TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Method: The process of preparing copper-indium/gallium-(copper2-x)selenium core-shell structure of nano-crystalline precursor comprises: adopting liquid phase reduction to prepare copper nano-crystalline core; utilizing heterogeneous phase reduction to precipitate a (copper2-x)-selenium shell layer at the outer face of the copper crystalline core and obtaining the wrapped substance of copper-indium/gallium-(copper2-x)-selenium core-shell structure; adopting liquid phase composition to wrap the wrapped substance of copper-indium/gallium-(copper2-x)-selenium core-shell structure with a layer of (copper2-x)-selenium shell layer to obtain nano-crystalline precursor. The copper nano-crystalline core is prepared at -5 to 5 degrees C through reduction reaction between solution of nantokite, reducing agent sodium borohydride or hydrazine in the presence of complexing agent and dispersing agent of water-soluble macromolecule, centrifuging and washing, where: the molar ratio of the nantokite and the reducing agent is 1:1-2; the molar ratio of the nantokite and the complexing agent is 10-15:1; and the molar ratio of nantokite and the complexing agent is 50-100:1. The process of precipitating the indium/gallium layer on the surface of the copper crystalline core comprises adding the copper nano-crystalline core in the solution containing indium salt and gallium salt in the presence of complexing agent and dispersing agent of water-soluble macromolecule at 50-100 degrees C, carrying out reduction by using the reducing agent sodium borohydride solution or hydrazine and obtaining the wrapped substance of copper-indium/gallium through separating and washing and counting by the molar number of indium and gallium, where: the molar ratio between the molar number of indium and gallium and the reducing agent is 1:1-2; molar ratio of the molar number of indium and gallium and the complexing agent is 10-15:1; the molar ratio of the molar number of indium and gallium and the dispersing agent is 50-100:1; the molar ratio of the molar number of indium and gallium and gallium is 1:0.2-0.4; and the molar ratio of the molar number of indium and gallium and copper is 2:1. The process of wrapping the copper-indium/gallium nano-crystalline core with a (copper2-x)-selenium shell layer comprises adding the wrapped substance of copper-indium/gallium in cuprammonium, mixing the wrapped substance of copper-indium/gallium with ammonium hydroxide containing sodium thioglycollate and dissolved selenium powder, stewing, fully precipitating and obtaining copper-indium-(copper2-x)-selenium nano-crystalline precursor with three layers of core shell structure, where the proportion of copper, (indium and gallium) and selenium is 1:1:1-2. The quick selenizing rapid thermal annealing process achieved in a dual temperature selenylation furnace comprises preserving temperature of the selenium powder on condition that the vacuum degree is not greater than 10 Pa and temperature is between 205-350 degrees C, rising temperature of the precursor film to 450-550 degrees C at a speed of 500 degrees C/minute and selenizing for 2-5 minutes.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The complexing agent and the dispersing agent are citric acid, pyrimidine, aminotriacetic acid, ethylenediaminetetraacetic acid, tetraoctyl ammonium bromide, polyvinylpyrrolidone and/or polyethylene glycol.