scholarly journals The remarkable influence of M2δ to thienyl π conjugation in oligothiophenes incorporating MM quadruple bonds

2008 ◽  
Vol 105 (40) ◽  
pp. 15247-15252 ◽  
Author(s):  
G. T. Burdzinski ◽  
M. H. Chisholm ◽  
P.-T. Chou ◽  
Y.-H. Chou ◽  
F. Feil ◽  
...  
Keyword(s):  
Thin Films ◽  
Carboxylic Acid ◽  
Energy Gap ◽  
Photophysical Properties ◽  
Visible Region ◽  
Triplet States ◽  
Relaxation Dynamics ◽  
Dual Emission ◽  
Molybdenum Complexes ◽  
Quadruple Bonds

Oligothiophenes incorporating MM quadruple bonds have been prepared from the reactions between Mo2(TiPB)4 (TiPB = 2,4,6-triisopropyl benzoate) and 3′,4′-dihexyl-2,2′-:5′,2″-terthiophene-5,5″-dicarboxylic acid. The oligomers of empirical formula Mo2(TiPB)2(O2C(Th)-C4(n-hexyl)2S-(Th)CO2) are soluble in THF and form thin films with spin-coating (Th = thiophene). The reactions between Mo2(TiPB)4 and 2-thienylcarboxylic acid (Th-H), 2,2′-bithiophene-5-carboxylic acid (BTh-H), and (2,2′:5′,2″-terthiophene)-5-carboxylic acid (TTh-H) yield compounds of formula trans-Mo2(TiPB)2L2, where L = Th, BTh, and TTh (the corresponding thienylcarboxylate), and these compounds are considered as models for the aforementioned oligomers. In all cases, the thienyl groups are substituted or coupled at the 2,5 positions. Based on the x-ray analysis, the molecular structure of trans-Mo2(TiPB)2(BTh)2 reveals an extended Lπ-M2δ-Lπ conjugation. Calculations of the electronic structures on model compounds, in which the TiPB are substituted by formate ligands, reveal that the HOMO is mainly attributed to the M2δ orbital, which is stabilized by back-bonding to one of the thienylcarboxylate π* combinations, and the LUMO is an in-phase combination of the thienylcarboxylate π* orbitals. The compounds and the oligomers are intensely colored due to M2δ–thienyl carboxylate π* charge transfer transitions that fall in the visible region of the spectrum. For the molybdenum complexes and their oligomers, the photophysical properties have been studied by steady-state absorption spectroscopy and emission spectroscopy, together with time-resolved emission and transient absorption for the determination of relaxation dynamics. Remarkably, THF solutions the molybdenum complexes show room-temperature dual emission, fluorescence and phosphorescence, originating mainly from 1MLCT and 3MM(δδ*) states, respectively. With increasing number of thienyl rings from 1 to 3, the observed lifetimes of the 1MLCT state increase from 4 to 12 ps, while the phosphorescence lifetimes are ≈80 μs. The oligomers show similar photophysical properties as the corresponding monomers in THF but have notably longer-lived triplet states, ≈200 μs in thin films. These results, when compared with metallated oligothiophenes of the later transition elements, reveal that M2δ–thienyl π conjugation leads to a very small energy gap between the 1MLCT and 3MLCT states of <0.6 eV.

scholarly journals Photocatalysis Goes Thinner Than a Hair: Carbon Nitride Thin Films as All-in-one Technology for Photocatalysis

2021 ◽  
Author(s):  
Stefano Mazzanti ◽  
Giovanni Manfredi ◽  
Alex J. Barker ◽  
Markus Antonietti ◽  
Aleksandr Savateev ◽  
...  
Keyword(s):  
Thin Films ◽  
Carbon Nitride ◽  
Energy Gap ◽  
Morphological Changes ◽  
Photophysical Properties ◽  
Chemical Vapor ◽  
Triplet Energy ◽  
Photocatalytic Reactions ◽  
Area Unit ◽  
Triplet Excited States

Organic π-conjugated polymers are promising heterogeneous photocatalysts that involve photoredox or energy transfer processes. In such settings, the materials are usually applied in the form of a dispersion in liquid medium, which is bound to certain technological limits of applicability. Herein, we present an innovative approach using carbon nitride thin films prepared via chemical vapor deposition (CVD) at different vessel walls and using them as batch and microfluidic photoreactors. This approach allows not only to fabricate technologically relevant and reusable devices, also photophysical properties of carbon nitride, such as singlet-triplet energy gap and lifetime of triplet excited states, are improved, when the material is assembled in thin films. These morphological changes are employed to maximize performance of the materials in photocatalytic reactions, in which the carbon nitride thin films show at least one orders of magnitude higher activity per area unit compared to photocatalysis using suspended particles.<br>

scholarly journals Photophysical Properties of Nitrated and Halogenated Phosphorus Tritolylcorrole Complexes: Insights from Theory

Molecules ◽  
2018 ◽  
Vol 23 (11) ◽  
pp. 2779 ◽  
Author(s):  
Marta Alberto ◽  
Bruna De Simone ◽  
Gloria Mazzone ◽  
Nino Russo ◽  
Marirosa Toscano
Keyword(s):  
Excited States ◽  
Density Functional ◽  
Energy Gap ◽  
Photophysical Properties ◽  
Intersystem Crossing ◽  
Triplet States ◽  
Excited Singlet ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Singlet And Triplet States

The photophysical properties of a series of nitrated and halogenated phosphorus tritolylcorrole complexes were studied in dichloromethane solvent by using the density functional theory. Particular emphasis was given to the absorption spectra, the energy gap between the excited singlet and triplet states, and the magnitude of the spin-orbit couplings for a series of possible intersystem crossing channels between those excited states. The proposed study provides a better description of the photophysical properties of these systems while giving insights into their possible use as photosensitizers in photodynamic therapy.

scholarly journals Study on the Physical Properties of Pulsed Laser Deposited Doped Copper Oxide (Cu2 O) Thin Films for Optical Device Applications

2020 ◽  
pp. 1-6
Author(s):  
Gurpreet Kaur ◽  
◽  
Anirban Mitra ◽  
Keyword(s):  
Thin Films ◽  
Absorption Coefficient ◽  
Room Temperature ◽  
Energy Gap ◽  
Visible Region ◽  
Pulsed Laser ◽  
Practical Applications ◽  
Wide Range ◽  
Cu2o Films ◽  
Cu2o Thin Films

Cuprous oxide, (Cu2O) is a promising p-type semiconductor, finds practical applications in a wide range of optoelectronic devices. In this paper, pulsed laser deposition technique is employed to deposit doped Cu2O thin films. The influence of doping of silver (Ag), aluminium (Al) and co-doping of (Ag+Al) in Cu2O thin films is illustrated. X-ray diffraction pattern depicts cubic crystal structure and polycrystalline nature of grown thin films, having small crystallite size (~50 nm). Atomic force microscopy (AFM) obtained surface images of the films portrait uniform grain morphology with low surface roughness. The room temperature optical characterizations of the thin films, the transmittance versus wavelength in the UV-Visible region exhibits low transmission values upto 10–20%, illustrates the large absorption coefficient (α), numerical values varying from 104 to 105cm-1 for doped Cu2O films. The large values of absorption coefficient facilitate the optical and photovoltaic applications of the doped Cu2O films. The addition of dopant species Ag and Al, the optical band gap is increased and it varies in the range of 2.65−2.84 eV. The increased energy gap is attributed to the substitution of Al and Ag ions for the oxygen ions reduce the width of valence band to widen the energy gap. The I−V characteristics plot obtained at room temperature indicates low electrical resistivity (ρ ~ 10-2Ω- cm) of the films. The obtained results are of high relevance and indicate potential applications of the grown thin films in semiconductor devices such as solar cells, photodetectors and optical sources

scholarly journals Photocatalysis Goes Thinner Than a Hair: Carbon Nitride Thin Films as All-in-one Technology for Photocatalysis

2021 ◽  
Author(s):  
Stefano Mazzanti ◽  
Giovanni Manfredi ◽  
Alex J. Barker ◽  
Markus Antonietti ◽  
Aleksandr Savateev ◽  
...  
Keyword(s):  
Thin Films ◽  
Carbon Nitride ◽  
Energy Gap ◽  
Morphological Changes ◽  
Photophysical Properties ◽  
Chemical Vapor ◽  
Triplet Energy ◽  
Photocatalytic Reactions ◽  
Area Unit ◽  
Triplet Excited States

Organic π-conjugated polymers are promising heterogeneous photocatalysts that involve photoredox or energy transfer processes. In such settings, the materials are usually applied in the form of a dispersion in liquid medium, which is bound to certain technological limits of applicability. Herein, we present an innovative approach using carbon nitride thin films prepared via chemical vapor deposition (CVD) at different vessel walls and using them as batch and microfluidic photoreactors. This approach allows not only to fabricate technologically relevant and reusable devices, also photophysical properties of carbon nitride, such as singlet-triplet energy gap and lifetime of triplet excited states, are improved, when the material is assembled in thin films. These morphological changes are employed to maximize performance of the materials in photocatalytic reactions, in which the carbon nitride thin films show at least one orders of magnitude higher activity per area unit compared to photocatalysis using suspended particles.<br>

scholarly journals The Photophysical Properties of Triisopropylsilyl-ethynylpentacene—A Molecule with an Unusually Large Singlet-Triplet Energy Gap—In Solution and Solid Phases

Chemistry ◽  
2020 ◽  
Vol 2 (2) ◽  
pp. 545-564
Author(s):  
Fabio A. Schaberle ◽  
Carlos Serpa ◽  
Luis G. Arnaut ◽  
Andrew D. Ward ◽  
Joshua K. G. Karlsson ◽  
...  
Keyword(s):  
Energy Gap ◽  
Photophysical Properties ◽  
Solute Concentration ◽  
Fluorescence Yield ◽  
Triplet States ◽  
Dilute Solution ◽  
Excimer Emission ◽  
Triplet Energy ◽  
Time Resolved ◽  
Singlet Exciton

The process of singlet-exciton fission (SEF) has attracted much attention of late. One of the most popular SEF compounds is TIPS-pentacene (TIPS-P, where TIPS = triisopropylsilylethynyl) but, despite its extensive use as both a reference and building block, its photophysical properties are not so well established. In particular, the triplet state excitation energy remains uncertain. Here, we report quantitative data and spectral characterization for excited-singlet and -triplet states in dilute solution. The triplet energy is determined to be 7940 ± 1200 cm−1 on the basis of sensitization studies using time-resolved photoacoustic calorimetry. The triplet quantum yield at the limit of low concentration and low laser intensity is only ca. 1%. Self-quenching occurs at high solute concentration where the fluorescence yield and lifetime decrease markedly relative to dilute solution but we were unable to detect excimer emission by steady-state spectroscopy. Short-lived fluorescence, free from excimer emission or phosphorescence, occurs for crystals of TIPS-P, most likely from amorphous domains.

Formation of high temperature phase in flash-evaporated SnSe films

1990 ◽  
Vol 48 (4) ◽  
pp. 698-699
Author(s):  
J.P.S. Hanjra
Keyword(s):  
Thin Films ◽  
Electrical Properties ◽  
Energy Gap ◽  
Dominant Role ◽  
Fine Powder ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
Water Mixture ◽  
Flash Evaporation ◽  
Photovoltaic Applications

Tin mono selenide (SnSe) with an energy gap of about 1 eV is a potential material for photovoltaic applications. Various authors have studied the structure, electronic and photoelectronic properties of thin films of SnSe grown by various deposition techniques. However, for practical photovoltaic junctions the electrical properties of SnSe films need improvement. We have carried out investigations into the properties of flash evaporated SnSe films. In this paper we report our results on the structure, which plays a dominant role on the electrical properties of thin films by TEM, SEM, and electron diffraction (ED).Thin films of SnSe were deposited by flash evaporation of SnSe fine powder prepared from high purity Sn and Se, onto glass, mica and KCl substrates in a vacuum of 2Ø micro Torr. A 15% HF + 2Ø% HNO3 solution was used to detach SnSe film from the glass and mica substrates whereas the film deposited on KCl substrate was floated over an ethanol water mixture by dissolution of KCl. The floating films were picked up on the grids for their EM analysis.

scholarly journals 7-Alkoxy-appended coumarin derivatives: synthesis, photo-physical properties, aggregation behaviours and current–voltage (I–V) characteristic studies on thin films

RSC Advances ◽  
2021 ◽  
Vol 11 (17) ◽  
pp. 10212-10223
Author(s):  
Abhijit Rudra Paul ◽  
Bapi Dey ◽  
Sudip Suklabaidya ◽  
Syed Arshad Hussain ◽  
Swapan Majumdar
Keyword(s):  
Thin Films ◽  
Carboxylic Acid ◽  
Physical Properties ◽  
Chemical Characteristics ◽  
Coumarin Derivatives ◽  
Design Synthesis ◽  
Electrical Switching ◽  
Physico Chemical ◽  
Current Voltage

In this article, we demonstrate the design, synthesis and physico-chemical characteristics, including electrical switching behaviours of long alkoxy-appended coumarin carboxylate/carboxylic acid in thin films.

scholarly journals The Photostability of Novel Boron Hydride Blue Emitters in Solution and Polystyrene Matrix

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 589
Author(s):  
Jakub Ševčík ◽  
Pavel Urbánek ◽  
Barbora Hanulíková ◽  
Tereza Čapková ◽  
Michal Urbánek ◽  
...  
Keyword(s):  
Thin Films ◽  
Photophysical Properties ◽  
Inorganic Compounds ◽  
Solid Polymer ◽  
Organic Polymer ◽  
Quantum Yields ◽  
Boron Hydride ◽  
Polystyrene Matrix ◽  
Blue Emitters ◽  
Solvent Blends

In recent work, the boron hydride anti-B18H22 was announced in the literature as a new laser dye, and, along with several of its derivatives, its solutions are capable of delivering blue luminescence with quantum yields of unity. However, as a dopant in solid polymer films, its luminescent efficiencies reduce dramatically. Clarification of underlying detrimental effects is crucial for any application and, thus, this contribution makes the initial steps in the use of these inorganic compounds in electrooptical devices based on organic polymer thin films. The photoluminescence behavior of the highly luminescent boron hydrides, anti-B18H22 and 3,3′,4,4′-Et4-anti-B18H18, were therefore investigated. The quantum yields of luminescence and photostabilities of both compounds were studied in different solvents and as polymer-solvent blends. The photophysical properties of both boranes are evaluated and discussed in terms of their solvent-solute interactions using photoluminescence (PL) and NMR spectroscopies. The UV degradability of prepared thin films was studied by fluorimetric measurement. The effect of the surrounding atmosphere, dopant concentration and the molecular structure were assessed.

scholarly journals Synthesis, Crystallography, Microstructure, Crystal Defects, Optical and Optoelectronic Properties of ZnO:CeO2 Mixed Oxide Thin Films

Photonics ◽  
2020 ◽  
Vol 7 (4) ◽  
pp. 112
Author(s):  
Qais M. Al-Bataineh ◽  
Mahmoud Telfah ◽  
Ahmad A. Ahmad ◽  
Ahmad M. Alsaad ◽  
Issam A. Qattan ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Refractive Index ◽  
Mixed Oxide ◽  
Visible Region ◽  
Functional Materials ◽  
Crystal Defects ◽  
Optoelectronic Properties ◽  
Oxide Thin Films ◽  
Pure Ceo2

We report the synthesis and characterization of pure ZnO, pure CeO2, and ZnO:CeO2 mixed oxide thin films dip-coated on glass substrates using a sol-gel technique. The structural properties of as-prepared thin film are investigated using the XRD technique. In particular, pure ZnO thin film is found to exhibit a hexagonal structure, while pure CeO2 thin film is found to exhibit a fluorite cubic structure. The diffraction patterns also show the formation of mixed oxide materials containing well-dispersed phases of semi-crystalline nature from both constituent oxides. Furthermore, optical properties of thin films are investigated by performing UV–Vis spectrophotometer measurements. In the visible region, transmittance of all investigated thin films attains values as high as 85%. Moreover, refractive index of pure ZnO film was found to exhibit values ranging between 1.57 and 1.85 while for CeO2 thin film, it exhibits values ranging between 1.73 and 2.25 as the wavelength of incident light decreases from 700 nm to 400 nm. Remarkably, refractive index of ZnO:CeO2 mixed oxide-thin films are tuned by controlling the concentration of CeO2 properly. Mixed oxide-thin films of controllable refractive indices constitute an important class of smart functional materials. We have also investigated the optoelectronic and dispersion properties of ZnO:CeO2 mixed oxide-thin films by employing well-established classical models. The melodramatic boost of optical and optoelectronic properties of ZnO:CeO2 mixed oxide thin films establish a strong ground to modify these properties in a skillful manner enabling their use as key potential candidates for the fabrication of scaled optoelectronic devices and thin film transistors.

Photocatalytic Degradation of Methylene Blue by NiO Thin Films under Solar Light Irradiation

2019 ◽  
Vol 56 ◽  
pp. 152-157 ◽  
Author(s):  
Abdelouahab Noua ◽  
Hichem Farh ◽  
Rebai Guemini ◽  
Oussama Zaoui ◽  
Tarek Diab Ounis ◽  
...  
Keyword(s):  
Thin Films ◽  
Methylene Blue ◽  
Photocatalytic Activity ◽  
Sol Gel ◽  
Visible Region ◽  
Optical Transmittance ◽  
Dip Coating ◽  
Light Irradiation ◽  
Solar Light ◽  
Solar Light Irradiation

Nickel oxide (NiO) thin films were successfully deposited by sol-gel dip-coating method on glass substrates. The structural, morphological and optical properties in addition to the photocatalytic activity of the prepared films were investigated. The results show that the films have a polycrystalline NiO cubic structure with dense NiO grains and average optical transmittance in the visible region. The photocatalytic properties of the films were studied through the degradation of methylene blue and 89% of degradation was achieved for 4.5h of solar light irradiation exposure which indicates the capability of NiO photocatalytic activity.

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