Executive Summary : | Circularly polarized light (CPL) refers to the light in which the electric vector of propagating light remains perpendicular to the direction of propagation along with its magnitude. CPL can be obtained from the non-polarized light by using a linear polarizer and quarter-wave plate continuously. However, this leads to the loss in the brightness and complex designs of the systems. Therefore, chiral optical materials are used to harness CPL. The CPL materials find huge applications in 3D displays, information storage and processing, biological probes and spintronic-based devices. In this proposal, we plan to focus on harnessing the CPL-based thermally activated delayed fluorescence (TADF) materials for the application in organic light emitting diodes (OLEDs). Generally, the chiral conjugated polymers and chiral metal complexes are considered for the display devices. But due to the instability of such polymers and high-cost metal complexes (Eu, Ir, and Pt), small organic molecules are considered for practical applications. The efficiency of a normal luminescent molecule is determined by the photoluminescence quantum yield (PLQY), while the efficiency of the polarized systems is determined by the high luminescence dissymmetry factor (glum) along with the PLQY. The glum factor quantifies the CPL efficiency between the -2 and +2, while the zero value indicates that emitting light has no circular polarization. The value of -2 and +2 suggests the highest value of left or right polarized light, respectively.
The various methods have been utilized in order to incorporate the chirality in organic molecular systems like (i) point chirality, (ii) helical chirality, (iii) axial chirality, (iv) propeller chirality, and (v) planar chirality. However, none of these methods individually lead to the higher value of glum, hence restricting these materials' practical applications. Therefore, we propose a new strategy to harness the CPL-based luminescent molecules to overcome the problems associated with these methods, i.e . introducing the two different kinds of chirality (chiral center-axial and helical-axial) in the same molecular system, it will amplify the glum factor. |