Information on TU Dortmund in general is here and here. TU Dortmund is a Technical University which means that the emphasis is on technical subjects (science and engineering). Information on the Department of Computer Science (which was one of the first such departments, founded in 1972) can be found here. The research groups of the department are listed here.
The department is ranked 1st (joint with TH Karlsruhe) out of the 84 CS departments in Germany according to the ranking of the DFG (German Science Foundation), which ranks based on the amount of funding received from the DFG, cf Table A-10, column INF on page 166 in here (see here for more info on that ranking).
TU Dortmund has several associated research institutes including the Fraunhofer Institute for Software and Systems Technology (ISST). At the TU Dortmund campus there is also the Technologie Zentrum Dortmund which is apparently one of the five largest areas for technology startups in Europe, together with those in Stockholm, Berlin, Cambridge, and Sophia Antipolis.