Nanoplasmonic sensing of CH3NH3PbI3 perovskite formation in mimic of solar cell photoelectrodes

Hybrid metal-halide perovskites have emerged as leading class of semiconductors for photovoltaic devices with remarkable light harvesting efficiencies. The formation of methylammonium lead iodide (CH3NH3PbI3) perovskite into mesoporous titania (TiO2) scaffold by a sequential deposition technique is known to offer better control over the perovskite morphology. The growth reactions at the mesoporous TiO2 film depend on reactants concentration in the host matrix and the reaction activation energy. Here, we are characterizing formation of CH3NH3PbI3 perovskite in mimic solar cell photoelectrodes utilizing the developed NanoPlasmonic Sensing (NPS) approach. Based on dielectric changes at the TiO2 mesoporous film interface, the technique provides time-resolved spectral shifts of the localized surface plasmon resonance that varies widely depending on the different operating temperatures and methylammonium iodide (CH3NH3I) concentrations. Analytical studies included Ellipsometry, Scanning Electron Microscopy, and X-ray diffraction. The results show that perovskite conversion can be obtained at lower CH3NH3I concentrations if reaction activation energy is lowered. A significant finding is that the NPS response at 350 nm mesoporous TiO2 can widely change from red shifts to blue shifts depending on extent of conversion and morphology of perovskite formed at given reaction conditions.