USING SELF-ASSEMBLY TO CONTROL PHOTOPHYSICS AND NANOSCALE ARCHITECTURE IN SEMICONDUCTING POLYMER/FULLERENE SOLAR CELLS

摘要

The efficiency of polymer/fullerene bulk-hetero-junction (BHJ) photovoltaics is highly sensitive to the nanoscale structure that evolves during device fabrication. In this work, we aim to develop robust routes to control that architecture using non-covalent intermolecular interactions. Two main methods are discussed here. First, we use sequential processing, where the polymer component of the device is first allowed to crystallize into an ideal nanoscale architecture. The fullerene is then diffused into the structure with retention of nanoscale structure. Devices produced in this way show good efficiency and fundamentally different photophysics than typical BHJ photovoltaics. Second, we synthesize water-soluble semiconducting polymers that can assemble into well-defined structures based on amphiphilic interactions. These polymers can be paired with amphiphilic fullerene derivatives to create water-processable polymer/fullerene assemblies that show a range of exciting phenomena. Novel properties include ultra-fast excited-state electron transfer in solution, the formation of long-lived charge separated species, and solution phase photochromism.