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Dive into the research topics where Xiaohong Shang is active.

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Featured researches published by Xiaohong Shang.


New Journal of Chemistry | 2016

Theoretical investigation of photophysical properties for a series of iridium(III) complexes with different substituted 2,5-diphenyl-1,3,4-oxadiazole

Xiaohong Shang; Yanan Li; Qing Zhan; Gang Zhang

A quantum chemical investigation from structural and electronic properties and some charge-transport parameter viewpoints was performed on several homoleptic iridium complexes [(C∧N)2Ir(pic)] with the 2,5-diaryl-1,3,4-oxadia-zoles moiety in C∧N ligands, where pic represents the picolinate ancillary ligand. Complex 2 exhibits its blue phosphorescent emission with maxima at 485 nm. Furthermore, to obtain the mechanism of high phosphorescence yield in 2, we estimated the radiative rate constant kr, the contribution of 3MLCT in the T1 state, S1–T1 energy gap ΔES1–T1, and the transition dipole moment in the S0 → S1 transition μS1 for 2. Comparison of calculated results for the four complexes shows that the designed complex 2 may possess higher photoluminescent quantum efficiency than the others, making it a potential candidate as an efficient blue-emitting material.


RSC Advances | 2017

A theoretical study on the electronic and photophysical properties of two series of iridium( iii ) complexes with different substituted N^N ligand

Xiaohong Shang; Deming Han; Mei Liu; Gang Zhang

A density functional theory/time-depended density functional theory has been applied to explore the geometrical, electronic and photophysical properties of the recently reported pyrazolyl-pyridine- or triazolyl-pyridine-containing iridium(III) complexes 1 and 2. The calculated absorption and emission wavelengths are in agreement with experimental data. Based on complexes 1 and 2, two series of Ir(III) complexes 1a–1c and 2a–2c with different N^N ligand have been designed. It is found that the photophysical properties of these complexes are greatly affected by the properties of the adopted ligands. From 2 to 2c, the ancillary ligands based on a bis(triazolyl-pyridine) moiety with a m-phenylene spacer group render an increase of the HOMO–LUMO energy gap, but relatively weak absorption intensities. It is believed that the larger 3MC/d–d → 3MLCT/π–π* energy gap, higher μS1 and MLCT % values, as well as the smaller ΔES1–T1 for 2b and 2c, are good indications for the higher quantum efficiency compared with that of experimental structure 2. Therefore, the newly designed complexes 2b and 2c are expected to be highly efficient deep-blue emitters for OLEDs application.


New Journal of Chemistry | 2015

Theoretical investigation of the effects of N-substitution on the photophysical properties of two series of iridium(III) complexes

Xiaohong Shang; Deming Han; Qing Zhan; Defeng Zhou; Gang Zhang

Based on the complexes [Ir(dfb-pz)2(tfmtyp)] (1) and [Ir(tfmfb-pz)2(tfmtyp)] (2) [dfb-pz = 2,4-difluorobenzyl-N-pyrazole; tfmtyp = 2-(5-trifluoromethyl-[1,2,4]triazol-3-yl)-pyridine; tfmfb-pz = 2-tri-fluoromethyl-5-fluorobenzyl-N-pyrazole], two series of Ir(III) complexes have been designed by substituting “CH” groups with the N atom at -a, -b, -c, and -d positions on the pyridine moiety in N^N ligands. The electronic structure, absorption and emission spectra as well as phosphorescence efficiency of all these Ir(III) complexes were investigated by using density functional theory (DFT) and time-dependent DFT (TDDFT) methods. The calculated results show that the assumed complexes 1a and 2a may possess a higher photoluminescent quantum efficiency than other complexes and are potential candidates as efficient blue-emitting materials. This study shows that the N substitution can tune the emission color of 1 and 2 and enhance the photoluminescence quantum efficiency.


Journal of Applied Physics | 2010

Quenching mechanisms of the optical centers in Eu3+-doped nanophosphors under charge transfer excitation

Chunyu Shang; Xiaohong Shang; Yuqiu Qu; Meicheng Li

As the size of Eu3+-doped phosphors decreases in nanoscale, the top of the valance band is elevated and the zero-phonon charge transfer (CT) energy is decreased; the rigidity of the lattice environment is decreased and the CT state (CTS) coordinate offset is enlarged. The decrease in zero-phonon CT energy and the enlargement of CTS coordinate offset mean the displacement of CTS in the configurational coordinate diagram (CCD). The CTS displacement in CCD results in the decrease in CTS feeding to the emitting D5 states and the increase in transition probability from the CTS to the F7 states, the excitation of the optical centers tends to be relaxed by sending phonons to the host lattice. Based on the quenching mechanisms of the optical centers progressively clarified in this paper, a feasible coating method is proposed to improve the luminescence efficiency for Eu3+-doped nanophosphors under CT excitation.


New Journal of Chemistry | 2017

Shedding light on the photophysical properties of iridium(III) complexes with a dicyclometalated phosphate ligand via N-substitution from a theoretical viewpoint

Xiaohong Shang; Deming Han; Defeng Zhou; Gang Zhang

The geometrical structures and phosphorescence efficiency of two series of iridium(III) complexes with wide-range color tuning have been focused on in this work. A DFT/TDDFT (density functional theory/time-dependent density functional theory) investigation on the electronic structure in the ground and lowest triplet excited states, the frontier molecular orbitals, the absorption spectra, and phosphorescence properties of 1–1d and 2–2d has been performed to get a better understanding of the relationship between the structure and property. Importantly, the nature of the N-substituents can influence the electron density distributions of frontier molecular orbitals and their energies, resulting in a change in transition character and emission color, while the attached –CF3 or –C(CH3)3 group on the triazole moiety has an impact on the radiative decay constants of all the complexes. The higher quantum yields of 1a, 1c, 2a, and 2c compared to 1b, 1d, 2b, and 2d can be explained by their larger separation between 3MLCT/π → π* and 3MC d–d states, and the designed 1a and 2a with high quantum efficiency are considered to be potential candidates for deep blue and blue-emitting materials, respectively.


Molecular Physics | 2014

Theoretical study on the electronic structures and phosphorescent properties of a series of iridium(III) complexes with N^C^N-coordinating terdentate ligands

Deming Han; Xiaohong Shang; Lihui Zhao; Xiuping Sun; Gang Zhang; Wei Ji

The geometry structures, electronic structures, absorption, and phosphorescent properties of a series of iridium(III) complexes with the structure Ir(N^C^N)(N^C)Cl, (N^C^N represents a terdentate coordination with different substituent groups C2H5 (1), NH2 (2), CH3 (3), H (4), CN (5), NO2 (6), and CF3 (7), N^C is 2-phenylpyridine) have been investigated using the density functional theory and time-dependent density functional theory. Calculations of ionisation potential and electron affinity were used to evaluate the injection abilities of holes and electrons into these complexes. The lowest energy absorption wavelength calculated is in good agreement with the experimental value. The lowest energy emissions of complexes 1−7 are localised at 552, 559, 549, 517, 627, 788, and 574 nm, respectively, at CAM-B3LYP level. For complexes 1 and 3, the calculated results showed a lower and larger 3MLCT contributions and higher values, which could result in the larger kr value than those of other complexes. It is anticipated that the theoretical studies can provide useful information for designing and synthesising the candidated phosphorescent material for use in the organic light-emitting diodes.


Molecular Crystals and Liquid Crystals | 2014

Theoretical Studies on the Electronic Structures and Phosphorescence Properties of Three Heteroleptic Cyclometalated Iridium(III) Complexes

Deming Han; Xiaohong Shang; Gang Zhang; Tian Li; Hongguang Li; Hongxing Cai; Xihe Zhang; Lihui Zhao

The geometry structures, electronic structures, absorption, and phosphorescence properties of three heteroleptic cyclometalated iridium(III) complexes have been theoretically investigated by the density functional theory (DFT) method. The highest occupied molecular orbital (HOMO) of the three complexes has the similar distributions on two main ligands. However, the lowest unoccupied molecular orbital (LUMO) of the three complexes has different distributions on different ligand fragments. Especially for 3, the LUMO is mainly composed of the picolinate auxiliary ligand. The lowest lying absorptions were calculated to be at 409, 473, and 414 nm for 1–3, respectively. By changing the conjugation length of the main ligand from 1 to 2, one can tune the emission color from green to red. The addition of sterically bulky phenolic substituents in 3 also results in an obvious red shift of the emission wavelength. The calculated results show that the absorption and emission transition character can be changed by altering the main ligands. Calculations of ionization potential (IP) and electron affinity (EA) were used to evaluate the injection abilities of holes and electrons into these complexes. The theoretical work should provide a suitable guide to the future design and synthesis of novel phosphorescent materials for use in the organic light-emitting diodes (OLEDs).


Chemical Physics Letters | 2013

Theoretical study of injection, transport, absorption and phosphorescence properties of a series of heteroleptic iridium(III) complexes in OLEDs

Xiaohong Shang; Deming Han; Dongfeng Li; Zhijian Wu


Chemical Physics Letters | 2011

Investigation on the red shift of charge transfer excitation spectra for nano-sized Y2O3:Eu3+

Chunyu Shang; Xiaohong Shang; Yuqiu Qu; Meicheng Li


Journal of Physical Chemistry C | 2011

Investigation on the Luminescence Improvement of Nanosized La2O3/Eu3+ Phosphor under Charge-Transfer Excitation

Chunyu Shang; Hongbo Jiang; Xiaohong Shang; Meicheng Li; Liancheng Zhao

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Deming Han

Changchun University of Science and Technology

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Chunyu Shang

Heilongjiang University of Science and Technology

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Lihui Zhao

Changchun University of Science and Technology

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Meicheng Li

Harbin Institute of Technology

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Ning Wan

Changchun University

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Yanan Li

Chinese Academy of Sciences

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