Quantifying the Overall Efficiency of Circularly Polarized Emitters

Abstract

An increasing number of circularly polarized luminescence (CPL) molecular emitters has been developed in recent years and many of them are intended for applications in which high overall CPL efficiencies are required. In order to have a complete picture of the efficiency of a CPL emitter, dissymmetry factor (glum) is not enough. In the following we propose a new quantity, named CPL brightness (BCPL), which takes into account absorption extinction coefficient and quantum yield along with the glum factor. We calculated BCPL value for more than 180 compounds reported in the literature and we analyse data distribution for the main classes of CPL molecular emitters. This tool can be employed to put into context new CPL active compounds and to direct the choice of molecular systems for specific CPL applications.

Influence of Positional Isomerism on the Chiroptical Properties of Functional Aromatic Oligoamide Foldamers

“…[c] CPL brightness. [28] ogy with previous reports, the enantiomer bearing the (1S)-(À )camphanyl chiral inducer adopts a P helicity, leading to a positive Cotton effect at~400 nm. Conversely, the enantiomer bearing the (1R)-(+)-camphanyl chiral inducer adopts M helicity, thus showing a negative Cotton effect for low energy transitions.…”

“…The B CPL values obtained for the quinoline hexamer series are perfectly in the range of other types of organic CPL emitters. [28] Moreover the CPL brightness parameter better highlights the beneficial effect of the push-pull structure since Q 6 DFA (2) CF 3 (6) shows a CPL brightness (B CPL = 4.6) more than twice that of Q 6 DFA (2) (B CPL = 2.1).…”

Octagon‐Embedded Carbohelicene as a Chiral Motif for Circularly Polarized Luminescence Emission of Saddle‐Helix Nanographenes

“…Recently,t he efficiency of the CPL response is considered to be better quantified by the CPL brightness (B CPL )o rthe circularly polarization luminosity (L CPL )t aking also into account the absorption and the luminescence quantum yield. [40] In that case, B CPL for 2 (e F g lum /2) results in 1.30 M À1 cm À1 ,h igher than that of HBT (0.702 M À1 cm À1 ).…”

Time‐resolved circularly polarized luminescence of Eu3+‐based systems

“…ECID is related to the luminescence dissymmetry factor, g lum = 2( I L − I R )/( I L + I R ) , which is on the order of 10 −3 or less for most (luminescent) organic chiral molecules and significantly higher for some emission lines of chiral lanthanide complexes and supramolecular assemblies 2 . Although there are some chiral organic architectures with higher g lum , they are rare and still fall short of chiral lanthanide complexes 3,4 …”

“…2 Although there are some chiral organic architectures with higher g lum , they are rare and still fall short of chiral lanthanide complexes. 3,4 Chiral europium(III) complexes are well known for their emission lines with strong g lum . Their photophysical properties are relatively simple compared with other lanthanides, as the emitting level, labeled 5 D 0 , is nondegenerate, and a set of transitions from this level to the manifold of the 7 F J (J = 0-6) states can be typically observed.…”