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The impact on chiral aggregation in solution processed and thermally annealed thin films of two indolenine and one anilino squaraines with chiral (S)‐citronellyl functionalization at the nitrogen of the squaraine backbone is investigated. A pseudo polymorphic crystal structure is obtained for one of the indolenine squaraines, but thin films of both compounds are basically non‐aggregated and truly isotropic as evidenced by spectroscopic ellipsometry. The anilino squaraine coalesces and readily aggregates to circular dichroic but discontinuous thin films. The extent of circular dichroism correlates with the morphology of the samples, which is quantified by Mueller matrix polarimetry in combination with atomic force microscopy. The shape of the CD spectra reinforces the hybrid Frenkel and charge‐transfer excitonic nature of the characteristic double hump signatures within unpolarized absorbance spectra of previously investigated non‐chiral anilino squaraines with linear alkyl chain functionalization. Such excitonic CD offers an additional design parameter for next‐generation opto‐electronic devices. [ABSTRACT FROM AUTHOR]

An enantiomerically pure (R)‐2‐methylpyrrolidine‐based anilino squaraine crystallizes in two chiral polymorphs adopting a monoclinic C2 and an orthorhombic P212121 structure, respectively. By various thin‐film preparation techniques, a control of the polymorph formation is targeted. The local texture of the resulting textured thin films is connected to the corresponding optical properties. Special attention is paid to an unusual Davydov splitting, the anisotropic chiroptical response arising from preferred out‐of‐plane orientation of the crystallites, and the impact of the polymorph specific excitonic coupling. [ABSTRACT FROM AUTHOR]

A facile route to soft matter self‐powered bulk heterojunction photodiode detectors sensitive to the circular polarization state of light is shown based on the intrinsic excitonic circular dichroism of the photoactive layer blend. As light detecting materials, enantiopure semiconducting small molecular squaraine derivates of opposite handedness are employed. Via Mueller matrix ellipsometry, the circular dichroism is proven to be of H‐type excitonic nature and not originating from mesoscopic structural ordering. Within the green spectral range, the photodiodes convert circular polarized light into a handedness‐dependent photocurrent with a maximum dissymmetry factor of ±0.1 corresponding to 5% overall efficiency for the polarization discrimination under short circuit conditions. On the basis of transfer matrix optical simulations, it is rationalized that the optical dissymmetry fully translates into a photocurrent dissymmetry for ease of device design. Thereby, the photodiode's ability to efficiently distinguish between left and right circularly polarized light without the use of external optical elements and voltage bias is demonstrated. This allows a straightforward and sustainable future design of flexible, lightweight, and compact integrated platforms for chiroptical imaging and sensing. [ABSTRACT FROM AUTHOR]