Mapping the space charge carrier dynamics in plasmon-based perovskite solar cells
Energy conversion by the surface plasmon effect is considered a promising alternative to an effective transformation of solar energy in photovoltaic devices through the generation of hot electrons in plasmonic nanostructures. Here, we report the direct visualization of the space charge potential profile across the cross-section of perovskite solar cells before and after plasmonic treatment and the nanoscale photoresponses of perovskite thin films to gain key insights into the fundamental mechanism of the charge carrier dynamics inside the cells during operation. Understanding the charge transport dynamics inside the solar cells is important for identifying the basic processes of the photovoltaic mechanism. Plasmon resonances in metal nanostructures and the accelerated charge transfer improved the overall performances of the solar cells. The recorded photocurrent images reveal an enhanced photo-response at the nanoscale for the plasmonic solar cells due to hot electron generation in Au nanoparticles. In addition, the potential-profiling results also indicate enhanced charge separation in the plasmon-based solar cells, which is associated with the better performances of the devices. The results represent a new feature for plasmonic nanostructures in photovoltaics, which could lead to the tuning of the carrier transfer dynamics inside the cells.