Due to the characteristics of optical rotation, selective emission of polarized light, and circular dichroism, circularly polarized luminescent materials have aroused extensive attentions, and they have exhibited wide optoelectronic applications, such as optical data storage, liquid crystal display, and backlights in 3D displays. Here, the research progress of circularly polarized luminescent materials for organic optoelectronic devices is summarized. First, the definition and measurement of the circularly polarized light, such as optical rotatory dispersion, circular dichroism, and circularly polarized luminescence, are systematically introduced. Subsequently, the design strategies for various kinds of circularly polarized luminescent materials, including luminescent lanthanide and transition‐metal complexes, small organic luminophores, conjugated polymers, supramolecules, and liquid crystals are summarized. These materials exhibit circularly polarized luminescence with different magnitudes of luminescence dissymmetry values (glum). They are further applied in optoelectronic devices with excellent performance, and the influence factors on the glum values of these materials are presented in detail. Finally, the current opportunities and challenges in this rapidly growing research field are discussed systematically. The circularly polarized luminescent materials with large glum and high luminescence efficiency are very promising for applications in organic optoelectronic fields.

To lower deposition temperature and reduce thermal mismatch induced stress, heteroepitaxial growth of single-crystalline 3C-SiC on 150 mm Si wafers was investigated at 1000 o C using alternating supply epitaxy. The growth was performed in a hot-wall low-pressure chemical vapour deposition reactor, with silane and acetylene being employed as precursors. To avoid contamination of Si substrate, the reactor was filled in with oxygen to grow silicon dioxide, and then this thin oxide layer was etched away by silane, followed by a carbonization step performed at 750 o C before the temperature was ramped up to 1000 o C to start the growth of SiC. Microstructure analyses demonstrated that single-crystalline 3C-SiC is epitaxially grown on Si substrate and the film quality is improved as thickness increases. The growth rate varied from 0.44 to 0.76 ± 0.02 nm/cycle by adjusting the supply volume of SiH 4 and C 2 H 2. The thickness nonuniformity across wafer was controlled with ± 1 %. For a prime

applications in optical data storage, backlights in 3D displays and liquidcrystal display, spin sources in optical spintronics, and information carriers in quantum computation. [1][2][3][4][5][6][7][8][9][10] For CPL, the luminescence dissymmetry factor (g factor) is an important parameter to evaluate the degree of polarization, which is defined as g = ΔI/I = 2(I L − I R )/(I L + I R ), where I L and I R represent the left and right-handed luminescence polarized intensity values, respectively. [11,12] Currently, CP light is often obtained from nonpolarized light through the filters, which however results in low efficiency and high cost. So it is necessary to develop a new generation of device that can directly emit CP light. [13] Circularly polarized phosphorescent organic light-emitting diodes (CP-PhOLEDs) based on transition metal complexes, such as those of Ir(III) and Pt(II), are able to achieve theoretically 100% internal quantum efficiency through harvesting triplet excitons because singlet and triplet excitons can be synchronously utilized by spin-orbit coupling interactions induced by heavy metal atoms. [14][15][16][17][18] To the best of our knowledge, there are few reports about the utilization of chiral phosphorescent Pt(II) or Ir(III) complexes in CP-PhOLEDs. For example, Shen et al. designed a series of Pt(II) complexes (see A1 in Figure 1 and Table S1, Supporting Information) bonding a chiral sulfoxide ligand, which showed red emission and possessed a relatively high g value of the order of 10 −3 but without further capitalizing on the devices. [19] More recently, Brandt et al. synthesized a phosphorescent Pt(II) complex (see A2 in Figure 1 and Table S1, Supporting Information) with helical chirality achieving efficient red phosphorescence emission of devices but with inferior device performance, and its highest |g EL | value was up to 0.38. [20] However, it is difficult to tune the emission color of these Pt(II) complexes to the shorter wavelength. Owing to the advantageous photophysical properties of phosphorescent Ir(III) complexes, such as high luminescence quantum yields and tunable emission colors, they are the most excellent candidate for CP-PhOLEDs. [21][22][23][24] However, there are very few reports about the use of phosphorescent Ir(III) complexes as chiral emissive dopants in CP-PhOLEDs. For example, Li et al. reported a series of iridium phosphor isomers by introducing a chiral carbon center (R/S-edp, (R)/(S)-2-(4-ethyl-4,5-dihydrooxazol-2-yl) phenol) as ancillary ligands to obtain enantiomeric Ir(III) complexes (see B1 and B2 in Figure 1 and Table S1, Circularly polarized organic light-emitting diodes (CP-OLEDs), which directly emit CP light from organic light-emitting diodes, have attracted considerable attention because of their wide applications in various photonic devices. In this work, a pair of chiral bis-cyclometalated phosphorescent iridium(III) isocyanide complexes is designed and synthesized, which exhibits almost the same photophysical properties and obvious mirror image in ...

The influence of crystal defects on the gauge factor of p-type single crystalline 3C-SiC thin films is reported.

During the last few years, organoboron‐based thermally activated delayed fluorescence (TADF) materials have received extensive attention in optoelectronic area, owing to the unique electronegativity of boron atom. Herein, many research progress of organoboron‐based TADF materials for organic optoelectronic devices is summarized. This review comprehensively documents the organoboron‐based TADF materials according to the emission colors from blue to red‐near‐infrared (red‐NIR), covering the molecular design strategies, photophysical properties, and optoelectronic performance in organic light‐emitting diodes (OLEDs). The current progress and future challenges in this fast‐growing fields are reviewed systematically, providing instructive guidance for the future research on high‐performance TADF‐OLEDs.

Thermally activated delayed fluorescence (TADF) materials based on multiple resonance (MR) effect exhibit enormous potentials in organic light‐emitting diodes (OLEDs) with high color purity due to their intrinsically narrow emission. However, most of MR‐TADF emitters are limited to the boron‐nitrogen‐based rigid skeleton. In this work, three novel MR‐TADF emitters, namely CzBNO, DMAcBNO and DPAcBNO, are elaborately constructed, the TADF properties of which are realized by virtue of opposite MR effect of boron and nitrogen/oxygen atom. CzBNO‐based deep blue‐emitting OLEDs achieve a maximum external quantum efficiency (EQE) of 13.6% with a small FWHM of 36 nm, as well as a Commission Internationale de l'Eclairage (CIE) coordinate of (0.14,0.08). While the other two emitter‐based devices exhibit blue emission with a maximum EQE of up to 23.0%. To further improve the OLEDs performances, DMAcBNO and DPAcBNO‐based devices assisted by a sensitizer exhibit an excellent EQE of up to 29.6% with a relatively small efficiency roll‐off.

a b s t r a c tThe potential for enhancement of Si-based devices by growth of SiC films on large-diameter Si wafers is hampered by the very high temperatures (close to the Si melting temperature) that are needed for growth and doping by the existing techniques. Here, we present a unique doping method for growth of Al-doped single-crystalline 3C-SiC epilayers on 150 mm Si(1 0 0) substrates by atomic-layer epitaxy at 1000 1C using a conventional low-pressure chemical vapor deposition reactor. Al atomic concentration in the range of 2.8 Â 10 19 to 2.1 Â 10 20 cm À 3 , proportional to the supply volume of trimethylaluminium, is experimentally demonstrated. A doping mechanism, based on the supply sequence of precursors and reactor pressure, is proposed.

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