Solution-processable white-light-emitting germanium nanocrystals

• Visible light emitting nanocrystals of germanium was synthesized by chemical reduction of germanium iodide.
• White light emission was achieved by control over size distribution of germanium nanocrystals.
• Tuning the color of white light was achieved by separation of nanocrystals by emission.

This paper describes an efficient chemical route for the synthesis of visible light emitting nanocrystals of germanium (ncGe). The synthesis started by heating Ge(II) iodide at 300 °C in argon atmosphere. Spectroscopic characterizations confirmed the formation of diamond cubic lattice structures of ncGe. By grafting hydrophobic chains on the ncGe surface, the dispersions in nonpolar solvents of the ncGe became very stable. The as-synthesized ncGe showed the bluish white photoluminescence (PL) feature, but it was found that the PL spectrum is composed of many different emission spectra. Therefore, the color-tuning of white light emission is demonstrated through the witting removal of extra ncGe with unfavorable emission feature by making full use of column chromatographic techniques.

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