The Abnormal Properties Of The Electronic And Optical In Multi-crystalline Alq₃

8-hydroxyquinoline aluminum (Alq3) is an excellent semiconductor fluorescentlight-emitting material. Its physical and chemical properties have been studied extensively,and the research working on this aspect also has made a lot of achievements, such as thenegative resistance effect of organic semiconductor materials, bistable phenomenon,etc.Research in the crystalline Alq3started later, and predecessors obtained four differentcrystal structures via measuring Alq3at different crystallization temperatures.Based on Alq3as an emitting layer in organic diode which occur the dark spotphenomenon as a starting point, through the characterization, testing, analysis anddiscussion of the relevant experiments, we discussed the reasons for the formation of thenegative resistance effect, and summarized the differences of electro-optic in crystallineAlq3vs amorphous Alq3. In this paper, it is divided into three sections:1. The thin film of amorphous Alq3was prepared, and then its morphologieswere characterized by scanning electron microscopy under differentconditions (moisture content, different temperatures, acetone). In order to further determinethe crystalline structure of films, the X-ray diffraction measurement was used to get theresults in conformity with the measurement which the predecessors have done before.2. The polycrystalline thin film Alq3as the organic light emitting layer, was used tofabricate an organic diode(ITO/polycrystalline Alq3/Mg:Ag/Ag) and OLED with theamorphous (ITO/multicrystalline Alq3/Mg:Ag/Ag) Alq3to make the comparison. As a result,polycrystalline Alq3appeared negative resistance effect, and the reasons were explained.Sudsequently, the oscillation circuit was tested and the possibility applications was alsodiscussed for electronics in the future.3. The Alq3was fabricated as polycrystalline films in nanometer scale, and the fieldeffect transistor devices(Silicon/polyimide/polycrystalline Alq3/Au) were prepared. Thecurrent versus voltage curve of the device indicated that the applied gate voltage canmodulate the current(IDS). At ambient enviorment, the current vs voltage curveappeared obvious fluctuation, and the phenomenon was then explained. Crystalline Alq3witha good conductivity lies in its crystal structure. When Alq3turn to crystalline fromamorphous phase, the polar phase polycrystalline nanoparticles is the reason that Alq3has agood conductivity.