NOVELTY - Increasing nanomaterial quantum yield involves stirring yttrium chloride, oleic acid and 1-octadecylene, heating, cooling, stirring methanol and sodium hydroxide, heating, vacuum degassing, reacting, centrifuging and drying; stirring with lanthanide chloride, oleic acid and 1-octadecene, heating, cooling, stirring methanol, ammonium fluoride and sodium hydroxide, heating, vacuum degassing, reacting, vacuum drying; and mixing with ytterbium chloride, oleic acid and 1-octadecylene, heating, stirring ammonium fluoride, methanol and sodium hydroxide, vacuum degassing, heating, and reacting.    USE - Method for increasing nanomaterial quantum yield (claimed) used for biomarker, analysis and detection, fluorescence imaging and solar cells.    DETAILED DESCRIPTION - Increasing nanomaterial quantum yield comprises taking yttrium chloride, oleic acid and 1-octadecylene, mixing under vacuum, stirring, heating to 100-105 degrees C, keeping temperature for 10-20 minutes, heating to 150-160 degrees C for 30-40 minutes, forming uniform and transparent yellow solution, cooling to room temperature, stirring methanol and sodium hydroxide, heating continuously to 100-105 degrees C, vacuum degassing for 10-20 minutes, warming under inert gas atmosphere to 280-320 degrees C, reacting for 240-300 minutes, cooling, washing, centrifuging and drying under vacuum to get nuclear sodium yttrium fluoride (NaYF4); stirring NaYF4, lanthanide chloride, oleic acid and 1-octadecene under vacuum, heating to 100-105 degrees C, incubating under constant temperature for 10-20 minutes, heating to 150-160 degrees C, keeping temperature for 30-40 minutes, cooling to room temperature, stirring methanol, ammonium fluoride and sodium hydroxide, heating to 100-105 degrees C, keeping under constant temperature for 10-15 minutes, vacuum removing gas for 10-20 minutes, under inert gas environment, heating to 280-320 degrees C, reacting for 120-160 minutes, vacuum drying to obtain core-Shell structure NaYF4:ytterbium (Yb), erbium (Er); and mixing NaYF4:Yb,Er, ytterbium chloride, oleic acid and 1-octadecylene under vacuum, heating to 100-105 degrees C, keeping under constant temperature for 10-20 minutes, heating to 150-160 degrees C, keeping temperature for 30-40 minutes, cooling to room temperature, stirring ammonium fluoride, methanol and sodium hydroxide, continue heating to 100-105 degrees C, keeping under constant temperature for 10-15 minutes, vacuum degassing for 10-20 minutes, under inert gas environment, heating to 280-320 degrees C, and reacting for 120-160 minutes.