Fully conjugated block copolymers, consisting of an electron donor and an electron acceptor block, can be designed for high performing organic photovoltaic devices. We have recently demonstrated block copolymer photovoltaic devices with approximately 3% power conversion efficiency using the fully conjugated block copolymer poly(3-hexylthiophene)−block−poly-((9,9-dioctylfluorene)-2,7-diyl-alt-[4,7- bis(thiophen-5-yl)-2,1,3-benzothiadiazole]-2’,2"-diyl) (P3HT-b-PFTBT) as the active material. Block copolymer device performance outperforms devices that contain P3HT/PFTBT blends by a factor of three due to the self-assembly of P3HT-b-PFTBT into alternating donor and acceptor domains. Furthermore, incorporating the donor-acceptor interface within the chemical structure enables model studies of charge and energy transfer. To this end, we have synthesized a new block copolymer by substituting a carbazole moiety in place of fluorene in PFTBT, making P3HT-b-PCDTBT. This small adjustment of the chemical structure increases the highest occupied molecular orbital (HOMO) level of the electron acceptor up from ~5.8 in PFTBT to ~5.5 eV in PCDTBT. We can further modify the structure to enable solution photoluminescence studies resulting in a similar block copolymer, P3HT-b-PCT6BT, where PCT6BT contains additional hexyl side chains on the thienyl units to enhance solubility. We determined the relative absorbance and photoluminescence fractions of P3HT and PCT6BT in the block copolymer through superposition of homopolymer spectra. The photoluminescence data from block copolymers in solution suggest significant energy transfer from P3HT to PFT6BT and PCT6BT, indicating that a mechanism for charge photogeneration in P3HT-b-PFTBT block copolymers includes energy transfer from the donor to the acceptor and hole transfer from the acceptor to the donor.