Improving Photocurrent Generation: Supramolecularly and Covalently Functionalized Single‐Wall Carbon Nanotubes–Polymer/Porphyrin Donor–Acceptor Nanohybrids

Electrostatic interactions: A versatile donor–acceptor system has been constructed by exploiting the electrostatic interactions between covalently and noncovalently polymer‐functionalized SWNTs (i.e., SWNT–PVBTAn+ and SWNT/PVBTAn+) and porphyrins (i.e., H2P8− or ZnP8−). The nanohybrids thus formed afford long‐lived radical–ion pairs and valuable photocurrent conversions (see figure). Novel nanohybrids based on covalently and noncovalently functionalized single‐wall carbon nanotubes (SWNTs) have been prepared and assembled for the construction of photoactive electrodes. Polymer‐grafted SWNTs were synthesized by free‐radical polymerization of (vinylbenzyl)trimethylammonium chloride. Poly[(vinylbenzyl)trimethylammonium chloride] (PVBTAn+) was also noncovalently wrapped around SWNTs to form stable, positively charged SWNT/PVBTAn+ suspensions in water. Versatile donor–acceptor nanohybrids were prepared by using the electrostatic/van der Waals interactions between covalent SWNT–PVBTAn+ and/or noncovalent SWNT/PVBTAn+ and porphyrins (H2P8− and/or ZnP8−). Several spectroscopic, microscopic, transient, and photoelectrochemical measurements were taken to characterize the resulting supramolecular complexes. Photoexcitation of the nanohybrids afforded long‐lived radical ion pairs with lifetimes as long as 2.2 μs. In the final part, photoactive electrodes were constructed by using a layer‐by‐layer technique on an indium tin oxide covered glass support. Photocurrent measurements gave remarkable internal photon‐to‐current efficiencies of 3.81 and 9.90 % for the covalent ZnP8−/SWNT–PVBTAn+ and noncovalent ZnP8−/SWNT/PVBTAn+ complex, respectively, when a potential of 0.5 V was applied. Electrostatic interactions: A versatile donor–acceptor system has been constructed by exploiting the electrostatic interactions between covalently and noncovalently polymer‐functionalized SWNTs (i.e., SWNT–PVBTAn+ and SWNT/PVBTAn+) and porphyrins (i.e., H2P8− or ZnP8−). The nanohybrids thus formed afford long‐lived radical–ion pairs and valuable photocurrent conversions (see figure).