Showing papers by "Tao Tao published in 2019"
TL;DR: Two very long bis(anthraoxa)quinodimethanes with nine (ABA) and ten (ANA) consecutively fused six-membered rings with a planar backbone with a typical quinoidal character are synthesised.
Abstract: We report the challenging synthesis of two very long bis(anthraoxa)quinodimethanes with nine (ABA) and ten (ANA) consecutively fused six-membered rings. The former is stable with negligible diradical character, while the latter with a moderate diradical character (y0 = 25.0%) is reactive and an unexpected trifluoroacetic substituted product (ANA-TFA) was isolated. X-ray crystallographic analysis revealed a planar backbone with a typical quinoidal character for both. Their dications can be regarded as the isoelectronic structures of the respective nonacene and decacene. The dication ABA2+ and dianion ABA2– are open-shell singlet diradicaloids, while the longer dication ANA-TFA2+ and dianion ANA2– have closed-shell ground state, which can be explained by the different intramolecular Coulomb interactions. Both dianions have a bent backbone and can be considered as an isoelectronic structure of the tetraanion of nonacene and decacene, respectively.
51 citations
TL;DR: In this article, the diketopyrrolopyrrole boronate ester was used as a potential chemosensor for fluorescent analysis and selective detection of fluoride ion.
22 citations
TL;DR: In this paper, a new kind of perovskite, (FAI)0.14, was proposed for VASP under relative humidity (RH) higher than 50% in ambient air.
Abstract: In this work, we present a new kind of perovskite, (FAI)0.46(MAI)0.40(MABr)0.14(PbI2)0.86(PbBr2)0.14, the vacuum flash-assisted solution processing (VASP) of which can be carried out under relative humidity (RH) higher than 50% in ambient air. The smooth and highly crystalline perovskite showed a maximum PCE of 18.8% in perovskite solar cells. This kind of perovskite was demonstrated to be of good stability in ambient air. Holes and electrons have larger and more balanced diffusion lengths (643.7/621.9 nm) than those in the MAPbI3 perovskite (105.0/129.0 nm) according to the PL quenching experiment. The role of incorporating a large amount of MA+ cations to stabilize the intermediate phase via VASP under high RH is attributed to their better ability to intercalate into the sharing face of the one-dimensional face-sharing [PbI6] octahedra, forming the three-dimensional corner-sharing form. Moreover, hole/electron transfer times at the perovskite/Spiro-OMeTAD (PCBM) interfaces (8.90/9.20 ns) were found to be much larger than those in the MAPbI3 perovskite (0.75/0.40 ns), indicating that there still is enormous potential in further improving the performance of this kind of perovskite solar cell by interfacial engineering.
13 citations
TL;DR: The results reveal that the morphology could be controlled by using different types of alcohols, especially mixed alcohols and played a key role in determining the photodegradation efficiency of formaldehyde.
Abstract: Bi2O3/TiO2 photocatalysts were prepared by a hydrothermal method. The photocatalysts were applied to the catalytic oxidation of indoor formaldehyde vapors under irradiation by an light-emitting dio...
13 citations
TL;DR: For the first time rhenium-containing biimidazoles have been structurally reported with two triphenylethylene units following chiral and cis-trans transformations simultaneously as discussed by the authors.
Abstract: For the first time rhenium-containing biimidazoles have been structurally reported with two triphenylethylene units following chiral and cis–trans transformations simultaneously. Crystal structures show that the biimidazole ligand exhibits an (M)-trans-(P) configuration, whereas the (M)-cis-(M) mode was observed in the rhenium complex, showing cis–trans configurations between biimidazoles and the relative chiral isomers among adjacent triphenylvinylimidazole units. Furthermore, aiming to verify the association rule between spectral behaviours and orientational changes, fluorescence titration experiments were performed for full comparison where the detection performance for explosives in an aqueous phase depends on the alternation of the molecular structure, including the introduction of two alkyl chains and fac-[Re(CO)3Cl]. In addition, computational studies on molecular conformations with different torsion angles for related compounds were carried out.
12 citations
TL;DR: In this paper, a hexagonal single crystal GaN layer with (002) orientation was successfully obtained by nitridating β-Ga2O3 film under NH3 flow despite structural mismatch between β-GO3 and hexagonal GaN, which shows a network structure without significant stress, which makes it very suitable to be used as a template for the epitaxial growth of high quality GaN films.
Abstract: We have successfully obtained a hexagonal single crystal GaN layer with (002) orientation by nitridating β-Ga2O3 film under NH3 flow despite structural mismatch between β-Ga2O3 and hexagonal GaN. The conversion process of β-Ga2O3 to GaN has also been systematically investigated. The nitridated GaN layer shows a network structure without significant stress, which makes it very suitable to be used as a template for the epitaxial growth of high-quality GaN films. The GaN/Ga2O3 heterostructure can also be used to obtain free-standing GaN (FS-GaN) films by self-separation or chemical lift-off (CLO) process due to the selective etching of β-Ga2O3. Further investigation demonstrates the feasibility of the in situ growth of low-stress FS-GaN substrates by halide vapor phase epitaxy (HVPE).
10 citations
TL;DR: In this article, the photocatalytic reduction of CO2 to form methyl formate (MF) in methanol was evaluated, and the results indicated that the CuOdecorated dual-phase TiO2 microspheres displayed MF yield of 1800μmol·g−1 under 4h illumination, higher than other reference photocatalyststs, due to its mixed-phase heterojunction structure and larger surface area, thus leading to an enhanced UV-light response, effective separation and low recombination rate of the photoinduced charge carriers.
10 citations
TL;DR: In this paper, a GaN template converted from β-Ga2O3 film contains many voids and exhibits good-crystallinity with (0'0'2' orientation.
5 citations
TL;DR: In this paper, the authors synthesize potential probes by simple synthesis to detect uniform weak acids and bases at a low cost with the naked eye, and demonstrate that the combination of azulene spacers and AIE chromophores enable the reversible responsiveness with redox and acid base processes.
5 citations
TL;DR: In this paper, a hybrid organic/inorganic III-nitride WLED was designed and fabricated based on Rubrene/(InGaN/GaN) MQWs p-n junction.
Abstract: It is known that the commercialized white light-emitting diodes (WLEDs) depend on phosphor conversion, which is limited by the unbalanced carrier injection in multiple quantum wells (MQWs) and low down-conversion efficiency. To solve these problems, hybrid organic/inorganic III-nitride WLEDs were designed and fabricated based on Rubrene/(InGaN/GaN) MQWs p-n junction. In such new structure, Rubrene can act as yellow–red emitter and play an important role in hole transport layer owing to its high carrier mobility. By optimizing the hybrid LED structure, the charge balance and recombination zone in radiative region were significantly improved. In this work, the optimal hybrid WLED with color coordinates of (0.31, 0.33) shows a maximum current efficiency of 15.22 cd/A with excellent long lifetime stability. The hybrid WLEDs based on organic/inorganic p-n junction were demonstrated with a good performance, which provides an attractive route to achieve high performance phosphor-free WLED sources for microdisplay or large-area WLED applications.
5 citations
TL;DR: In this paper, the preparation of porous single-crystal GaN films by direct top-down high temperature nitridation of β-Ga2O3 was reported, and the self-separation between the porous GaN film and sapphire was demonstrated.
TL;DR: The catalysts with Na2SO4 loading provided more surface-adsorbed oxygen that facilitated the desorption of CO2 and markedly increased the photocatalytic oxidation of HCHO, indicating that the solution mixing method was more favorable to increase the HCHO conversion due to decrease the size of Bi0.15Ti0.85O2 particles.
Abstract: Photocatalytic oxidation of formaldehyde (HCHO) is considered as one of the promising ways to resolve indoor air HCHO pollution. TiO2 has been well known as the most extended application in photocatalysis due to its strong oxidizing ability and stability. Owing to high activity under visible light irradiation, TiO2 and Bi2O3 doping mixed with Bi2WO6 was analyzed in this study. The formation of two kinds of heterojunction caused efficient charge separation, leading to the effective reduction in the recombination of photo-generated electron and hole. The special structure and enhanced performance of these catalysts were analyzed. For the first time, the loading of alkali salts was researched for photocatalytic oxidation. In order to understand the reaction mechanism of alkali salts enhanced effects, the catalysts were investigated by using BET, XRD, UV–Vis, FT-IR, SEM, and XPS. The results found more than 2 wt% of Na2SO4 loading and the mixed methods with different solutions were key factors affecting the performance of catalysts. Nearly 92% HCHO conversion could be completed over Bi2WO6/Bi0.15Ti0.85O2 (Na2SO4), and the concentration of HCHO was only 0.07 mg/m3 for 24 h, which was below the limit of specification in China. The results also indicated that the solution mixing method was more favorable to increase the HCHO conversion due to decrease the size of Bi0.15Ti0.85O2 particles. The catalysts with Na2SO4 loading provided more surface-adsorbed oxygen that facilitated the desorption of CO2 and markedly increased the photocatalytic oxidation of HCHO.
TL;DR: In this article, the currentvoltage characteristics of AlGaN ultraviolet light-emitting diodes (UV-LEDs) under the temperatures ranging from 50 K to 300 K were analyzed.
Abstract: Current-voltage ( I-V ) characteristics of AlGaN ultraviolet light-emitting diodes (UV-LEDs) under the temperatures ranging from 50 K to 300 K are analyzed. The abnormal diode characteristics of UV-LEDs below the turn-on voltage indicate the existence of space-charge-limited (SCL) current transport in the presence of deep trap states, which induce a non-linear current leakage effect. The SCL current is gradually overwhelmed by Ohmic leakage as the temperature increases, which is mainly due to the thermally generated carrier concentration and traps deactivation. A modified three-diode circuit model is suggested with an additional series resistor and diode to emulate the forward-bias I-V characteristics of UV-LEDs. An excellent fit to the I-V curves of UV-LEDs is achieved, which illustrates the impact of deep trap states on the electrical characteristics of UV-LEDs.
TL;DR: In this article, the authors have simulated the charge generation, transport and recombination in perovskite solar cells under standard AM 1.5G sunlight on the basis of solving hierarchical equations of motion with model Hamiltonian.
Abstract: Understanding the mechanism of photovoltaic conversion in perovskite solar cells (PSCs) remains a great challenge. In this work, we have simulated the charge generation, transport and recombination in PSCs under standard AM 1.5G sunlight on the basis of solving hierarchical equations of motion with model Hamiltonian. Reasonable current/voltage characteristics, power conversion efficiency (PCE), and incident photon to current conversion efficiency (IPCE) can be obtained by investigating different interaction with respect to the interfacial recombination. Moreover, it is found that the interfacial charge transfer (CT) states can greatly affect the current/voltage characteristics, which is elucidated by analyzing the density of states. Dynamics response of current to sunlight or bias is demonstrated and the intrinsic temperature effect on PCE is also discussed.
04 Oct 2019