Fabrication of vertically aligned CuInSe2 nanorod arrays by template-assisted mechanical approach

A facile, low cost, and vacuum free method for fabricating vertically aligned copper indium diselenide (CuInSe2) nanorod (NR) arrays from pre-synthesized CuInSe2 nanoparticles (NPs) by mechanical approach using porous anodic aluminum oxide (AAO) as a template was demonstrated. This approach utilizes a rubbing technique to fill CuInSe2 NPs suspension into AAO template. X-ray diffraction and Raman spectroscopy study is employed to confirm the phase of CuInSe2 NPs before and after the formation of NRs. The polycrystallinity and composition of NRs are confirmed by using transmission electron microscopy. Optical studies of CuInSe2 NPs film reveal a reflectance of ∼9.8% while a significant reduction of the reflectance to ∼1.2% is observed after the formation of CuInSe2 NR arrays. The observed low reflectance behavior is attributed to a concept of gradual refractive index with vertical array structures. From differential reflectance spectra of CuInSe2 NRs, a band gap of ∼1.01 eV was observed, which is identical to its bulk value.