The Synthesis Of Near-infrared Quantum Dots And Their Applications In Luminescent Nanocrystal-molecule Hybrids

The use of solar energy has received extensive attention due to the increasing demand for clean energy.The investigation of NIR materials has been very attractive recently.Among the investigated NIR materials,NIR quantum dots（QDs）are widely used in energy and biology fields due to their superior absorption of NIR light.Most recently,researchers have realized the photon up-conversion from NIR to visible in QD-organic molecular hybrid.Understanding the properties of NIR QDs and constructing NIR QD-molecular hybrids are significant for photovoltaics.In this thesis,we report a synthesis method of environmentally friendly NIR Zn:Cu In Se₂（Cu In S₂）QDs.By construction of Zn:Cu In Se₂（Cu In S₂）QDs-organic molecular complex,we realized the fluorescence resonance energy transfer（FRET）and thermally activated delayed photoluminescence（TADPL）,respectively.In addition,we revealed the mechanisms of the energy transfer between QD and organic molecule using time-resolved spectroscopy technique.The main innovations of this thesis are as follows:（1）We prepared CuInS₂/ZnS-SQ hybrid and confirmed that the FRET process is the main quenching path of photoluminescence for QDs.The energy transfer efficiency（η）is proportion to the ratio of SQ molecules on Cu In S₂/Zn S QDs.Theηis up to 52%.（2）We report bright,near-infrared TADPL in lead-free CuInSe₂ QDs functionalized with carboxylated tetracene（TCA）ligands,which results from efficient triplet energy transfer from photoexcited QD to TCAs,followed with thermally activated reverse energy transfer from TCA triplets back to QD.This strategy prolonged the QD exciton lifetime from100 ns to 60μs at room temperature.