The outer walls of double wall carbon nanotubes (DWCNTs) have been selectively functionalized with different substituted perylenediimides (PDIs) leaving the inner walls intact. The spacer connecting DWCNT and PDI, and the PDI substitution position has been varied to visualize the DWCNT-PDI interactions in the hybrids. Evidence of outer wall functionalization and degree of PDI substitution on DWCNT were arrived from HR-TEM, AFM, IR, TGA, XPS and Raman techniques while nanotube-photosentisizer interactions were probed from studies involving optical absorbance and emission, and electrochemical techniques. Fine-tuning of the electronic states of PDI in the hybrids was possible with the present covalent approach. The fluorescence of PDI in the hybrids was found to be quenched (60-70%) due to interactions with DWCNT. Further, femtosecond transient absorption and photocatalytic electron pooling studies were performed to seek evidence of charge separation in these hybrids. In agreement with earlier studies, evidence of charge separation from the transient studies was bleak, and accordingly, yields of photocatalytic electron pooling were much lower than those reported earlier for fullerene and single wall carbon nanotube based hybrids. The present study is suggestive of further tuning of donor-acceptor energy levels in DWCNT derived hybrids for efficient charge separation and stabilization.