Study On Annealing And Modification Layers To SSCL

Solid State Cathodoluminescence(SSCL) is a new kind of luminescence. Different from vacuum cathodeluminescence, SSCL is a process that electrons are accelerated in solids and then stimulated luminescent material to emit light, its wavelength includes exciton luminescence and extending state luminescence. And the short-wave peak based on extending state luminescence is the characteristic spectrum of SSCL.In this dissertation, we made a series of SSCL devices using SiO2 as the electron acceleration layer and MEH-PPV as organic luminescence layer. In the research of ITO/SiO2/MEH-PPV/SiO2/Al, we have found that the long-wave peak is about 630 nm, and as the voltage increases, when the short-wave peak emerges, the long wave will blue shift, and as the short-wave peak intensity increases, the blue shift becomes more obvious. When the frequency is low, this phenomenon is not very obvious, but when the excitation frequency is greater than 1 KHZ, the blue shift becomes very obvious. We attribute the reason to the interaction of 580 nm and 630 nm two light-emitting peaks.In addition, as to the low brightness, shorter resistance voltage life of devices and low exciting voltage of SSCL, we deal with the SSCL devices by annealing and the modification of different layers (such as LiF, ZnO quantum dots and PEDOT:PSS), in order to improve the luminescent properties of the devices.In the annealing experiments, we anneal the whole sandwich structure, single layer MEH-PPV and MEH-PPV in sandwich structure at different temperatures, we found: when the single-layer MEH-PPV in the device ITO/MEH-PPV/SiO2/Al is annealed at 60℃, the device's resistant voltage performance is significantly improved. And this is very conducive to the blue light emission. At the same time, when this annealing is introduced to the sandwich structure (i.e. ITO/SiO2/MEH-PPV/SiO2/Al), we found that when the annealing temperature is 150℃, the luminous intensity of the devices has been significantly improved. And compared to untreated devices, the brightness has been improved by an order of magnitude.In the research of the impact of different modification layers to the device structure ITO/MEH-PPV/SiO2/Al, we have made the devices structure of ITO/MEH-PPV/SiO2/ LiF/Al, ITO/MEH-PPV/SiO2/ZnO quantum dots/Al and ITO/PEDOT:PSS/MEH-PPV/ SiO2/Al. We have found that the exiting voltage of the devices drops from 30 V to about 20 V, and theirⅠ-Ⅴcharacteristic curves show that the injection current of the devices have been improved to some extent. In the experiment of the modification of ZnO quantum dots, perhaps due to the impact of the selected solvent of ZnO, the devices' brightness has not been significantly improved; but for the other two cases of modulation, the devices'brightness has a certain improvement, and compared to the modification of the anode of PEDOT:PSS, the property improves more obviously than the modification of the cathode.