Analyzing novel fabrication and doping methods of organic photovoltaic devices through a lumped circuit model
Date
2015
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
University of Delaware
Abstract
The field of organic photovoltaics (OPV) has progressed rapidly. With new materials and methods being briskly developed, the characterization of OPV also needs to be updated. A simple, quantitative analysis that can be shared between labs would help the field achieve uniformity and increase the pace of research. Current-voltage (JV) measurements yield valuable insight into the internal physics of OPV devices. A simple lumped circuit model, previously used to analyze various inorganic thin film PV and more recently applied to OPV, has been used to quantify the electrical behavior of a device. To investigate how the lumped circuit model parameters vary with device treatment, we carried out an annealing study of P3HT:PCBM blend OPV devices. In addition to this study, we also studied the effect of various inorganic materials, such as plasmonic nanoparticles or novel inorganic electrodes on the parameters of the model. We characterized and quantified the effect of these changes (novel materials, thermal annealing, plasmonic nanoparticles, and inorganic electrodes) by studying how the model parameters changed. While studying the resistances in unannealed and annealed devices, a barrier was found around the flat band voltage. This barrier disappeared upon annealing, indicating that it was due to material characteristics related to the crystallinity or the phase separation. In addition to the JV investigations, we investigated where the current in an OPV device originates. Using high resolution microscopy images, we were able to image the workings of a device to greater understand how light is absorbed and where electrons originate. All data was used to better characterize effects of materials on OPV devices and create a framework for future studies to be benchmarked against.