NOVELTY - Forming monodisperse metal chalcogenide nanocrystals without precursor injection involves combining metal source, chalcogen oxide or chalcogen oxide equivalent, and fluid having reducing agent in one pot at first temperature to form liquid comprising assembly; increasing temperature of assembly to a temperature to initiate nucleation to form nanocrystals; and growing metal chalcogenide nanocrystals without injection of either metal source or chalcogen oxide at a temperature greater than or equal to the temperature for initiating nucleation.    USE - For forming monodisperse metal chalcogenide nanocrystals without precursor injection, where the chalcogenide nanocrystals are CdSe nanocrystals, PbSe nanocrystals or Pd9Se2 nanocrystals (claimed) used as semiconductor nanocrystals in biological sensing (e.g. for biological labeling), LEDs, lasers, solar cells and other optical and electronic devices.    ADVANTAGE - The method allows preparation of well-controlled monodispersed CdSe nanocrystals of various sizes by choice of the metal source and solvent system; and allows preparation of monodisperse metal chalcogenide nanocrystals without precursor injection. The method permits a simple way without precursor injection to make nanocrystals on an industrial scale. The nanocrystals prepared by the method without precursor injection shows high quality to those produced by injection method.    DETAILED DESCRIPTION - Forming monodisperse metal chalcogenide nanocrystals without precursor injection involves combining a metal source, a chalcogen oxide or a chalcogen oxide equivalent, and a fluid comprising a reducing agent in one pot at a first temperature to form a liquid comprising assembly; increasing the temperature of the assembly to a temperature to initiate nucleation to form several metal chalcogenide nanocrystals; and growing the metal chalcogenide nanocrystals without injection of either the metal source or the chalcogen oxide at a temperature equal to or greater than the temperature for initiating nucleation, where crystal growth proceeds without nucleation to form several monodisperse metal chalcogenide nanocrystals.