopy revealed that CT state dissociation generating separated electron–hole pairs is only efficient in the high energy offset blend with fullerene domains. In all other blends (with low offset or predominantly molecularly mixed domains), nanosecond geminate electron–hole recombination is observed revealing the importance of spatially localized electron–hole pairs (bound CT states) in the electron–hole dynamics. A two-dimensional lattice exciton model was used to simulate the excited state spectrum of a model system as a function of microstructure and energy offset. The results could reproduce the main features of experimental electroluminescence spectra indicating that electron–hole pairs become less bound and more spatially separated upon increasing energy offset and fullerene domain density. Differences between electroluminescence and photoluminescence spectra could be explained by CT photoluminescence being dominated by more-bound states, reflecting geminate recombination processes, while CT electroluminescence preferentially probes less-bound CT states that escape geminate recombination. These results suggest that apparently contradictory studies on electron–hole separation can be explained by the presence of both bound and unbound CT states in the same film, as a result of a range of interface structures.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Spectroscopic Investigation of the Effect of Microstructure and Energetic Offset on the Nature of Interfacial Charge Transfer States in Polymer: Fullerene Blends

Dimitrov

Azzouzi

et al. 2019

J. Am. Chem. Soc.

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“…Some flavonoids have a selective DNMTs inhibitory activity, for example kaempferol inhibits DNMT1 and DNMT3B but not DNMT3A 0 enzymatic activity in bladder and CRC cancer (Banerji 2017;Lu et al 2018).…”

Section: Phytochemicals Modulating the Epigenetic Alterations Of Dna mentioning

confidence: 99%

Phytochemicals in cancer prevention: modulating epigenetic alterations of DNA methylation

Pop

Enciu

Tarcomnicu³

et al. 2019

Phytochem Rev

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Cancer can take many years to develop from initiation to progression. The long period of development might represent an opportunity to use multi-functional, multi-targeted preventive drugs to block or reverse tumorigenesis. One path to cancer prevention could be to target and reverse the early epigenetic alterations. Unlike genetic mutations, they are potentially reversible and can be restored to their normal state. Epidemiological studies have revealed the close link between rich diets in bioactive compounds and the low incidence of different types of cancer. Thus, the study regarding the impact of bioactive nutrients on the epigenome has become widespread, with focus on the modulation of epigenetic mechanisms of gene expression, such as genomic DNA methylation. Following altered activity and expression of DNA methyl transferases and ten-eleven translocation enzymes, different types of cancers exert local DNA hypermethylation of gene promoters of tumor suppressor genes or of non-coding RNAs (microRNAs and long-noncoding RNAs), as well as global hypomethylation. Recently, the potential of phytochemicals to modulate epigenetic events in human health has become evident, although specific molecular mechanisms are still unclear. Phytochemicals and other bioactive dietary compounds can restore global and gene-specific promoter DNA methylation patterns by reactivating DNA methyltransferases or by providing the provision of methyl groups. Several natural products, such as EGCG, curcumin, sulforaphane, have shown DNMT inhibitory activity, but this property needs more in-depth investigations. This review focuses on the impact of modified DNA methylation pattern on early carcinogenesis and summarizes the effects/mechanism of phytochemical interventions on this type of epigenetic alterations.

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“…Organic photovoltaic (OPV) devices have been leading the research into energy science and technology. [1][2][3] In recent years, much attention has been devoted to the perovskite materials and their applications in solar energy conversion because of their high absorbance, low carrier recombination rate, outstanding ferroelectric properties and easier synthesis. [4][5][6] Among them, perovskite solar cells (PSC) with CH 3 NH 3 PbX 3 perovskites (X ¼ Cl, Pb, and I) as absorber layers show great potential in fabricating low-cost and large-scale commercial solar cells, whose efficiency has increased from 3.8% to over 22% in the past ve years.…”

Section: Introductionmentioning

confidence: 99%