Study On The Optical Coupling Of Organic Optoelectronic Devices Based On Micro/Nano Structure

In recent years,organic optoelectronic devices?Organic Light-Emitting Diodes,OLEDs;Organic Photo Voltaics,OPVs?have gained much research interests and potential application prospects because of their better performances compared to their conventional inorganic counterparts,which characterize as low cost,solution processible,light in weight,portable,and flexible.Despite that organic optoelectronic devices have been commercially tested in recent years,there still exist some problems concerning large-scale producing,which need to be solved further.Presently,the luminous efficiencies of OLEDs and OPVs are still lower than inorganic components because of higher energy loss during the transformation from light to electricity.Based on the fundamental principles of organic components,the process of light emitting,the mechanism of light losses,and the simulation of light emitting,this paper concerns the fundamental research and the applied fundamental research related to organic optoelectronic devices,which are inspired from the practical problems mentioned above.Firstly,the micro-cavities of the OLEDs structured by DBRs?Distributed Bragg Reflector?with a variety of different reflectivities were produced,and their influences on the performances of OLEDs were studied.It is found that the luminescence spectrum of the components containing higher-reflectivity DBRs are more narrow,and the luminescent intensity and brightness of those components are more enhanced when they are compared with reference components.Next,the various parameters of the micro-cavities of the OLEDs structured by DBRs with a variety of different EML and different reflectivities were calculated using Matlab.Based on the calculation results,the micro-cavities of the OLEDs structured by a variety of different light emitting layers are simulated,and it is found that the peak value of the parameter of forward EL is significantly increased when compared to the micro-cavities of the OLEDs that are not structured by DBRs.This findings further validate that the OLEDs structured by DBRs have promising performances,and also has guiding significance on the research of DBRs and the structures of the micro-cavities of the OLEDs.Secondly,the performances of top-illuminated flexible OPVs that takes Silver-Nanoparticles?Ag NPs?-modified Graphite?SNG?as bottom electrodes were studied.More specifically,the optical physics and the electricity characteristics of SNG and the influence of its thickness on the performances of OPVs were systematically analyzed.It is eventually found that,top-illuminated flexible OPVs can acquire high transformation efficiencies of 2.11%if taking Silver-Nanoparticles-modified Graphite?SNG?as bottom electrodes and the blend of poly?3-hexylthiophene-2,5-diyl?:[6,6]-phenyl-C61-butyric acid methyl ester(P3HT:PC₆₁BM)as active layer.It is believed that the light-enhanced effect caused by metallic silver particles contributes to the improvement of the performances of top-illuminated flexible OPVs,hence the mechanism of that light-enhanced effect is eventually discussed.Finally,a multi-dimensional composite electrode was constructed using zero-dimensional Ag NPs,one-dimensional silver nanowires?Ag NWs?and two-dimensional graphene material,and then was applied to flexible OPVs.After the optical physics and the electricity characteristics of that composite electrode was analyzed,it was found that the existence of Ag NPs and the existence of the heterojunctions constructed by Ag NPs and Ag NWs can significantly improved the light scattering and absorption efficiencies of active layers,which complies with the results given by finite-difference time-domain simulation method.The experimental results show that the OPV with this kind of composite electrode can acquire high power-conversion efficiencies of 7.01%if taking poly[4,8-bis?5-?2-ethylhexyl?thiophen-2-yl?benzo[1,2-b:4,5-b?]dith-iophene-co-3-fluorothieno[3,4-b]thiophene-2-carboxylate]:[6,6]-phenyl-C7l-but-yric acid methyl ester(PTB7-Th:PC₇₁BM)as an active layer.