Emergent Nonreciprocal Circularly Polarized Emission from an Organic Thin Film

Abstract

Controlling circularly polarized (CP) emission is key for both fundamental understanding and applications in the field of chiral photonics and electronics. Here, a completely new way to achieve this goal is presented. A luminescent thin film, made from a chiral conjugated phenylene bis‐thiophenylpropynone able to self‐assemble into ordered structures, emits highly circularly polarized light with opposite handedness from its two opposite faces. Such emergent nonreciprocal behavior in CP emission, so far unprecedented, represents a fundamental advance, opening new opportunities in design, preparation, and applications of CP emitting materials.

Chiral Oligothiophenes with Remarkable Circularly Polarized Luminescence and Electroluminescence in Thin Films

“…A further source of artifacts is due to photoselection, which is strictly related to the experiment geometry and to the polarization of the exciting radiation [5] . More recently, evidence of the interference between luminescence anisotropy and linear birefringence has been reported, which leads to CPL with the observation of non‐reciprocal CPL [6] …”

“…[5] More recently,e videnceo ft he interference between luminescence anisotropy and linear birefringence hasb een reported,w hich leads to CPL with the observation of non-reciprocal CPL. [6] In recent years CPL hasf ound appealinga pplicationsi no rganic optoelectronics and photonics. [7] In order to obtain circularly polarized electroluminescence (CPEL), the final emitter must be chiral and non-racemic, which can be obtained with several strategies.…”

“…It was able not only to improvet he OLED performance by promoting the injection of electrons into the activel ayer, but also to partially absorb the light directed to or reflected by the back electrode. [6,18] We selected 1,3,5-tris (1-phenyl-1H-benzo[d]imidazol-2-yl)benzene (TPBi), having good electron-trans- porting and hole-blocking properties. [19] Furthermore, TPBi showedo rthogonal solubility with respect to 4:t he first is soluble in CH 3 OH, the second in CHCl 3 .…”

500‐Fold Amplification of Small Molecule Circularly Polarised Luminescence through Circularly Polarised FRET

“…In such systems, the excitation of donors that incorporate heavy atoms permits intersystem crossing to triplet states, and their chirality results in the generation of spin‐polarised triplet excitons which ultimately enhance the g PL of chiral acceptors [18] . For small molecules which self‐assemble into anisotropic aggregates, Zinna, Di Bari and co‐workers have shown it is possible to achieve high | g PL | (10 −2 ) through a coupling of linear fluorescence anisotropy and linear birefringence [20] . Alternatively, efforts have been made to induce chiroptical effects into otherwise achiral molecules, primarily through the incorporation of carefully selected achiral molecules into chiral media.…”

“…[18] For small molecules which self-assemble into anisotropic aggregates, Zinna, Di Bari and co-workers have shown it is possible to achieve high j g PL j (10 À2 ) through a coupling of linear fluorescence anisotropy and linear birefringence. [20] Alternatively, efforts have been made to induce chiroptical effects into otherwise achiral molecules, primarily through the incorporation of carefully selected achiral molecules into chiral media. For example, Zhu, Liu et al demonstrated the induction of CPL (j g PL j % 10 À2 ) of achiral small molecule luminophores when embedded within the chiral voids of a cubic, self-assembled cyclodextrin metal organic framework.…”