Nanoscale functional and structural characterization of thin film photovoltaic materials and devices using scanning probe microscopic techniques
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윤요한 항공대 We are exploring different experimental approaches to characterize the functional properties of thin-film PV devices at the spatial scale of single grain or grain boundaries to correlate these with their structure at nanoscale. Two scanning probe nano-spectroscopy techniques, near-field scanning optical microscopy (NSOM) and photothermal induced resonance (PTIR), are leveraged to probe the nanoscale electrical and optical properties of thin film solar cells to observe the inhomogeneity of the samples with high spatial resolution. The two techniques have complementary strengths and capabilities that are particularly useful in combination. The approach is highly successful and significant providing information on material composition through mapping of the band gap over the polycrystalline material and distribution of deep defects that cause undesired recombination and limit the efficiency. The novelty of the methodology used here will pave way for the future applications to detect fluctuations in the optical and electrical properties of PV materials. |