Luminescence Mechanism of Near-Infrared Quantum Dots

Near-infrared quantum dots have unique optical properties, such as high fluorescence quantum yield, long fluorescent life, tunable fluorescence emission wavelength, half peak width and large stokes shift, resisting light bleaching etc. The advantage of "near infrared biological window" gives them great potential application value in biological fluorescent tags, solar cells, quantization calculation, photocatalysis, chemical analysis, food detection, vivo imaging and other fields. At present, the luminescence mechanism research of near-infrared quantum dots is still not comprehensive enough. In this paper, the luminescent principle of three different types of near-infrared quantum dots is summarized, including core/shell structure quantum dots (CdTe/CdSe, CdSe/CdTe/ZnSe, etc), ternary quantum dots (Cu-In-Se, CuInS2, etc) and doped quantum dots (Cu : InP, etc). The luminescence mechanism of Type II core/shell structure is most likely to attribute to the interband recombination luminescence, the ternary structure of quantum dots light emitting mechanism is considered to be due to the intrinsic structure defects, and the luminescence mechanism of doped quantum dots is deemed to result from the impurity defects. The existing problems of near-infrared luminescent principle of quantum dots are also discussed and their development tendency is explored t in this review. A systematic study of luminescence mechanism of near-infrared quantum dots will not only help to understand the luminescent properties of near infrared quantum dots, but also contribute to improve the synthesis methods of quantum dots with similarly high quality.