Liquid crystals in photovoltaics: a new generation of organic photovoltaics

Abstract

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

Mesogenic complementary absorbing dyads based on porphyrin and perylene units

“…Thus, the DLC materials exhibiting ordered columnar phases have application potential as one-dimensional charge carrier transport systems [28]. So far, the 4-8% PCE of bilayer solar cells and BHJ solar cells using DLC materials have been achieved [22].…”

“…Calamitic and discotic liquid crystals (DLCs), featuring long exciton diffusion length and high chargecarrier mobility, have been considered as a new generation of organic photovoltaics [22]. The conventional DLC molecules comprise a planar rigid core and several aliphatic chains, normally through ether, thioether, or ester bonds peripherally attached to the cores [23][24][25].…”

Cancer, Photodynamic Therapy and Porphyrin-Type Derivatives

“…2). It has been well established that porphyrin-type compounds can have applications in several fields and devices, like solar cells and electron transfer processes, as oxidative catalysts, (Sheldon 1994, Simões et al 2016) as sensors, (Paolesse et al 2017) semiconductors and superconductors, (Jian et al 1998) liquid crystals, (Kumar and Kumar 2017) biocides (fungicides and insecticides) (Carré et al 1999, Amor et al 1998) but significantly it is in Medicine, acting against cancer cells (photodynamic therapy -PDT) and more recently in the photo-inactivation of microorganisms (photodynamic inactivation -PDI), that such compounds can contribute for a better life to human beings (Bonnett 2000, Almeida et al 2011.…”

Functional liquid-crystalline polymers and supramolecular liquid crystals

“…For example, LC polymers 6 and 7 bearing electroactive moieties are obtained by using π-conjugated molecules as mesogenic units. [15][16][17][18] The introduction of azobenzene moieties into the side chain of LC polymers leads to the development of photoresponsive optical systems 8 and photo-actuators. 25,26 Anisotropic two-dimensional (2D) ion-conductive materials 9 and 10 are achieved by incorporation of ionic moieties or oligo(oxyethylene) units complexed with inorganic salts in the spacer or the terminal group of the side-chain LC polymers.…”

“…For example, functional main-chain LC polymers 5 have been prepared to exhibit electron conductivities and luminescence properties. 11,12 Photofunctional, 13,14 electro-active, [15][16][17][18] and ion-active [19][20][21][22][23][24] groups have been incorporated into the side chains of LC polymers. For example, LC polymers 6 and 7 bearing electroactive moieties are obtained by using π-conjugated molecules as mesogenic units.…”