Study On Photoelectric Properties And Magnetic Field Effect Of Organic Semiconductor Devices

Since C.W.Tang developed the first OLED in 1987, organic semiconductors have attracted a lot of interest in the past years due to their scientific significance and wide application. Organic light-emitting diodes (OLEDs) have become a promising candidate for the next-generation flat panel displays, and the organic solar cells are also challenging the commercial inorganic solar cells due to the intriguing combination of low weight and cost. Moreover, organic semiconductors have abundant and special properties in Electronics, Optics and Spintronics. Recently, magnetic field effects (MFE) were found in non-magnetic OSC-based devices, which have attracted ample experimental and theoretical studies to reveal the underlying mechanism.In addition to comparison with the transverse photovoltaic effect used in the solar cells, lateral photovoltaic effect (LPE) also has a wide range of applications, especially position-sensitive detectors (PSDs).In this thesis, we mainly focused on the electroluminescence and the lateral photovoltaic effect (LPE) in OSC-based devices, and we also investigated the magnetic field effects in the above devices. The contents of this thesis are as follow:(1) Electroluminescence and magnetic field effects in OLEDsThe OLEDs with the structure ofITO/TPD/Alq3/LiF/Al were fabricated.The room temperature electroluminescence (EL) of the devices was studied, and the ozone UV treatment was carried out to improve the performance. Magneto-electroluminescence(MEL) and magneto-conductance (MC) have been investigated, the MC reaches 1.6% and the MEL reaches 7%, respectively. The MEL(B) and MC(B) responses show a non-Lorentzian shape. Furthermore, the voltage dependence of MFE was also investigated. The possible mechanism was discussed.(2) Lateral photovoltaic effects in Si/SiO2/Alx(Alq3)1-x structuresA series of Alx-(Alq3)1-x granular films was deposited on n-type Si(111) substrate using co-evaporation technique. TEM images show the typical microstructural characteristic of granular films.Large lateral photovoltaic effects have been observed.The dependence of temperature on LPE was investigated.With the decrease of temperature, the LPV for the upper layer increase accordingly from 300K to 11 OK first, then keep stable and decrease finally, however, the LPV forthe substrate side keep increasing with the decrease of temperature. Furthermore, the dependence of Al composition on LPE was investigated, LPV is very small for the samples with high Al composition, with the decrease of Al fraction, LPV increases rapidly, reaching an optimal value. However, with the further decrease of Al fraction, the LPV decreases accordingly. Finally, the magnetic field effectson LPE were also measured, no obvious MFE was observed. The mechanism of LPE in the devices was discussed, and was ascribed to the traditional LPE and Dember Effect.