Final Report Summary - HYBRIDSOLAR (Morphology and Molecular Packing in Polymer-Nanocrystal Hybrid Solar Cells Revealed with Synchrotron X-ray Characterization and Other Techniques)
The packing and morphology of both the AgBiS2 nanocrystals and the polymer hole transport layer were controlled by varying processing conditions such as the annealing, the solvent, the solution concentration, and the ligand-exchange process, thus completing Objective 1. The morphology and packing of the materials were probed with a variety of techniques including UV-vis spectroscopy, x-ray photoemission spectroscopy (XPS), ultraviolet photoemission spectroscopy (UPS), small-angle X-ray scattering (SAXS), and wide-angle x-ray scattering (WAXS). These measurements were performed onsite at ICFO, in collaborator’s labs, or at either the ALBA synchrotron lightsource or the European Synchrotron Radiation Facility (ESRF). In order to complete Objectives 2 and 3, the measurement results were correlated with solar-cell performance, as indicated measurements of current-voltage (I-V) curves, external quantum efficiency (EQE), transient photovoltage (TPV), transient photocurrent (TPC), and Suns open-circuit voltage (Suns-Voc).
The understanding gained from the activities described above enabled us to improve the design of our solar cells and thereby achieve impressive efficiencies and fulfill Objective 4. Although solar-cell efficiencies were below 1% at the beginning of this project, our efforts have resulted in efficiencies up to 6.3%. To our knowledge, this represents the highest efficiency of any nontoxic nanoparticle solar cells that are solution processed at low temperatures. Our main results have been included in a patent application and a manuscript that is currently under review.