Controllable Synthesis and Effects of Porphyrin Copper Nanostructures on Photoelectric Properties

A variety of organic semiconductor nanostructures have been already reported for photoelectric applications; however, there are a few systematic studies on the dependence of their photocurrent on nanostructures. Here, 0D, 1D, 2D, and 3D nanostructures of 5,10,15,20-tetrakis(4-carboxyphenyl) porphyrin copper (CuTCPP) are successfully constructed via liquid-phase chemical methods. Structural characterization shows that 0D and 1D nanostructures should result from the π–π stacking of CuTCPP molecules, while 2D and 3D ones are mainly from the in-plane aggregation via the linkage of −COOH with the Cu ion. The photoelectric properties of CuTCPP-based nanostructures are investigated to evaluate the effect of shape, size, and structure. A huge difference in photocurrent response is found, as compared to the raw material (0.09 μA/cm2) and 0D (0.17 μA/cm2), 1D (2.24 μA/cm2), 2D (0.4 μA/cm2), and 3D (0.93 μA/cm2) nanostructures. Further study reveals that the 1D nanostructure exhibits the lowest impedance and the longest exciton lifetime, strongly indicating that the photocurrent of the metal porphyrin nanostructure should be mainly limited in an in-plane exciton with a shorter lifetime than in an intermolecular one. This work provides a clear strategy to design molecule-based photoelectric nanomaterials.