The optical properties of perovskite materials are spin dependent. Therefore, tuning the spin-exchange energy in perovskite materials can provide a way towards improving their photovoltaic and light-emission performances. In this study, the effect of an externally applied magnetic field on the magneto-photocurrent of hybrid-perovskite-based devices was investigated. We show that a magnetic field can be used to tune the short-range exchange energy of excited states, which results in a negative magneto-photocurrent. Besides, doping perovskite with manganese provides an additional way to tune the long-range spin-exchange energy between the excited states through the formation of polarons. This can lead to an increase of the performance of perovskite-based optoelectronic devices.