Organic Light Emitting Devices And Organic Thin Film Transistors For Full Organic Active Display

With the rapid development of Internet technologyand update of new media applications, humans have growing demands for high quality display. Thanks to this progress it is possible, today, to integrate sensing, processing and communication functions into a user-friendly wearable system. Consider both large size and portability, flexible active-matrix organic light emitting display(AMOLED) attract most attention among display technologies. Organic light-emititng diodes(OLED) work as display unit that have many advantages such as self-emission, solid-state, wide material sourse and wide operating temperature. To further satisfy the requirements of commercial application, much more effort should be made on the improvements of OLED’s performances. Moreover, the organic thin film transistor(OTFT) worked as driven unit which is also important in realizing flexible active-matrix display. In this article, the solutions to fabricate OLEDs with high efficiency and top-emitting white OLEDs are presented in order to improving the performances of OLEDs for practical use and integrating OLEDs on active matrix. Furthurmore, we also investigate the phthalocyanines-based and pentacene-based OTFTs.The main research achievements involved in this thesis are as follows:1、High efficiency Iridium(III) bis(4-phenylthieno [3,2-c] pyridinato-N,C’) acetylacetonate(PO-01) basedyellow organic light-emitting devices are fabricated by employing multiple emission layers. The efficiency of the device using 4,4’,4’’-tris(N-carbazolyl) triphenylamine(TCTA) as potential barrier layer(PBL) outperforms those devices based on other PBLs and detailed analysis is carried out to reveal themechanisms. A forward-viewing current efficiency(CE) of 65.21 cd/A, which corresponds to a maximumtotal CE of 110.85 cd/A is achieved at 335.8 cd/m2 in the optimized device without any outcouplingenhancement structures. We also summarize the design approach of the PBL:(i) a hole-transport preferable materialto suppress the emission of the HTL(such as NPB reported in this article); and(ii) realize a better energylevel alignment with the EML.2、We demonstrate top-emitting white organic light-emitting diode(TEWOLED) based on copper(Cu) top cathode and copper bottom anode, which is suitable for full-color AMOLED with high resolution. Cu exhibits good thermal conductivity and malleability. In our TEWOLED, we introduce TCTA:Mo Ox HIL combine with TCTA HTL structure in order to lower the energy consumption. The special designed structure will guarantee efficient hole-injection/transportion from function layer to emision layer. In terms of improving electron injection, the structure of Cs2CO3/Al is introducd. Meanwhile, our TEWOLED exhibit reduced roll-off in efficiency. This reduction can be attributed to the following reasons. On the one hand, 26 DCz PPy is a bipolar host, it can broad the exciton recombination zone. On the other hand, from the device energy level diagram, we can find that the eletron transport barrier in Bphen/26 DCzppy interface is only 0.05 e V. Thus, electron can transport into the emitting layer easily. But when electrons arrive at Tc Ta/26 DCz PPy interface the energy barrier increase to 0.2 e V. Thus the electron can be well confined in emitting layer. For the same reason, the hole can also be well confined, leading to a reduced roll-off. We also present a Tc Ta capping layer. The electroluminescence spectra of the dvice utlizing the capping layer exhibt negligible angle dependence and extremely stable spectra over a wide luminance range.3、First,we insert a pentacene buffer layer between Au and phthalocyanine material. When the thickness of buffer layer reached to 5nm, the performance of OTFTs is best. We analyzed the variation of performance caused by the thickness of the buffer layer.Second,we insert a Mo Ox buffer layer between Au and Cu Pc. When the thickness of buffer layer varied from 0 to 10 nm, the performance of OTFTs increased. and when the buffer layer thickness increased, the performance of the OTFTs is almost same as 10 nm. So we can see the result that the hole injection barrier and contact resistance decreased by the Mo Ox buffer layer.4、We doped an excellent hole-transport material NPB into the conductive channel of traditional bottom gate top-contact device. It developed the hole transport ability of OTFTs and decreased the threshold voltage value. And we determined the thickness of the conductive channel of OTFTs by changing the thickness of the doped layer. It helped us to research the contact properties of the insulator surface.