The investigated Zn-paddle wheel SURMOF-2 derivative utilized Pd-porphyrinoid linkers (Pd-PP-SURMOF, see Figure ). As parent SURMOF-2, this structure is also a square lattice inplane and layers are stacked in the AAAA fashion. Such a system results in fairly dispersionless bands of the electronic structure (see Figure ), however, zoom-in to the conduction and valence bands reveals dispersion of a few meV. This value corresponds to a mobility of about 0.003 cm 2 V -1 s -1 , which at that time was larger than for any other MOF. This MOF exhibits an indirect band gap, which should result in suppressed electron-hole recombination and improved photovoltaic properties in such organic-semiconductor based devices. . Bands are fairly flat, however, small out-of-plane dispersion occurs in the direction perpendicular to the layers. The dispersion is in the limit of a couple of meV. Pictures of structures made with VESTA. The photovoltaic efficiency of the reported PP-SURMOF amounts to only 0.2%, and is thus far too low for realizing a competitive device. Another issue is the absorbance of the PP itself: the strongly absorbing Soret band is in the ultraviolet, while the Q bands, which are located in the visible spectrum, are only weakly absorbing. PP functionalization can strongly enhance the absorbance of the Q bands. Among the large number of possibilities, three particularly interesting ones have been identified by combining rational design with computational screening. (1) Distorting the planarity alters the selection rules and, thus, enhances the intensity of the Q bands. This can be achieved by bromination of the PP core (twisted octabromo porphyrin). ( ) The π-conjugation of the PP can be extended by adding a phenyl-acetylene (PA) group. ( ) The π-system can be affected by the presence of electron-withdrawing fluorinated phenyl substituents. All three strategies show an effect on the isolated PP linker molecules, in particular, the Q band intensity increases. Incorporated to a PP-SURMOF, these three linkers, however, show very different absorbance. This can, again, be attributed to the proximity effect.