Arylacetylene-substituted naphthalene diimides with dual functions: optical waveguides and n-type semiconductors

Abstract

New arylacetylene-substituted naphthalene diimides (NDIs) 1-6, with both light-emitting and semiconducting functions, are reported. Among them, the crystal structure of 1 was determined. On the basis of their reduction potentials and thin-film absorption spectra, the HOMO/LUMO energies of these modified NDIs were estimated. The results reveal that their HOMO/LUMO energies are slightly affected by the flanking aryl groups. The emission colors of these NDIs vary from green to red, and interestingly, they show aggregation-induced emission enhancement behavior with fluorescence quantum yields reaching 9.86% in the solid state. Microrods of 1, 3, and 5 show typical optical wave-guiding behavior with relatively low optical-loss coefficients. Organic field-effect transistors with thin films of these NDIs were fabricated with conventional techniques. The results indicate that thin films of 2, 4, and 6, with long and branched alkyl chains, show air-stable n-type semiconducting properties with electron mobilities of up to 0.035 cm(2) V(-1) s(-1) after thermal annealing, whereas 1, 3, and 5, with short alkyl chains, behave as n-type semiconductors under a nitrogen atmosphere with electron mobilities of up to 0.075 cm(2) V(-1) s(-1) after thermal annealing.

Keywords: arylacetylene; naphthalene diimide; optical waveguide; organic semiconductors.