Organic−inorganic perovskite

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Improving the heterointerface in hybrid organic–inorganic perovskite solar cells by surface engineering: Insights from periodic hybrid density functional theory calculations

Improving the heterointerface in hybrid organic–inorganic perovskite solar cells by surface engineering: Insights from periodic hybrid density functional theory calculations

A periodic hybrid density functional theory computational strategy is presented to model the heterointerface between the methylammonium lead iodide (MAPI) perovskite and titanium dioxide (TiO 2 ), as found in perovskite solar cells (PSC), where the 4-chlorobenzoic acid (CBA) ligand is used to improve the stability and the band alignment at the interface. The CBA ligand acts as a bifunctional linker to efficiently connect the perovskite and the oxide moieties, ensuring the stability of the interface through Ti-O and Pb-Cl interactions. The computed density of states reveals that the perovskite contributes to the top of the valence band while the oxide contributes to the bottom of the conduction band with a direct bandgap of 2.16 eV, indicating a possible electron transfer from MAPI to TiO 2 . Dipole moment
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Improving the heterointerface in hybrid organic–inorganic perovskite solar cells by surface engineering: Insights from periodic hybrid density functional theory calculations

Improving the heterointerface in hybrid organic–inorganic perovskite solar cells by surface engineering: Insights from periodic hybrid density functional theory calculations

These perovskites are composed of an organic cation A, a divalent metal cation M generally belonging to the fourth main group and a halide anion X, which are arranged in a rigid three- dimensional network of corner-sharing MX 6 octohedra. By varying the different possible combinations between these cationic and anionic species, bandgap tuning of the perovskite material is possible, thus allowing to readily modulate its light absorption for photovoltaic application. Although the M and X species can in principle be easily tuned in these structures, the A cation on the other hand fills the 12-fold coordinated cubo-octahedral space created by the inorganic metal halide octahedra, hence making its choice limited to either monovalent cations such as Cs + , Rb + or K + , or to the small organic methylammonium (MA + ) and
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Electron irradiation induced aging effects on radiative recombination properties of quadruple cation organic-inorganic perovskite layers

Electron irradiation induced aging effects on radiative recombination properties of quadruple cation organic-inorganic perovskite layers

Keywords Quadruple-cation hybrid perovskites . Defects . Electron irradiation . Photoluminescence . Aging effects 1 Introduction Due to their unique optoelectronic properties (high absorption coefficient in the visible range, long charge carrier lifetime, high carrier mobility) and their simple processability through both solution and gas phase techniques, the hybrid organic inorganic halide perovskites (HOIPs) have witnessed a semi- nal growth in their photovoltaic efficiencies reaching the per- formance of standard semiconductors like silicon [ 1 ]. Although a large body of data has become available on perovskite-based photovoltaic devices mostly based on com- positional variations (isoelectronic substitutions), the perov- skite technology suffers from a number of stress factors, such as instability of HOIPs under illumination (both solar and UV), atmospheric conditions (moisture and oxygen), and in- terfacial reactions (ion migration), which deteriorate their de- vice performance and efficiency. In this context, the role of native vacancy defects has been discussed as a possible cause for solar cell degradation, carrier lifetime reduction as well as for the hysteresis in the current-voltage curve under illumina- tion. Defect-related trap states can act as nonradiative
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Theoretical studies of Rashba and Dresselhaus effects in hybrid organic-inorganic perovskites for optoelectronic applications

Theoretical studies of Rashba and Dresselhaus effects in hybrid organic-inorganic perovskites for optoelectronic applications

[7] Chondroudis, K., Mitzi, D. B., “Electroluminescence from an OrganicInorganic Perovskite Incorporating a Quaterthiophene Dye within Lead Halide Perovskite Layers,” Chem. Mater. 11(11), 3028–3030 (1999). [8] Even, J., Pedesseau, L., Dupertuis, M.-A., Jancu, J.-M., Katan, C., “Electronic model for self-assembled hybrid organic/perovskite semiconductors: Reverse band edge electronic states ordering and spin-orbit coupling,” Phys. Rev. B 86(20) (2012).

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Anharmonicity in Hybrid and Inorganic Perovskite Materials used for Photovoltaics Applications References

Anharmonicity in Hybrid and Inorganic Perovskite Materials used for Photovoltaics Applications References

arthur.marronnier@polytechnique.edu Hybrid organic-inorganic perovskite materials have emerged over the past five years as absorber layers for new high-efficiency yet low-cost solar cells that combine the advantages of organic and inorganic semiconductors. Despite this sky rocketing evolution, the physics behind the electronic transport in these materials is still poorly understood.

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Rashba and Dresselhaus Effects in Hybrid Organic-Inorganic Perovskites: From Basics to Devices

Rashba and Dresselhaus Effects in Hybrid Organic-Inorganic Perovskites: From Basics to Devices

pounds we find Rashba parameters of nearly 1 eV.Å, proving that despite the important distortions caused by the organic cation, the SOC effect prevails. By means of a 2D non-centrosymmetric structure, we show how the amplitude of the splitting can be monitored with temperature, as a result of the continuous polarization of the crystal structure from high to low temperatures. Finally we inspect the case of centrosymmetric structure exhibiting a Rashba spin splitting under the in- fluence of a transverse electric field. The possibility to control the spin precession in the material thanks to a gate voltage constitutes the base for a hybrid organic-inorganic perovskite-based spin FET.
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Electronic properties of 2D and 3D hybrid organic/inorganic perovskites for optoelectronic and photovoltaic applications

Electronic properties of 2D and 3D hybrid organic/inorganic perovskites for optoelectronic and photovoltaic applications

3 CNRS, Institut des Sciences Chimiques de Rennes, UMR 6226, 35042 Rennes, France (*author for correspondence: E-mail: laurent.pedesseau@insa-rennes.fr) Abstract. We herein investigate theoretically both 2D and 3D Hybrid Organic/inorganic Perovskite (HOP) crystal structures based on Density Functional Theory (DFT) calculations and symmetry analyses. Our findings reveal the universal features of the electronic band structure for the class of lead-halide hybrids (R-NH 3 ) n PbX m , where (n,m)=(2,4) and (1,3) respectively for 2D and 3D structures. Among those, the large spin-orbit
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Viral ecology of organic and inorganic particles in aquatic systems: avenues for further research

Viral ecology of organic and inorganic particles in aquatic systems: avenues for further research

The microbial ecology of organic aggregates in marine and limnetic systems appears to be rather well understood, and the major processes forming and decomposing aggregates have been identified and studied in detail (Simon et al. 2002). Aggregate- associated processes have also been included in food web and biogeochemical models of pelagic systems (Jackson 2001). To incorporate viruses into such mod- els, specific data have to be obtained: (1) quantifica- tion of specific pools, such as viral abundance and the frequency of infected and lysogenic cells; (2) quantifi- cation of rates of viral production, viral decay, virus- mediated host mortality and the release of carbon and other elements due to viral lysis; and (3) pro- cesses have to be better constrained, such as the effect of viruses on aggregate formation and dissolu- tion and aggregate buoyancy and quality. Method- ological progress or refinement will thus be neces- sary. Major differences in the way organic aggregates and associated microorganisms are involved in the dynamics of nutrients, DOM and POM exist between pelagic marine and limnetic systems with rather weak hydrodynamic forcing, and shallow and turbid marine, estuarine, riverine and lacustrine systems with strong and highly variable hydrodynamic forc- ing (Simon et al. 2002). To determine whether or not viral impacts also differ between these 2 general types of systems will be a challenge for years to come. Our understanding of species and the func- tional diversity of aquatic viruses and microorganisms has made a leap forward by methodological progress. This allows researchers to link studies on diversity with those on ecosystem function and biogeochemical cycles, and is also applicable to the study of virus–aggregate interactions. The application of mol- ecular tools will help assess the biodiversity of attached viral communities and the potential for spe- cific adaptations of viral types for existence on aggre- gates. Such information can then be scaled up to assess the role of virus–aggregate interactions in microbial biodiversity, ecosystem functioning and bio- geochemical cycles.
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Nanofiltration of solutions containing organic and inorganic salts: Relationship between feed and permeate proportions

Nanofiltration of solutions containing organic and inorganic salts: Relationship between feed and permeate proportions

The current results are in agreement with previous ones. Indeed, for solutions containing monovalent and divalent organic acid salts of various molecular weights (formate, acetate, lactate, and succinate) it was also reported that the retention of the most retained solute, succi- nate, was higher in the binary mixtures than in the single solutions. Meanwhile, the retentions of the less retained acid salts, formate, ace- tate, and lactate, decreased significantly in the presence of succinate and even reached negative values under certain conditions. The extent of decline of monovalent acid salt retentions followed the sequence: formate > acetate > lactate [ 23 ]. This trend, i.e. increase of the reten- tion of the more retained solute and decrease of the less retained solute, was mentioned as “distribution effect” [ 23 ] or “co-ions competition” [ 33 , 34 ]. The mechanisms involved in co-ions interactions were comprehensively discussed via investigation of the negative retention phenomenon [ 24 ]. For a system with one counter-ion and two co-ions of different mobilities, the electrokinetic charge density is zero. The more mobile co-ions are electrostatically attracted to the membrane phase to compensate for the potential deviations from electric neutrality arising due to the strong exclusion of the less mobile co-ions. Therefore, a decrease in the retention of more mobile co-ions is observed. This phe- nomenon is a general feature for mixed solutions with less and more retained ions using charged or uncharged membranes [ 24 ].The con- centration ratio between the ions was suggested as one of the major
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Biodegradable and biocompatible inorganic-organic hybrid materials. 2. Dynamic mechanical properties, structure and morphology

Biodegradable and biocompatible inorganic-organic hybrid materials. 2. Dynamic mechanical properties, structure and morphology

stiffer inorganic material for the organic polyester. Also, expectedly, the magnitude of the tan δ peak characteristic of the PCL glass transition rapidly decreases and tends to become broader and shifted toward higher temperature when the PCL content is decreased from 20 to 10 wt.% (Figure 5). When 5 wt.% PCL are used, the peak is too weak for reliable conclusions to be drawn. It would thus appear that when the content of the stiff component (silica) is increased, the restrictions imposed on the flexible PCL chains are also more severe consistently with an intimate mixing of the two components. Nevertheless, the transition at ca. -80 ° C is still visible when T g of PCL is no longer observed in the tan 8 versus temperature curve, which might indicate that
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Total organic and inorganic carbon exchange through the Strait of Gibraltar in September 1997

Total organic and inorganic carbon exchange through the Strait of Gibraltar in September 1997

Intercalibration exercises in 1995, organized by Dr. J.H. Sharp, indicated that our instrument was suitable for marine DOC studies. 3.3. Total inorganic carbon Total inorganic carbon (C ") was computed from experimental values of pH" and total alkalinity, the carbonic acid dissociation constants of Roy et al. (1993), and the boric acid dissociation constant of Dickson (1990). Several authors have examined the thermodynamic consistency of the measured components of the carbonate system (e.g., Millero et al., 1993; Clayton et al., 1995; Lee et al., 1997; McElligott et al., 1998). From these studies it appears that at present it is not possible to draw a "rm conclusion regarding the best set of constants to use. Considering the accuracy of photometric pH ($0.002) and potentiometric total alkalinity ($1 !mol kg#$) determinations (Mintrop et al., 1999), Lee et al. (1997) estimated that the probable errors in C " determined with the Roy et al. (1993) constants is around 4 !mol kg#$. This is slightly higher than the accuracy of the experimental value ($2 !mol kg#$, Johnson et al., 1993). Recent determinations of pH ", A " and C " in the Azores area have shown internal consistency among these paramenters. C" measured was only, on average, 0.54 !mol kg#$ higher than C" calculated, with a standard deviation of $2.6 !mol kg#$, when the Roy et al. (1993) constants were used (Mintrop and GonzaHlez-DaHvila, unpublished observations).
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Narrow Linewidth Excitonic Emission in Organic-Inorganic Lead Iodide Perovskite Single Crystals

Narrow Linewidth Excitonic Emission in Organic-Inorganic Lead Iodide Perovskite Single Crystals

value corresponds roughly to the FE-LE en- ergy separation. Above 50K, the FE emission quenches in turn with an activation energy of Ea = 28.4 ± 0.6 meV. The latter process is mainly connected to the dissociation of the ex- citon and the energy gives a rough estimation of the binding energy of the free exciton in the low temperature orthorhombic phase. However, we note that apart from the inuence of the LE emitting states, additional non-radiative, ther- mal quenching processes may also exist and are not taking into account here. This estima- tion of the binding energy in the low temper- ature phase is in good agreement with recent measurements based on the tting of the thin lms absorption spectrum with Elliott's formu- las (15-30 meV). 20,23,27,51 Nicholas and cowork- ers use a more direct method relying on mag- netoabsorption spectroscopy of thin lms and report a binding energy of 16 meV in the or- thorhombic phase. 22 We remark that the ma- jority of studies on the excitonic binding en- ergy focused on thin lms properties. However, Petrozza and coworkers have observed that the excitonic resonance depends on the crys- tallinity of the material and suggest that the degree of order-disorder of the organic cation may have an impact on exciton binding en- ergy. 13,15 Hence, polycrystalline thin lms, with microscale grain size, and large bulk monocrys- talline domains may present dierent excitonic properties. 29 Study of the absorption spectra of single crystals under high magnetic eld would be fruitful to clarify this point.
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Anharmonicity and Disorder in the Black Phases of Cesium Lead Iodide used for Stable Inorganic Perovskite Solar Cells

Anharmonicity and Disorder in the Black Phases of Cesium Lead Iodide used for Stable Inorganic Perovskite Solar Cells

3 . 17,19,20 More recently, some of us investigated the temperature dependence of CsP bI 3 ’s band gap and how reversible the non-perovskite to perovskite structural transformations at high temperature 21 can be. It was shown that, after heating the samples above 360 ◦ C, the room temperature δ-phase (yellow) converts to the black perovskite α-phase . At variance, during the cooling step, the perovskite structure converts at 260 ◦ C to the β-phase and at 175 ◦ C to the γ-phase; both these phases are black. Only after a few days the yellow δ-phase is obtained again. This work was the first report on the black orthorhombic γ-phase that is crucial in the context of photovoltaics applications.
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Near-infrared inorganic/organic optical upconverter with an external power efficiency of>100%

Near-infrared inorganic/organic optical upconverter with an external power efficiency of>100%

Figure 2 . (a) Schematic cross section of hybrid optical upconverter device with integrated InGaAs/InP HPT and OLED. Note that the thickness of the organic and inorganic layers is not to scale. The embedded mirror layer consists of 20-nm Ti and 100-nm Au. The hole injection layer (HIL) of the OLED was a 3-nm thick layer of fullerene (C 60 ). The hole transport layers (HTLs) consisted of copper phthalocyanine (CuPc) (25 nm) and N,N ′ -diphenyl-N,N ′ - bis-(1-naphthyl)-1–1 ′ -biphenyl-4,4 ′ -diamine ( α -NPD) (45 nm). The 30 nm thick emission zone was tris-(8-hydroxyquinoline) aluminum (Alq 3 ), doped
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Modelling iodide ? iodate speciation in atmospheric aerosol: Contributions of inorganic and organic iodine chemistry

Modelling iodide ? iodate speciation in atmospheric aerosol: Contributions of inorganic and organic iodine chemistry

most important precursor of aerosol iodate, is quite uncer- tain, both regarding its formation pathways and the respec- tive reactions rates. Third, the current knowledge about at- mospheric organic iodine chemistry is poor, very little quali- tative and almost no quantitative information is available yet. The existence of organic forms of iodine as inferred by Baker (2005) has to be reconfirmed in further measurements and its consequences for chemistry in general and iodine speciation in particular have to be investigated. In this context, also the fate of freshly nucleated iodine particles would be interesting as these could, if growing or being taken up by other particles also affect iodine speciation in atmospheric aerosol.
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Experimental and theoretical studies of NLO properties of organic–inorganic materials base on p-nitroaniline

Experimental and theoretical studies of NLO properties of organic–inorganic materials base on p-nitroaniline

Third order nonlinear optical properties of a serie of chromophores were investigated using nonlinear transmission (NLT), degenerate four waves mixing (DFWM) and third harmonic generat[r]

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Mechanistic Investigation of a Dual Bicyclic Photoinitiating System for Synthesis of Organic–Inorganic Hybrid Materials

Mechanistic Investigation of a Dual Bicyclic Photoinitiating System for Synthesis of Organic–Inorganic Hybrid Materials

(1.2  10 9 and 10 6 M -1 .s -1 respectively). Application of dual bicyclic initiating system for synthesis of organic-inorganic material The ability of the bicyclic system to generate initiating radicals and protons simultaneously can be employed to perform simultaneously a free radical photopolymerization (FRP) and a photoacid catalyzed sol-gel reaction (PSG) under LED at 395 nm. A difunctional methacrylate monomer (SR348C) was selected for attesting radical initiation of organic polymerization and a poly(dimethoxysiloxane) sol-gel precursor (PDMOS) was used for proton-catalyzed photoinduced sol-gel process (Chart 1).
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Composite RNAi-Microsponges Form through Self-Assembly of the Organic and Inorganic Products of Transcription

Composite RNAi-Microsponges Form through Self-Assembly of the Organic and Inorganic Products of Transcription

In addition to its utility for signal amplification and detection, RCR also provides a simple and unique approach for synthesizing large, periodic nucleic acids with interesting properties. By designing appropriate templates, the concatemeric DNA or RNA obtained by RCR can be made to contain high densities of functional units, such as ribozymes, shRNA, and aptamers.[12-15] Recently, researchers have also begun investigating the self-assembly of nucleic acids produced by RCR into diverse nanostructures.[16-21] This has been achieved through different approaches that often employ the rolling circle product as a structural scaffold for other materials, such as complementary nucleic acids, peptides, and inorganic nanoparticles. These exciting applications of RCR could lead to new routes for designing programmable materials with both inherent biological activity and unique structural properties.
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Novel organic−inorganic hybrids with increased water retention for elevated temperature proton exchange membrane application

Novel organic−inorganic hybrids with increased water retention for elevated temperature proton exchange membrane application

Dynamic Mechanical Analysis. DMA was used to determine the cluster relaxation T c and the influence of inorganic content on the mechanical strength of the mem- brane. The tan δ curves for the hybrid membranes and Nafion are shown in Figure 6. For all the membranes the ionic cluster transition T c was obtained from the peak of the tan delta (δ) curve. Nafion has a T c of 116.8 ° C, and it can be seen that the T c s of all hybrid membranes are very broad and shift to higher temperatures. It is widely known that above 115 ° C the network of hydrophilic clusters, made up from sulfonic groups, is becoming extremely mobile before the clustered structure finally collapses. 44 This can be due to either loss of water under dry and hot conditions or further uptake of solvents if exposed to saturated solvent/water vapor. This high mobility of the backbone and cluster network is shown by a higher value of loss tangent for unmodified Nafion in comparison to hybrid membranes. Further, we see that the T c increases for the hybrid membranes, which implies that they are thermomechanically more stable than unmodified Nafion membrane. This increase in T c results in a decrease in the free volume of Nafion, which is also seen by a lower water uptake of the hybrids by TGA of swollen membranes. For hybrids 2, 3, and 4 the onset of the T c peak starts at 150, 130, and 140 ° C, respectively. Incorporation of particles within the membrane has formed strong interaction between the inorganic component and polymer matrix and increases rigidity in the membrane. However, the T c of the hybrid membranes appears to be very broad over a higher temper- ature range. This indicates that the segmental mobility in hybrid membranes occurs over a very broad temperature range. The hybrid membranes thus become more stable in nature and can withstand higher temperatures due to the presence of the inorganic additives within the pores of unmodified Nafion 117. 15 These results are also in agreement with the TGA results, which show an increase in the degradation temperatures for the hybrid membranes.
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Nanofiltration of solutions containing organic and inorganic salts: Relationship between feed and permeate proportions

Nanofiltration of solutions containing organic and inorganic salts: Relationship between feed and permeate proportions

The current results are in agreement with previous ones. Indeed, for solutions containing monovalent and divalent organic acid salts of various molecular weights (formate, acetate, lactate, and succinate) it was also reported that the retention of the most retained solute, succi- nate, was higher in the binary mixtures than in the single solutions. Meanwhile, the retentions of the less retained acid salts, formate, ace- tate, and lactate, decreased significantly in the presence of succinate and even reached negative values under certain conditions. The extent of decline of monovalent acid salt retentions followed the sequence: formate > acetate > lactate [ 23 ]. This trend, i.e. increase of the reten- tion of the more retained solute and decrease of the less retained solute, was mentioned as “distribution effect” [ 23 ] or “co-ions competition” [ 33 , 34 ]. The mechanisms involved in co-ions interactions were comprehensively discussed via investigation of the negative retention phenomenon [ 24 ]. For a system with one counter-ion and two co-ions of different mobilities, the electrokinetic charge density is zero. The more mobile co-ions are electrostatically attracted to the membrane phase to compensate for the potential deviations from electric neutrality arising due to the strong exclusion of the less mobile co-ions. Therefore, a decrease in the retention of more mobile co-ions is observed. This phe- nomenon is a general feature for mixed solutions with less and more retained ions using charged or uncharged membranes [ 24 ].The con- centration ratio between the ions was suggested as one of the major
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