Luminescent Down-shifting Of Doped Quantum Dots And Its Application Research On UV Detection

Owing to their large Stokes shift and long PL lifetime,Mn-doped quantum dots(QDs)have great potential in luminescent down-shifting applications.Herein,a single-channel UV panoramic detection system based on these Mn-doped QDs has been proposed,and the detector's response in UV region has been greatly enhanced due to QDs' long PL lifetime,as well as stable emission matched with CCD's response.Firstly,the QDs@PMMA film was attached on a Si-based CCD camera versus a tapered fiber,and an optical chopper was mounted before the QDs@PMMA film to divide continuous incident light into pulsed light.The long lifetime fluorescence originating from UV signal could be still collected by the CCD camera when the chopper is in the ‘off' state,while the visible light would vanish quickly.Therefore,the single-channel UV panoramic detection could be achieved when the incident light turns on and off reversibly.Secondly,the reasons for the time delays that occur in the detection system are analyzed in depth.When the incident light arrives at the QDs film,both the rising and falling edges of the signal received by the detector exhibit time delay,which is generated from the illumination area cut by the chopper and the QDs PL delay,and is presented in convolution.In this paper,these two models are simplified to be expressed by mathematical equations,and verified by experimental results.Then,a new synthetic method is proposed in order to reduce the component of cadmium,which equipped with good repeatability.In addition,the optimized shell significantly improves the light stability of this material and broadens the application fields of QDs.Finally,a microlens array model based on reflective film is designed to solve the problem of low efficiency of light energy caused by scattering.Besides of increasing the microlens' fill factor,the PL efficiency of QDs@PMMA is also increased by more than 50% by this model.