Effects of Size on the Optical Properties of Organic Semiconductors: Copper (II) Phthalocyanine Nanoparticles

摘要

Organic materials are of great interest for use as electronic and optoelectronic devices. Currently, solar cells are in limited use, due to their relatively high cost. Solar cells based on organic semiconductors are promising as low-cost alternatives to current technologies; for example, low cost printed solar cells may be possible. However, significant frequency ranges in the solar spectrum are not absorbed. Expanding the absorption-spectrum bandwidth for the organic materials by varying the band gap can lead to improved efficiency for solar cells based on organic semiconductor inks. Here we test the possibility of using nanopariicles with different sizes to increase the absorption efficiency. Copper Phthalocyanine (CuPc) nanoparticles have been prepared by a Liquid-Liquid Interface Recrystallization Technique (LLIRCT), and deposited on substrates using a dip-coater at room temperature. The size of the nanoparticles is measured by transmission electron microscopy (TEM). Particle size and morphology are mainly determined by the preparation time. Optical proprieties were measured using UV-VIS spectroscopy from 350 to 1000 nm. The spectra show a shift in the peak positions as the panicles become smaller. The band gap increases with the particle size.