Poly(3-hexylthiophene) (P3HT) is a versatile polymer that has been deeply studied as a material for electronic devices and also for organic solar cells. This study is a recompilation of the molar mass and polydispersity dependence studies on its charge carrier mobility, crystallinity and PCBM based solar cells. Through the examination of different works, it has been demonstrated the necessity of increasing annealing temperature along molar mass in order to obtain better values of power conversion efficiency. Due to the probable polymer degradation, thermal analysis must be performed in order to approach the observed trend of increasing charge carrier mobility along with molar mass. The maximum power conversion efficiency (PCE) value reported for P3HT: PCBM device is 4.42% for a P3HT with number average molar mass M-n of 43 kDa and polydispersity index (PDI) of 2.1. This latter parameter was found to play an important role in the solar cell performance, and it was observed that a narrow molar mass distribution is not always desirable, especially for polymers with high molar masses. (C) 2017 Elsevier B.V. All rights reserved.