Rapid Microwave-Enhanced Solvothermal Process for Synthesis of CuInSe2 Particles and Its Morphologic Manipulation

CuInSe2 nanoparticles are prepared using a microwave-assisted solvothermal method with ethylenediamine as a solvent. The morphology of the as-prepared CuInSe2 nanoparticles has been successful manipulated by controlling the morphology of selenium seeds. We achieved this through a systematic treatment of selenium powders before the addition of indium and copper precursors. This pretreatment of selenium powders, under microwave heating, converts the morphologies of selenium seed from spherical to nanorod. As a result, this nanorod morphology of selenium seeds are responsible for the formation of crystalline CuInSe2 particles with rodlike morphology, while the crystalline CuInSe2 particles with platelike morphology are obtained without pretreatment of selenium powders. The XRD data and SEM images show that pure chalcopyrite CuInSe2 particles with good crystallinity are obtained with the pretreatment of selenium and ethylenediamine mixture in the microwave heating for 30 min and followed by further microwave-enhanced reaction with indium and copper precursors for 30 min. We proposed the reaction mechanism based on XRD and SEM data, which includes the intermediate products. The Raman spectrum of the chalcopyrite CuInSe2 nanoparticle shows an intense peak at 175 cm(-1) corresponds to the A(l) phonon mode of tetragonal CuInSe2 chalcopyrite. The compositions of the products consistent very well with their nominal value are confirmed by energy-dispersive X-ray analysis.