Thin films of discotic liquid crystals and their applications

ABSTRACT

Discotic liquid crystals (DLCs) are considered as fascinating systems due to their unique property of self-assembly to yield different columnar structures. DLCs are organic semiconductors and create pathways for the development of numerous optical and electrical devices. The thin films of DLCs can be considered as low dimensional system which can exhibit remarkable optical and physical properties. In this article, we present a review on ultrathin films of some interesting DLC molecules at air–water and air–solid interfaces. The Langmuir monolayer and Langmuir–Blodgett films of DLC molecules are extensively studied. The ultrathin films of DLC molecules can yield highly anisotropic layer wherein the molecular orientation and aggregation can have large impact on the physicochemical properties of the film. Different surface phases with different molecular orientations as function of surface density and temperature can be obtained by forming the Langmuir monolayer of the DLC molecules at the air–water interface. The Langmuir monolayer in a particular phase can be deposited onto the active area of a device layer-by-layer by employing a highly controlled Langmuir–Blodgett technique. Here, we report some interesting results related on molecular orientation of the DLC molecules at different interfaces. Such aggregation of DLC molecules in ultrathin films may find applications in thin film-based electro-optical devices.

GRAPHICAL ABSTRACT

KEYWORDS:

• Discotic liquid crystals
• Langmuir monolayer
• Langmuir-Blodgett film
• alignment layers

Acknowledgments

We are thankful to Prof. Sandeep Kumar of Raman Research Institute for providing the DLC molecules and facilitating few important experimental tools for characterisation. Thanks are also due to University Grants Commission for Special Assistance Programme from 2009 to 2013. We acknowledge BITS Pilani for providing fellowship to research scholars, CK and KC.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

We acknowledge BITS Pilani for providing fellowship to research scholars, CK and KC.