Recently, Ruddlesden-Popper 2D perovskites (RPPs) solar cells and Light-Emitting Diodes (LED) have shown promising eciencies and improved stability in comparison to 3D halide perovskites. Here, the exciton recombination dynamics is investigated at room temperature in pure phase RPPs crystals (C 6 H 5 C 2 H 4 NH 3) 2 (CH 3 NH 3) n1 Pb n I 3n+1 (n=1, 2, 3 and 4) by time-resolved photoluminescence in a large range of power excitations. As the number of perovskite layers increases, we detect the presence of an increasing fraction of out-of-equilibrium free carriers just after photoexcitation, on a picosecond timescale, while the dynamics is characterized by the recombination of excitons with long lifetime spanning on several tens of nanoseconds. At low excitation power, the PL decays are non-exponential due to defect-assisted recombination. At high uence, defects are lled and many body interactions become important. Similarly to other 2D systems, Exciton-Exciton Annihilation (EEA) is then the dominant recombination path in a high density regime below the Mott transition.