| dc.description.abstract | Hybrid organic-inorganic lead halide perovskites represent a class of novel solar cell materials that have recently gained interest due to their excellent optoelectronic properties. However, their poor stability and fast degradation hinder commercialization. This work investigates one instability mechanism, light-induced phase segregation, by analyzing hyperspectral photoluminescence (HSPL) images of mixed-halide perovskite solar cells.
The present study aims to use HSPL imaging and accompanying data analysis techniques to map light-induced phase segregation in mixed-halide perovskite solar cells. To achieve this, planar regular (n-i-p) perovskite solar cells were fabricated in REALTEK’s laboratories. HSPL images of these cells were then analyzed using data analysis pipelines comprising some preprocessing steps in addition to principal component analysis (PCA) and multivariate curve resolution (MCR). Supplementary X-ray fluorescence (XRF) images of the samples were also taken in an attempt to assess whether the HSPL images can be used for mapping phase segregation-caused regions of higher and lower concentrations of the perovskite’s halide species (iodide and bromide).
The samples’ photoluminescence (PL) spectra comprise several peaks and shoulders that may originate from phases of different halide stoichiometries. However, it can not be concluded that the observed PL signals are caused by phase segregation since the XRF images from the present XRF setup could not be used for validation. Also, the literature suggests that similar spectral features may be caused by other mechanisms, like re-absorption effects. A thorough analysis of the origins of the various PL signals must be conducted, and a suitable characterization method for validation of the HSPL analysis must be in place before the method can be developed further. Since the literature suggests that the iodide-rich domains are small compared to the resolutions of the present XRF and HSPL setups, increasing the resolution may be necessary to facilitate the localization of such domains. | |
