Understanding Organic Photovoltaic Cells: Electrode, Nanostructure,Reliability, and Performance.

Organic Photovoltaic Cell;Materials Science and Engineering;Engineering;Materials Science and Engineering

Kim, Myung-SuVan Der Ven, Anton ;

University of Michigan

关键词: Organic Photovoltaic Cell;    Materials Science and Engineering;    Engineering;    Materials Science and Engineering;   

Others  :  https://deepblue.lib.umich.edu/bitstream/handle/2027.42/62335/myungsu_1.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

My Ph.D. research has focused on alternative renewable energy using organicsemiconductors. During my study, first, I have established reliable characterizationmethods of organic photovoltaic devices. More specifically, less than 5% variation ofpower conversion efficiency of fabricated organic blend photovoltaic cells (OBPC) wasachieved after optimization. The reproducibility of organic photovoltaic cell performanceis one of the essential issues that must be clarified before beginning serious investigationsof the application of creative and challenging ideas.Second, the relationships between fill factor (FF) and process variables have beendemonstrated with series and shunt resistance, and this provided a chance to understandthe electrical device behavior. In the blend layer, series resistance (Rs) and shuntresistance (Rsh) were varied by controlling the morphology of the blend layer, theregioregularity of the conjugated polymer, and the thickness of the blend layer. At theinterface between the cathode including PEDOT:PSS and the blend layer, cathodeconductivity was controlled by varying the structure of the cathode or adding an additive.Third, we thoroughly examined possible characterization mistakes in OPVC . Onesignificant characterization mistake is observed when the crossbar electrode geometry ofOPVC using PEDOT:PSS was fabricated and characterized with illumination which islarger than the actual device area. The hypothesis to explain this overestimation wasexcess photo-current generated from the cell region outside the overlapped electrode area,where PEDOT:PSS plays as anode and this was clearly supported with investigations.Finally, I incorporated a creative idea, which enhances the exciton dissociationefficiency by increasing the interface area between donor and acceptor to improve thepower conversion efficiency of organic photovoltaic cells. To achieve this, nanoimprintlithography was applied for interface area increase. To clarify the effect of the interfacearea between donor and acceptor, we used two kinds of device structures. One wasITO/thermally deprotectable poly thiophene (TDPTD) /PCBM/Al and the other wasITO/TiO2/P3HT/gold (Au). In both cases, the enhanced device performance dependingon the interface area was observed.