The progress of materials science depends critically on the access to advanced characterization methods. During the last decades there has been an almost revolutionary development of modern X-ray based tools. We are today at a turning point in the development of synchrotron radiation based electron spectroscopy, where the program of the PI has maintained a leading position since 20 years. New techniques are evolving parallel to the development of a new generation of ultra-brilliant synchrotron radiation (SR) facilities. Electron spectroscopy is one of the most important techniques for the advancement of materials science and is one of the corner stones for the research at SR facilities. It is of highest priority to introduce new types of instruments to push the spectroscopy into new domains of time, spatial, energy and angular resolution.We have recently accomplished a break-through in this field with a new type of electron analyzer, the ArTOF instrument, capable of increasing the energy resolution down to the micro-eV range with a simultaneous increase of the transmission of almost three orders of magnitude, compared to the earlier instruments. In addition the emission angles of all electrons are determined, with high precision and within a wide cone. This allows us to obtain three dimensional electronic structure information in real time. The present ERC proposal defines an ambitious program to fully exploit the new possibilities in urgent fields of research: In situ time resolved electronic band structure of organic crystals for electronic applications, time resolved studies of 3D band structure of solids and new 2D materials (graphene, topological insulators), electron structure and dynamics of materials for solar cell applications, and in other important research fields. The research program will also adapt the new technique to take advantage of new opportunities opened by emerging ultra-brilliant X-ray sources.