Applications of Metal-Free 1,2,4-Triazole Derivatives in Materials Science

The 1,2,4-triazole system has shown excellent electron-transport and hole-blocking properties owing to its highly electron-deficient nature. Accordingly, a large number of 1,2,4-triazole derivatives have been described as having a wide variety of uses in materials science. Triazoles are widely used in transition-metal complexes or metal-organic frameworks (MOFs), but metal-free 1,2,4-triazole derivatives have also exhibited interesting and useful properties as materials. The use of these derivatives, either as small molecules or polymers, in light-emitting devices has allowed the fabrication of OLEDs, PHOLEDs and PLEDs with excellent properties. Other materials have exhibited liquid crystalline or optical waveguide behavior or have found applications in PEMFCs, organic photovoltaic cells and data storage devices. The aim of this review is to discuss the most important metal-free derivatives bearing 1,2,4- triazole moieties with applications as organic materials.