NOVELTY - Preparing a multi-element metal chalcogenide (I), comprises: (a) preparing (11) at least one container; (b) loading (12) one or more pure metal element powders, and/or one or more alloy powders together with a chalcogen into the container; (c) introducing an organic solvent into the container, where the organic solvent has a boiling point higher than 240 degrees C, and a pH value of 7-10; and (d) conducting (13) a synthesis process comprising heating pure metal element powders and/or the alloy powders, the chalcogen, and the organic solvent to a reaction temperature above 200 degrees C.    USE - (I) is useful for fabricating a sputtering target, and preparing a coating material adapted for an ink-printing process for forming a multi-element metal chalcogenide thin film (all claimed). (I) is useful in a semiconductor solar cell.    ADVANTAGE - The synthesis can be conducted under a normal pressure, and does not require high pressure operation condition. The product does not contain any halide ions, and is adapted for mass production. The mole ratios of Cu, In, Ga, and Se ingredients can be adjusted for improving the cell efficiency. (I) provides uniform-ingredient ink and sputtering target which are adapted for conducting a stable process and producing a high quality copper-indium-gallium-selenide (CIGS) thin film. The aryl or arylamine binders used in the process has a high boiling point, alkalescence, and a chelating ability, hence facilitates the preparation of a high purity (I) having no halide ions in a large scale. (I) is derived from simple substance powders of the metal elements. The ingredients of the thin film are controllable, uniform and homogeneous and the thin film does not require a selenization process, hence the method simplifies the production process, saves the production cost, and improves the yield of the CIGS thin film solar cells.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for:    (1) preparing a nanoscale multi-element metal chalcogenide powder, comprising: steps (a)-(d) as above per se; and forming the nanoscale multi-element metal chalcogenide powder by conducting a cooling down step, a precipitation step, a filtering step, a flushing step, and a drying step to the multi-element metal chalcogenide;    (2) fabricating a sputtering target, comprising: sintering and pressing the nanoscale multi-element metal chalcogenide powder; and    (3) preparing a coating material adapted for an ink-printing process for forming a multi-element metal chalcogenide thin film, comprising: distributing the nanoscale multi-element metal chalcogenide powder into an ink.    DESCRIPTION OF DRAWING(S) - The figure shows a flow chart of the method for preparing a multi-element metal chalcogenide.    Preparing at least one container (11)    Loading pure metal element powders, and/or alloy powders, and a chalcogen (12)    Conducting synthesis process (13)    Obtaining multi-element metal chalcogenide. (14)