LI Yuan,ZHAO Su-ling*,XU Zheng,ZHANG Fu-jun,HUANG Jin-zhao,ZHAO De-wei,JIANG Wei-wei,YAN Guang
Institute of Optoelectronics Technology, Beijing Jiaotong University, Key Laboratory of Luminescence and Optical Information(Beijing Jiaotong University), Ministry of Education, Beijing 100044, China
Abstract：Solid state cathode luminescence (SSCL) is a bran-new excitation mode. In the device, the inorganic semiconductor is used for electron acceleration. After acceleration the energy of electrons may be raised up so high that these hot electrons have enough energy to induce luminescence in the visible region by impact excitation. It is a new development and application of the traditional CRT theory in solid organic/inorganic electroluminescence device, and it is a new method to improve the EL efficiency. a new phenomenon of co-existence of different mechanisms of excitations in addition to these kinds of excitations. It is very important that all these effects are additive，amplifying or compensatory and reinforce the luminescence intensity and make the spectrum of luminescence wider. The accelerating layer of SSCL is the important part of improving the performance of SSCL devices, in which electrons can be accelerated to hot electrons with high energy and obtain electron multiplication. It is the key to improving the performance of SSCL devices, enhancing injecting electrons to increase hot electrons. So we prepared the complex accelerating layer with SiO2, ZnS and ZnO, giving attention to acceleration and injecting property. Firstly, we respectively prepared the devices with the polymer MEH-PPV and SiO2, and ZnS, and ZnO, and found that SiO2/ZnS and ZnO/SiO2 are better. And then contrasting them, we found SiO2/ZnS is better. It’s because that ZnS and ZnO are similar in injecting property, but ZnS is evidently better than ZnO in electron multiplication. SiO2 is the primary accelerating layer, and ZnS can lower the voltage barrier by ladder voltage barrier. Finally, we found that this complex accelerating layer, especially in high electric field, can increase the efficiency of SSCL devices by increasing initial electrons and hot electrons.
Key words：Electroluminescence;Complex accelerating layer;Hot electron;Solid state cathode luminescence
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