The trapping of photobiologically produced dienes will likely be in alkane solvents. As the dilution of dienes reduces the yields of dimerization, we explored raising the photosensitizer loading, which improved the conversions, until an optimal loading is reached after which the conversion decreased. The results support further development of our two-step photobiological-photochemical production of jet fuel hydrocarbons via small 1,3-dienes, with a special focus on isoprene as the most suitable diene as it is readily available photobiologically and known to undergo a highly efficient photosensitized dimerization.