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.