Optoelectronic Nanocomposite Materials for Thin Film Photovoltaics.

摘要

Final results are described for a seed project focusing on the development of inorganic, nanostructured semiconductor based composite thin films intended for use as heterojunction elements or photoactive contact materials for photovoltaic energy conversion devices. The project demonstrated the successful production of quantum size, semiconducting CdTe nanoparticles (light absorption, charge generation material) within a ZnO (transparent conductive oxide, charge transport matrix) using sequential rf sputtering deposition. Unique to this study, the deposition approach allowed the spatial distribution of the semiconductor phase within the host matrix to be controlled, resulting in nanostructure tunable optical absorption and carrier transport behavior of significant impact to the intended application of these materials for spectrally enhanced thin film photovoltaic performance and other optoelectronic technologies. Transmission electron microscopy, x ray diffraction, and vibrational spectroscopy confirmed the identity of the phases participating in the composite as well as the variation in nanostructural characteristics as influenced via deposition control and thermal annealing. The work demonstrated the development of nanocomposite thin films that exhibit tunable, quantum confinement induced modification in spectral absorption based on the manipulation of extended semiconductor phase connectivity. The control of semiconductor phase assembly was also used to optimize photocarrier transport behavior (generated within the CdTe nanophase) as evidenced by spectrally resolved photoconductivity measurement.