Circularly polarized light exhibits promising applications in future displays and photonic technologies. Circularly polarized luminescence (CPL) from chiral luminophores is an ideal approach to directly generating circularly polarized light, in which the energy loss induced by the circularly polarized filters can be reduced. Among various chiral luminophores, organic micro-/nano-structures have attracted increasing attention owing to the high quantum efficiency and luminescence dissymmetry factor. Herein, the recent progress of CPL from organic micro-/nano-structures is summarized. Firstly, the design principles of CPL-active organic micro-/nano-structures are expounded from the construction of micro-/nano-structure and the introduction of chirality. Based on these design principles, several typical organic micro-/nano-structures with CPL activity are introduced in detail, including self-assembly of small molecules, self-assembly of π-conjugated polymers, and self-assembly on micro-/nanoscale architectures. Subsequently, we discuss the external stimuli that can regulate CPL performance, including solvents, pH value, metal ions, mechanical force, and temperature. We also summarize the applications of CPL-active materials in organic light-emitting diodes, optical information processing, and chemical and biological sensing. Finally, the current challenges and prospects in this emerging field are presented. It is expected that this review will provide a guide for the design of excellent CPL-active materials.

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 ...

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