TY  - JOUR
A1  - Chen, Xing
A1  - Meng, Guoyun
A1  - Liao, Guanming
A1  - Rauch, Florian
A1  - He, Jiang
A1  - Friedrich, Alexandra
A1  - Marder, Todd B.
A1  - Wang, Nan
A1  - Chen, Pangkuan
A1  - Wang, Suning
A1  - Yin, Xiaodong
T1  - Highly Emissive 9-Borafluorene Derivatives: Synthesis, Photophysical Properties and Device Fabrication
JF  - Chemistry—A European Journal
N2  - A series of 9-borafluorene derivatives, functionalised with electron-donating groups, have been prepared. Some of these 9-borafluorene compounds exhibit strong yellowish emission in solution and in the solid state with relatively high quantum yields (up to 73.6 % for FMesB-Cz as a neat film). The results suggest that the highly twisted donor groups suppress charge transfer, but the intrinsic photophysical properties of the 9-borafluorene systems remain. The new compounds showed enhanced stability towards the atmosphere, and exhibited excellent thermal stability, revealing their potential for application in materials science. Organic light-emitting diode (OLED) devices were fabricated with two of the highly emissive compounds, and they exhibited strong yellow-greenish electroluminescence, with a maximum luminance intensity of >22 000 cd m\(^{-2}\). These are the first two examples of 9-borafluorene derivatives being used as light-emitting materials in OLED devices, and they have enabled us to achieve a balance between maintaining their intrinsic properties while improving their stability.
KW  - boron heterocycles
KW  - photophysics
KW  - organic light-emitting diodes
KW  - luminescence
KW  - density functional calculations
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-256738
VL  - 27
IS  - 20
ER  - 
TY  - JOUR
A1  - He, Jiangang
A1  - Di Sante, Domenico
A1  - Li, Ronghan
A1  - Chen, Xing-Qiu
A1  - Rondinelli, James M.
A1  - Franchini, Cesare
T1  - Tunable metal-insulator transition, Rashba effect and Weyl Fermions in a relativistic charge-ordered ferroelectric oxide
JF  - Nature Communications
N2  - Controllable metal–insulator transitions (MIT), Rashba–Dresselhaus (RD) spin splitting, and Weyl semimetals are promising schemes for realizing processing devices. Complex oxides are a desirable materials platform for such devices, as they host delicate and tunable charge, spin, orbital, and lattice degrees of freedoms. Here, using first-principles calculations and symmetry analysis, we identify an electric-field tunable MIT, RD effect, and Weyl semimetal in a known, charge-ordered, and polar relativistic oxide Ag2BiO3 at room temperature. Remarkably, a centrosymmetric BiO6 octahedral-breathing distortion induces a sizable spontaneous ferroelectric polarization through Bi3+/Bi5+ charge disproportionation, which stabilizes simultaneously the insulating phase. The continuous attenuation of the Bi3+/Bi5+ disproportionation obtained by applying an external electric field reduces the band gap and RD spin splitting and drives the phase transition from a ferroelectric RD insulator to a paraelectric Dirac semimetal, through a topological Weyl semimetal intermediate state. These findings suggest that Ag2BiO3 is a promising material for spin-orbitonic applications.
KW  - electronic properties and materials
KW  - ferroelectrics and multiferroics
KW  - topological matter
Y1  - 2018
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-227946
VL  - 9
ER  -