Photoconductivity of self-assembled nanotapes made from meso-tri(4-sulfonatophenyl)monophenylporphine

meso-Tri(4-sulfonatophenyl)monophenylporphine (TPPS 3 ) has one fewer sulfonate group than meso-tetra(4-sulfonatophenyl)porphine (TPPS 4 ), which has been shown to form well-defined, photoelectronically active nanorods. TPPS 3 , when deposited via immersion and spin-drying, forms tapelike aggregates of two distinct heights. The larger width of these nanotapes (compared to TPPS 4 nanorods) is expected from the smaller charge of the monomer when it is dissolved in acidic solution. The deposition of nanotapes onto a substrate can be patterned to a limited extent by scratching the substrate prior to aggregation. The nanotapes exhibit photoconductive properties very similar to those of TPPS 4 nanorods, including growth of photoconductivity over hundreds of seconds, as well as photovoltaic activity with trainable polarity. However, they show a stronger memory of the slow growth of photoconductivity. The quantum efficiency of photoconductivity is approximately 10 times lower than that for TPPS 4 nanorods.