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This article presents an overview of the developments in the field of organic photovoltaics (PVs) with liquid crystals (LCs). A brief introduction to the PV and LC fields is given first, followed by application of various LCs in organic PVs. Details of LCs used in bilayer solar cells, bulk heterojunction solar cells and dye-sensitized solar cells have been given. All the liquid crystalline materials used in PVs are structured and the efficiency of solar cells is tabulated. Finally, an outlook into the future of this newly emerging, fascinating and exciting field of self-organizing supramolecular LC PV research is provided. Polymer Journal (2017) 49, 85-111; doi:10.1038/pj.2016.109; published online 9 November 2016 INTRODUCTIONFor the sustainable growth of the global economy, availability of cheap energy is essential. Our energy demand is increasing continuously to improve our lifestyle. At present, fossil energy sources are the primary sources for most of the world's current energy requirements and only a little is provided by hydropower, nuclear energy and biomass. The exponential growth of carbon dioxide level in the atmosphere owing to the burning of fossil fuels is leading to the threat of a universal climate change. Moreover, there will be limited availability of conventional energy sources in the long term. Future energy demand cannot be met with conventional sources of energy. Nuclear energy sources are one of the promising energy sources, but owing to their associated hazardousness and cost effectiveness, these energy sources does not appear to be socially acceptable universally. Moreover, nuclear fuel is also limited to tackle gigantic demand of energy. Despite several efforts, the problem of energy provision around the world remains unsolved, and there is a great need of finding alternative clean energy sources. To solve the energy crisis of the globe, exploitation of solar energy is undoubtedly the best answer. It is the most abundant inexhaustible source of regenerative energy. It is known since the evolution of life on the Earth that Mother Nature generates chemical energy from solar energy via photosynthesis. The supply of energy by Sun on Earth in an hour is more than that we use in a year. Therefore, only a fraction of solar energy is required to overcome our all energy requirements, if it can be converted to electric energy efficiently. The device that is developed to convert solar energy into electrical energy is known as photovoltaic (PV) solar cell.During the past 60 years, PV energy has been used as a promising candidate for energy devices because it is abundant, inexhaustible, cheap, straight to production ability and pollution-free that does not raise the green-house gases. The PV effect involves the generation of a photocurrent and photovoltage on absorption of light photons in a semiconductor. The three-step process, which is an

Gold nanoparticles fully covered with triphenylene-based discotic liquid crystals (DLCs) were synthesized and dispersed in a columnar matrix. The thermophysical properties of these nanocomposites, studied using polarizing optical microscopy, differential scanning calorimetry and small angle X-ray diffraction studies (SAXS), confirm their insertion into the columnar matrix. The presence of the gold nanoparticles in the triphenylene-based DLCs does not disturb the nature of the mesophase other than altering the transition temperatures. We propose that the gold nanoparticles are distributed between the domain gaps of the DLCs in random disordered manner. Interestingly the DC conductivity measurements show an enhancement of the electrical conductivity by more than a million times upon doping of the discotic liquid crystals with the triphenylene-capped nanoparticles under ambient conditions.

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The synthesis, optical properties and thermal behaviour of three novel non-conventional 3,4,9,10-tetrasubstituted perylene-based discotic oligomers are reported for the first time consisting of a perylene core attached to which are four 4-cyanobiphenyl, triphenylene and cholesteryl units via flexible alkyl spacers. All the oligomers self-assemble into a mesophase and exhibit excellent fluorescence emission properties making them suitable for various opto-electronic applications.

Graphene is inherently sensitive to vicinal dielectrics and local charge distributions, a property that can be probed by the position of the Dirac point in graphene field‐effect transistors. Exploiting this as a useful sensing principle requires selectivity; however, graphene itself exhibits no molecule‐specific interaction. Complementarily, metal–organic frameworks can be tailored to selective adsorption of specific molecular species. Here, a selective ethanol sensor is demonstrated by growing a surface‐mounted metal–organic framework (SURMOF) directly onto graphene field‐effect transistors (GFETs). Unprecedented shifts of the Dirac point, as large as 15 V, are observed when the SURMOF/GFET is exposed to ethanol, while a vanishingly small response is observed for isopropanol, methanol, and other constituents of the air, including water. The synthesis and conditioning of the hybrid materials sensor with its functional characteristics are described and a model is proposed to explain the origin, magnitude, and direction of the Dirac point voltage shift. Tailoring multiple SURMOFs to adsorb specific gases on an array of such devices thus generates a versatile, selective, and highly sensitive platform for sensing applications.