scholarly journals TADF/RTP OLED organic emitters based on concaved N-PAHs with tunable intrinsic D-A electronic structure

2021 ◽  
Author(s):  
Jakub Wagner ◽  
Paola Zimmermann Crocomo ◽  
Michał Kochman ◽  
Adam Kubas ◽  
Przemysław Data ◽  
...  
Keyword(s):  
Aromatic Hydrocarbons ◽  
Electronic Structures ◽  
Quantum Yields ◽  
Proof Of Concept ◽  
Bandgap Engineering ◽  
Strong Electron ◽  
Effi Ciency ◽  
Polycyclic Aromatic ◽  
First Time ◽  
Homo Lumo

Polycyclic aromatic hydrocarbons (PAHs) with centrally positioned nitrogen dopants possess a unique curved structure and strong electron-donating features. However, the lack of tools to synthetically affect their bandgap engineering and charge-transfer (CT) characteristic is detrimental to their future optoelectronics use because of usually low PLQY effi-ciency. Facing this challenge, we report on developing the first fully conjugated, curved N-PAHs containing phenazine terminus with the D-A electronic structures, which are herein studied as functional optoelectronic material. We evidence the influence of curvature on minimizing HOMO-LUMO overlap, which was severely reflected in small ΔEST values, in-dispensable to enhance the RISC rate constant. Within this approach, we evaluate the utility of the concaved system as TADF/RTP emitters which has not been explored so far in the context of non-planar N-PAHs. By variable accepting strength of phenazines employed, the photoluminescence quantum yields (ΦPL) were tuned, ranging from the lowest 9% up to the highest 86% with dinitrile terminus. As a proof of concept, solid-state OLED devices were constructed, exhibit-ing yellow to orange emission with the best maximum external EL quantum efficiency (EQE) of 12% for acceptor built up on 3-(trifluoromethyl)phenyl decorated phenazine that is demonstrated for the first time for curved D-A embedded N-PAHs.

Carbonization in Titan Tholins: implication for low albedo on surfaces of Centaurs and trans-Neptunian objects

2015 ◽  
Vol 15 (3) ◽  
pp. 231-238 ◽  
Author(s):  
Chaitanya Giri ◽  
Christopher P. McKay ◽  
Fred Goesmann ◽  
Nadine Schäfer ◽  
Xiang Li ◽  
...  
Keyword(s):  
Aromatic Hydrocarbons ◽  
Organic Material ◽  
Near Infrared ◽  
Proof Of Concept ◽  
Astronomical Observations ◽  
Polycyclic Aromatic ◽  
Large Polycyclic Aromatic Hydrocarbons ◽  
Characteristic Features ◽  
Complex Organic ◽  
Geometric Albedo

AbstractAstronomical observations of Centaurs and trans-Neptunian objects (TNOs) yield two characteristic features – near-infrared (NIR) reflectance and low geometric albedo. The first feature apparently originates due to complex organic material on their surfaces, but the origin of the material contributing to low albedo is not well understood. Titan tholins synthesized to simulate aerosols in the atmosphere of Saturn's moon Titan have also been used for simulating the NIR reflectances of several Centaurs and TNOs. Here, we report novel detections of large polycyclic aromatic hydrocarbons, nanoscopic soot aggregates and cauliflower-like graphite within Titan tholins. We put forth a proof of concept stating the surfaces of Centaurs and TNOs may perhaps comprise of highly ‘carbonized’ complex organic material, analogous to the tholins we investigated. Such material would apparently be capable of contributing to the NIR reflectances and to the low geometric albedos simultaneously.

scholarly journals Sources and transformations of particle-bound polycyclic aromatic hydrocarbons in Mexico City

2005 ◽  
Vol 5 (6) ◽  
pp. 12741-12773 ◽  
Author(s):  
L. C. Marr ◽  
K. Dzepina ◽  
J. L. Jimenez ◽  
F. Reisen ◽  
H. L. Bethel ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Polycyclic Aromatic Hydrocarbons ◽  
Mexico City ◽  
Aromatic Hydrocarbons ◽  
Heterogeneous Reactions ◽  
Field Campaign ◽  
Aerosol Mass ◽  
Aerosol Mass Spectrometry ◽  
Polycyclic Aromatic ◽  
First Time

Abstract. Understanding sources, concentrations, and transformation of polycyclic aromatic hydrocarbons (PAHs) in the atmosphere is important because of their potent mutagenicity and carcinogenicity. The measurement of particle-bound PAHs by three different methods during the Mexico City Metropolitan Area field campaign in April 2003 presents a unique opportunity for characterization of these compounds and assessment of the methods. The three methods are (1) collection and analysis of bulk samples for time-integrated gas- and particle-phase speciation by gas chromatography/mass spectrometry; (2) aerosol photoionization for fast detection of PAHs on particles' surfaces; and (3) aerosol mass spectrometry for fast analysis of size and chemical composition. This research represents the first time aerosol mass spectrometry has been used to measure ambient PAH concentrations and the first time that fast, real-time methods have been used to quantify PAHs alongside traditional filter-based measurements in an extended field campaign. Speciated PAH measurements suggest that motor vehicles and garbage and wood burning are important sources in Mexico City. The diurnal concentration patterns captured by aerosol photoionization and aerosol mass spectrometry are generally consistent. Ambient concentrations typically peak at ~110 ng m−3 during the morning rush hour and rapidly decay due to changes in source activity patterns and dilution as the boundary layer rises, although surface-bound PAH concentrations decay faster. The more rapid decrease in surface versus bulk PAH concentrations during the late morning suggests that freshly emitted combustion-related particles are quickly coated by secondary aerosol material in Mexico City's atmosphere and may also be transformed by heterogeneous reactions.

scholarly journals Site-Selective [2+2+n] Cycloadditions for Rapid, Scalable Access to Alkynylated Polycyclic Aromatic Hydrocarbons

2019 ◽  
Author(s):  
Gavin R. Kiel ◽  
Harrison Bergman ◽  
T. Don Tilley
Keyword(s):  
Polycyclic Aromatic Hydrocarbons ◽  
Aromatic Hydrocarbons ◽  
Structural Complexity ◽  
Building Blocks ◽  
Synthetic Methods ◽  
Proof Of Concept ◽  
Site Selectivity ◽  
Polycyclic Aromatic ◽  
Site Selective ◽  
Nanometer Regime

Polycyclic aromatic hydrocarbons (PAHs) are attractive synthetic building blocks for more complex conjugated nanocarbons, but their use for this purpose requires appreciable quantities of a PAH with reactive functional groups. Despite tremendous recent advances, most synthetic methods cannot satisfy these demands. Here we present a general and scalable [2+2+n] (n = 1 or 2) cycloaddition strategy to access PAHs that are decorated with synthetically versatile alkynyl groups and its application to seven structurally diverse PAH ring systems (thirteen new alkynylated PAHs in total). The critical discovery is the site-selectivity of an Ir-catalyzed [2+2+2] cycloaddition, which preferentially cyclizes tethered diyne units with preservation of other (peripheral) alkynyl groups. The potential for generalization of the site-selectivity to other [2+2+n] reactions is demonstrated by identification of a Cp<sub>2</sub>Zr-mediated [2+2+1] / metallacycle transfer sequence for synthesis of an alkynylated, selenophene-annulated PAH. The new PAHs are excellent synthons for macrocyclic conjugated nanocarbons. As a proof of concept, four were subjected to Mo catalysis to afford large, PAH-containing arylene ethylene macrocycles, which possess a range of cavity sizes reaching well into the nanometer regime. More generally, this work is a demonstration of how site-selective reactions can be harnessed to rapidly build up structural complexity in a practical, scalable fashion.

scholarly journals The well correlated diffuse interstellar bands at λλ 6196, 6614 Å and their possible companions

2020 ◽  
Vol 496 (2) ◽  
pp. 2231-2240
Author(s):  
A Bondar
Keyword(s):  
Polycyclic Aromatic Hydrocarbons ◽  
High Resolution ◽  
Aromatic Hydrocarbons ◽  
Correlation Coefficients ◽  
High Signal ◽  
Signal To Noise ◽  
B Stars ◽  
Diffuse Interstellar Bands ◽  
Polycyclic Aromatic ◽  
First Time

ABSTRACT Considered here is the interrelation between five diffuse interstellar bands (DIBs), λλ 5545, 6113, 6196, 6445 and 6614 Å. Two DIBs (λλ 6196 and 6614 Å) are already known as being well correlated with each other; their relation with three other weaker bands is investigated for the first time. To accomplish this task, high-resolution spectra (λ/δλ ≈100 000) with high signal-to-noise ratios (S/N) of 54 hot O–B stars with reddening 0.12–1.45 mag were used. Analysis of measured equivalent widths has allowed us to establish linear dependences and evaluate linear correlation coefficients as high as 0.968–0.988 between the intensities of these five DIBs. Such a degree of correlation may indicate their common origin. Several spacings in wavenumbers found between these DIBs correspond to the energies of vibrational transitions in some polycyclic aromatic hydrocarbons resulting in IR emissions at λλ 16.4, 11.3, 7.7, 6.2 and 3.3 μm.

scholarly journals Subgap Two-Photon States in Polycyclic Aromatic Hydrocarbons: Evidence for Strong Electron Correlations

2014 ◽  
Vol 118 (6) ◽  
pp. 3331-3339 ◽  
Author(s):  
Karan Aryanpour ◽  
Adam Roberts ◽  
Arvinder Sandhu ◽  
Rajendra Rathore ◽  
Alok Shukla ◽  
...  
Keyword(s):  
Polycyclic Aromatic Hydrocarbons ◽  
Aromatic Hydrocarbons ◽  
Electron Correlations ◽  
Strong Electron ◽  
Strong Electron Correlations ◽  
Two Photon ◽  
Polycyclic Aromatic ◽  
Photon States

Determination of Polycyclic Aromatic Hydrocarbons in the Presence of Humic Acid in water

2016 ◽  
Vol 70 (9) ◽  
pp. 1520-1528 ◽  
Author(s):  
Ruifang Yang ◽  
Nanjing Zhao ◽  
Xue Xiao ◽  
Shaohui Yu ◽  
Jianguo Liu ◽  
...  
Keyword(s):  
Polycyclic Aromatic Hydrocarbons ◽  
Humic Acid ◽  
Aromatic Hydrocarbons ◽  
Fluorescence Quantum Yield ◽  
Quantum Yields ◽  
Fluorescence Quantum Yields ◽  
Polycyclic Aromatic ◽  
Pahs Concentration ◽  
Test Sets

The presence of humic acid (HA) makes it extremely difficult to determine and quantify accurately polycyclic aromatic hydrocarbons (PAHs) in aquatic environment because of their complex and strong interaction. To solve this problem, a new method was developed in this work through the combination of PARAFAC and fluorescence spectroscopy, which mainly includes: (1) the fluorescence quantum yield acquisition of PAHs with and without HA by PARAFAC; (2) the  concentration score correction of PAHs in validation and test sets using the fluorescence quantum yields; and (3) the prediction of PAHs concentration in the validation and test sets in the presence of HA by corrected concentration. Using this method, the PAHs concentration on the level of µg L−1 in the test samples with HA of 2.5 mg/L and 5.0 mg/L can be successfully predicted with the root mean square error below 0.15 µg L−1, relative error of prediction below 4% for validation samples, recoveries of each PAH between 82.5% and 102.6% for test samples.

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