Fabrication And Study On Abnormal Energy Transfer At Low Temperature Of Mn²⁺ Doped CsPbCl₃ Nanocrystals

CsPbX₃?X=Cl,Br,I?perovskite nanocrystals are widely studied in recent years due to their excellent optical performance,such as high photoluminescence quantum yield,large bandgap tunability,narrow full width at half maximum?FWHM?,and are expected to become the most commercially valuable luminescent materials in the field of optoelectronic devices in the future.However,its own toxic element Pb will cause harm to human body,and is not environmentally friendly.It has been found that Mn²⁺can be successfully incorporated into the crystal lattice of CsPbCl₃ nanocrystals by hot-injection method,partially replacing Pb²⁺.Mn²⁺doped CsPbCl₃ nanocrystals display two emission bands,including the blue excitonic emission and red Mn²⁺emission.The energy transfer from exciton to Mn²⁺was confirmed,and the transfer efficiency will decrease when temperature decreases from room temperature to 77 K.In addition,the photoluminescence quantum efficiency improved significantly after Mn²⁺-doping at room temperature.In this paper,the main work is about the fabrication of Mn²⁺doped CsPbCl₃nanocrystals with different Mn²⁺concentrations by hot-injection method,and to study the factors affecting the energy transfer efficiency from exciton to Mn²⁺and its physical mechanism through a variety of optical measurement and characterization methods.The experiments confirm the existence of energy transfer process from exciton to Mn²⁺first,and temperature-dependent photoluminescence measurements show that the exciton-Mn²⁺energy transfer efficiency decreases with the decreasing of temperature above 100 K,which is consistent with the results of previous reports.However,an opposite change appeared below 100 K,which means a new mechanism of energy transfer in low temperature.Temperature-dependent measurements of magnetization rate indicates that the new energy transfer mechanism is related to the anti-ferromagnetic interaction between adjacent Mn²⁺at low temperature,which is further proved by photoluminescence measurements under high magnetic field at low temperature.These works will provide important reference for the research and application of CsPbX₃ series perovskite nanocrystals in the future.