In regioregular poly(3-hexylthiophene) /1-(3-methoxycarbonyl)propyl-1-phenyl-[6,6]-methanofullerene (RR P3HT/PCBM) bulk heterojunction structures the recombination features of photogenerated and of double injection charge carriers are compared. The investigations have been made using time-of-flight (TOF), charge extraction by linearly increasing voltage (CELIV), and double injection transient methods. In both cases when electric field is absent (photogeneration case) and in various electric fields (double injection case) the bimolecular recombination coefficient 10(3)/10(4) has been estimated times lower than Langevin's one (beta(L)). The weak dependence of beta on electric field was obtained and activation energy of beta lower than Of one was estimated. (c) 2005 Elsevier B.V. All rights reserved.