Among aprotic solvents, it is found that solvents with higher polarity result in larger adsorption free energy for the dye and faster electron injection. Overall, these studies reveal that aprotic solvents with high solvent polarity (such as acetonitrile) yield more efficient solar cell devices. Solvent dye is a dye that is soluble in plastics or organic solvents. When it goes with an organic solvent the dyeing process occurs in a solution. As the molecules of solvent dyes have a very small polarity or none at all there is no ionization involved in the dyeing process as it does, say, with acid dyes. Solvent dyes are normally water insoluble. One commonly used organic solvent with solvent dyes that is non-polar is petrol. colored with the aid of solvent dyes. In the printing industry they go towards marking inkjet inks, inks and glass coloration. Textile printing is followed by the media industry where the solvent dyes are used for magazines and newspapers. Dyeing of plastics is another application which uses solvent dyes because of its chemical compatibility. In the plastics industry these dyes lend color to a number of solid materials like nylon, acetates, polyester, PVC, acrylics, PETP, PMMA, styrene monomers, polystyrene and other fiber. At the heart of every drop of paint, every thread of cloth, every bit of your brightly colored phone case is a pigment. Pigments are the compounds added to materials to give them color. This deceptively simple application has shaped our perception of the world via art, fashion, and even computer displays and medicine. Pigments are used in paints, inks, plastic applications, fabrics, cosmetics, and food. Some of the earliest chemistry was to make and isolate pigments for paints, and pigment conservation is a focus for many modern researchers who identify and preserve artwork. Get to know pigments But what is a organic pigment, exactly? Analyzing and understanding the high performance pigment used in paintings is also vital to artwork restoration and preservation. Many pigments chemically, like coating and paints, react with ambient light and humidity, as well as harsher substances like soot and smoke from cigars or fireplaces. Pigments may oxidize, dissolve in acid or water, undergo phase transitions, react with the binders in the paint, or degrade.