Solution-phase controlled synthesis of Cu₃NbSe₄ nanocrystals for optoelectronic applications

Cu₃MX₄ (M = V, Nb, and Ta; X = S, Se, and Te) compounds have recently emerged as greatly promising solar energy conversion materials due to their tailorable band gaps, high optical absorption coefficients, environmentally benign nature and comparatively abundant elements. However, solution synthesis of Cu₃NbSe₄ nanocrystals as a photoactive material for investigating their optoelectronic properties has not yet been reported. Herein, we present a facile synthesis of cube-shaped Cu₃NbSe₄ nanocrystals with high crystallinity, high uniformity and monodispersity. Studies of the formation process disclose that the reaction temperature, time and surface ligand play significant roles in determining the crystalline phase, size and morphology evolution of the Cu₃NbSe₄ nanocrystals. Excitingly, a Cu₃NbSe₄-based photodetector exhibits a high I_light/I_dark ratio of 35, fast response speeds of 0.3/0.1 s for rise/fall times and excellent stability, indicating its robust potential for application in electronics and optoelectronics.