Dye-sensitized solar cells (DSCs) offer the possibilities to design solar cells with a large flexibility in shape, color, and transparency. DSC research groups have been established around the world with biggest activities in Europe, Japan, Korea, China, and Australia. The sun emits light with a range of wavelengths from the ultraviolet and visible to the infrared. It peaks in the visible, resembling the spectrum of a blackbody at a temperature of 5760 K. It is, however, influenced by atmospheric absorption and the position of the sun. The advent of heteroleptic ruthenium complexes furnished with an antenna function has taken the performance of the DSC to a new level. Two examples of these dyes are Z991 and C101. Compared with the classical DSC Ru dyes, their extinction coefficients are higher and the spectral response is shifted to the red. The positions of the energy levels at the oxide/dye/electrolyte interface are fundamentally important to the function of the DSC.

The indolocarbazoles are an important class of nitrogen heterocycles which has evolved significantly in recent years, with numerous studies focusing on their diverse biological effects, or targeting new materials with potential applications in organic electronics. This review aims at providing a broad survey of the chemistry and properties of indolocarbazoles from an interdisciplinary point of view, with particular emphasis on practical synthetic aspects, as well as certain topics which have not been previously accounted for in detail, such as the occurrence, formation, biological activities, and metabolism of indolo[3,2- b]carbazoles. The literature of the past decade forms the basis of the text, which is further supplemented with older key references.