Design and growth of dendritic Cu_2-xSe and bunchy CuSe hierarchical crystalline aggregations

Dendritic nanocrystals of copper selenide were fabricated in situ for the first time by using alcohol as the solvent. Cu_2-xSe films composed of hierarchically ordered dendritic nanostructures were prepared on Cu substrates at a rather moderate temperature of 190-200 °C for just 1-3 h, while bunchy CuSe nanostructures could be further constructed above the Cu_2-xSe dendrites by prolonging the reaction time of solvothermal growth with ethanol as the solvent. The resulting Cu_2-xSe nanodendrites display highly symmetric corolitic morphology while the bunchy CuSe aggregations show particular nanostructures with a pronounced trunk and actinomorphic multi-branches. It is also found that the dendritic structures of crystalline Cu_2-xSe could never be obtained when the reaction temperature is less than 190 °C, while the temperature needed is 160 °C for Ag ₂Se nanodendrites and higher than 220 °C for CdSe nanodendrites. These copper selenide nanostructures with hierarchically ordered 3-dimensional (3D) framework exhibited good absorbance and photoluminescence (PL) property and could bear potential applications in solar cell devices in the future.