Taking these various experimental observations and DFT calculations together, we suggest that the dramatic difference in catalytic activity for crystalline and amorphous TBAP might be explained, at least in part, by restricted charge/exciton transport in the amorphous material to the active sites on the catalyst surface. While the exciton quenching kinetics by the hole scavenger between amorphous TBAP and TBAP-α appear to be similar, it is possible that transfer of a subsequent electron or electron polaron to a Pt active site is aided by interlayer conjugation in the crystalline HOF, which does not exist in the amorphous analogue. Materials with a higher degree of order and closer π-π stacking have been shown previously to have higher charge-carrier mobilities; for example, in conjugated polymers such as poly(thiophenethieno[3,2-b]thiophene) and poly(cyclopentadithiophene-benzothiadiazole). Given this apparent benefit of extended π-stacked pyrene units, the low activity of TPyP-α, which has an overlap close to that of TBAP-α (0.86 vs 0.91) is somewhat surprising. It is possible that in the case of TPyP-α, inefficient hole scavenging (as observed by TCSPC) prevents efficient generation of polarons from excitons reducing the amount of hydrogen that can be produced. Thus, any potential increase in charge-carrier mobility due to the packing of TPyP-α in the crystal is less relevant due to the low quantity of polarons generated