[en] Highlights: • Time-resolved absorption spectroscopy of polarons and polaron pairs in rr-P3HT 10 nm thin layers. • Coherent up/down conversion between polaron pairs and polarons up to ca 5 ps. • Bimolecular collision of polaron pairs driven by 1-D diffusion for longer times. On the basis of the analysis of the experimental data of the transient absorption spectroscopy of thin films of regioregular poly(3-hexyl thiophene) we suggest a mechanism of the polaron pairs decay based on the coherent up and down conversion cycling between hot polaron pairs and free polarons. Compared to previously adopted models, based on single molecular processes or bimolecular collisions, the suggested model reproduced well both the polaron pairs and polaron population kinetics at short time after photoexcitation. For longer times, when the polaron pairs are already thermalized, they decay via 1-D diffusion limited bi-molecular collision processes.