Study On Flexible Plastic Substrate OLED Array Technology And Organic Photovoltaic Devices

In the field of flat panel displays and renewable energy, flexible optoelectronic devices with their remarkable features drew lots of attention, and as the reciprocal of two photoelectric conversion process devices, mainly in flexible organic light-emitting devices （FOLED） and flexible organic thin-film photovoltaic devices （FOPVD） were focused on. Flexible OLED is an emerging device type in the field of display technologies, known as the“Dream Displays”,“Third-generation Display Technologies”.Alsoe, FOPVD as the representative of new energy devices, because of its advanced preparation technologies, superior performance, low cost and widely use , is drawing a large volume of interest.Currently, however, the improvement of efficiency, the insufficient of stability, the complex preparation of the array process, high cost, greatly affect the industrialization process of flexible organic optoelectronic devices. In response to these problems as well as aiming at the performance improvement of flexible paasive matrix OLED （PMOLED）, array technologies and efficiency of FOPVD, a series of basic and applied basic research work was carried out, which includes:1. By introducing buffer layer between flexible plastic substrate PEN and conductive ITO film, the water and oxygen resisitance and smoothness of flexible substrate were improved, thereby the adhesion between substrate the conductive film was enhanced. Using low temperature DC magnetron sputtering method, sputtering transparent conductive ITO film on a buffer layer, which has been prepared on PEN plastic substrate, was fabricated as the anode of FOLED. With a substrate temperature of 70 oC, a sputtering power of 200 W, a distance of target base of 40 cm, a sputtering pressure of 1 mTorr, a water pressure of 2×10^-5 Torr, a transparent ITO substrate with a sheet resistance of 29.2 /sq and a transmittance of 85.1 % was obtained.2. Research on the architecture, the functional layer material, exciton luminance and the doping mechanism of host-guest of flexible OLED devices was performed. Three kinds of samples of monochrome flexible passive matrix OLED （PMOLED） of red, green, blue color were studied. As for green FOLED, a maximum brightness is 16900 cd/m², and a maximum power efficiency can be 7.59 lm/W at 3.3 V were obtained, when the doping concentration phosphorescent material changes from 0 % to 4 %. This indicated that the brightness increased by 45.7 %, luminous efficiency power efficiency were improved by 50.2 % and 109.6 %, respectively. In the case of red FOLED, a maximum brightness of 8400 cd/m², amaximum power efficiency of 3.02 lm /W at 3.9 V, and amaximum luminous efficiency of 3.75 cd/A was obtained. The FOLED color coordinates shift from orange-red to red. When the doping concentration is 10 %, the Commission Internationale De L E’clariage （CIE） coordinates are （0.66, 0.33）, and pure red light was achieved. As for blue FOLED, a maximum brightness of 7500 cd/m², a maximum power efficiency can be 1.87 lm/W at 3.5 V, and a maximum luminous efficiency of 2.09 cd/A were obtained. When the doping concentration changes from very low to 6 %, the brightness increased by 23.2 % luminous efficiency and power efficiencwere improved by 60.7 % and 70.1 %, respectively.3. After the array technology of flexible 4-inch trichromatic PMOLED was studied, the colorization process of flexible PM-OLED was discussed. Especially, the array design scheme of FOLED display screen and preparation technologies were proposed, which covers device design and laboratory preparation, technical parameters and testing. When the flexible substrate cleaning process, pre-processing technology, photomask design, mechanical mask design, NiCr layer design, ITO layer designs, insulation graphic design, column design, the fabrication of cathode isolation, the vacuum deposition technologies of functional organic materials layer, the deposition technologies of the cathode metal, thin-film encapsulation and other related processes were described, a 4-inch trichromatic flexible PMOLED display was completed including design, programs and sample preparation process, and device parameter evaluation and testing system.4. Based on a polymer material of P3HT, the performance of FOPVDs was investigated. On one hand, the metal oxide MoO3 to a bilayer heterojunction （HJ） device was applied. On the other hand, a buffer layer into body heterojunction devices with structure of ITO/PEDOT: PSS/P3HT: PCBM/Bphen/Ag was introduced. The result showed that a conversion efficiency of 3.30 %, which increased by two orders of magnitude compared to the devices without buffer layer, was obtained. To solve the problem of the low open voltage of single-heterojunction FOPVD, Firstly, the heterojunction device with a middle layer heterojunction was design. Then, an electron donor material SubPc with a high open circuit voltage to improve the open-circuit voltage of the flexible photovoltaic devices was used, whose structure is ITO/SubPc （20 nm）/C60 （40 nm）/BPhen （10 nm）/Ag （130 nm）. A maximum open circuit voltage of 0.87 V for FOPVD was achieved.5. A stack method of mixed thin film to apply thin-film encapsulation to flexible devices was used, and the accelerated life of the FOLED was tested. When the initial luminance was 10000 cd/m², and the applied voltage is 9 V. The lifetime of the tested of five kinds of thin-film encapsulation devices were: 897, 1495, 2093, 2830, and 2890 hrs. Compared the effect of package of the single-layer organic thin film （Monomer）1 with the single-layer inorganic film （Al₂O₃）₁, the half-lifetime of flexible devices increased by 66.7 %. Compared the package of （Monomer+Al₂O₃）₁ with （Monomer）1, life improved by 39.8 %. Compared the package of （Monomer+Al₂O₃）₂ with （Monomer+Al₂O₃）₁, it improve by 35.1 %. Compared the effect of package of （Monomer+Al₂O₃）₃ with （Monomer+Al₂O₃）₂, life time is almost the same, only increased by 2.1 %.In summary, in this thesis the effect of the selection of flexible substrate, the introduction of buffer layer, optimization of optical performance parameters of R, G, B trichromatic light-emitting flexible components, which is based on flexible plastic substrate, array technologies of flexible 4 inches PM-OLED devices, and the preparation of samples, were focus on. Meanwhile, the exploration of of FOPVDs and the properties of thin-film encapsulation technologies, paved a solid way for the development and application of efficient flexible optoelectronic devices.