Control of Circularly Polarized Electroluminescence in Induced Twist Structure of Conjugate Polymer

Abstract

An extremely high degree of circularly polarized photoluminescence (CPPL) and electroluminescence (CPEL) (dissymmetry factor values: |g | = 0.72 and |g | = 1.13) are generated from twisted stacking of achiral conjugated polymer induced by nonemitting chiral dopant of high helical twisting power for the first time. Using a theoretical analysis incorporating the Stokes parameter, the twisting angle and birefringence of the aligned conjugated polymer, and the degree of linear polarization in the emitted light are found to make a roughly equal contribution to the degree of CPEL as to the degree of CPPL. Moreover, it is also found that the location of the recombination zone within the emitting layer is a crucial parameter for determining the difference in the dissymmetry factor between CPEL and CPPL. This result is applied to an organic light-emitting display to improve the luminous efficiency by 60%.

P‐170: Circularly Polarized Electroluminescence in a Low Molecular Weight Mesogenic Compound

“…We obtained HTP = 134.4 µm -1 by fitting the data to p ~ 1 / (HTP × c) where p and c are the pitch of the twisted stacking and concentration of the dopant, respectively. This value is very large compared to the HTP of the chiral dopant for the polymer as shown in the previous study and is reasonable results because it has a very small molecular weight as compared with the polymer [13].…”

“…We evaluated the CP property of the twist structure by the Müller matrix calculation using the parameters of the device such as degree of linear polarization, thickness, wavelength of emission, birefringence, twist angle of EML [13]. The degree of linear polarization of the PL was measured in the uniaxially aligned linearly polarized OLED without chiral dopant were 0.85.…”

“…In this case, linearly polarized light emitted from anisotropic molecules change to CP light by passing through twist stacking of birefringent materials. Also, it has a high circular polarization characteristic and the polarization state can be manipulated by controlling various parameters such as refractive index, wavelength, thickness, and twist angle of the EML [13]. The emitted CP light is defined as g-factor and expressed as 2 (IL-IR) / (IL+IR).…”

Outstanding Chiroptical Features of Thin Films of Chiral Oligothiophenes

“…The crude product was purified through column chromatography (SiO 2 , n-hexane/CH 2 Cl 2 90 : 10) to give 8 (1.17 g, yield 82%) as orange oil. 1 (7). Benzo[1, 2-b:4,5-b']dithiophene-4,8-diol (5) (1.03 g, 4.63 mmol), (S)-1-bromo-3,7-dimethyloctane (2.56 g, 11.6 mmol), K 2 CO 3 (6.40 g, 46.3 mmol), 18-crown-6 (12 mg, 0.045 mmol) and CH 3 CN (100 mL) were mixed together.…”

“…Chirality in organic optoelectronic devices is a topic that is rapidly gaining interest . There is at least a two‐fold interest: in the first place it can constitute a means to drive and control the supramolecular order of π‐conjugated molecules constituting the active layers of the devices, and secondly it opens the way to highly specialized applications, such as producing (CP‐OLED), or detecting (CP‐OFET) circularly polarized (CP) light or specifically responding to analyte enantiomers in analytical sensors . Moreover, molecular chirality is a unique way to manipulate electron spins and to construct spin filters .…”