Volker Rabens is now “seit 2013 Wissenschaftlicher Mitarbeiter am Lehrstuhl für Neues Testament (Prof. Dr. Karl-Wilhelm Niebuhr) an der Friedrich-Schiller-Universität Jena”. In his research he is mainly interested in Ethics, Pneumatology, Paul, John, 1 Peter, Early Judaism (Philo included), and hermeneutics. His List of publications, with – most graciously – a lot of links for downloading many of his works, is available here: Rabens Bibliography.
Here is a list of what I found directly related to Philo:
Volker Rabens, ‘Geistes-Geschichte. Die Rede vom Geist im Horizont der Griechisch-romischen und judisch-hellenistischen Literatur,’ Zeitschrift fur Neues Testament 25 Jahrgang 13 (2010):46-55.
Volker Rabens, ‘Johannine Perspectives on Ethical Enabling in the Context of Stoic and Philonic Ethics,’ In J. van der Watt and R. Zimmermann (eds.), Rethinking the Ethics of John: “Implicit Ethics” in the Johannine Writings (Kontexte und Normen neutestamentlicher Ethik / Contexts and Norms of New Testament Ethics III; WUNT I/291; Tübingen: Mohr Siebeck, 2012): 114-139.
Volker Rabens, ‘Philo’s Attractive Ethics on the “Religious Market” of Ancient Alexandria,’ In Peter Wick and Volker Rabens, eds., Religions and Trade: Religious Formation, Transformation and Cross-Cultural Exchange between East and West. (Dynamics in the History of Religions 5; Leiden: Brill, 2013 (Copyrighted:2014): 333-355.
Volker Rabens, Pneuma and the Beholding of God: Reading Paul in the Context of Philonic Mystical Traditions,’ In Jörg Frey and Jack Levison eds., The Holy Spirit, Inspiration, and the Cultures of Antiquity. Multidisciplinary Perspectives (Ekstasis: Religious Experience from Antiquity to the Middle Ages 5; Berlin-New York; DeGruyter – forthcoming.) I am a little confused here as prof. Rabens gives the title of the volume as The Historical origins of the Holy Spirit; the other title here is taken from the DeGruyter website.
One should probably also mention his dissertation; though this focuses primarily on Paul, it also has a few pages on Philo as part of possible background material:
Volker Rabens, The Holy Spirit and Ethics in Paul: Transformation and Empowering for Religious-Ethical Life, Second Revised Edition. Minneapolis: Fortress Press, 2014.