We investigate the role of grain structures in nanoscale
carrier
dynamics of polycrystalline solar cells. By using Kelvin probe force
microscopy (KPFM) and near-field scanning photocurrent microscopy
(NSPM) techniques, we characterize nanoscopic photovoltage and photocurrent
patterns of inorganic CdTe and organic–inorganic hybrid perovskite
solar cells. For CdTe solar cells, we analyze the nanoscale electric
power patterns that are created by correlating nanoscale photovoltage
and photocurrent maps on the same location. Distinct relations between
the sample preparation conditions and the nanoscale photovoltaic properties
of microscopic CdTe grain structures are observed. The same techniques
are applied for characterization of a perovskite solar cell. It is
found that a moderate amount of PbI2near grain boundaries
leads to the enhanced photogenerated carrier collections at grain
boundaries. Finally, the capabilities and the limitations of the nanoscale
techniques are discussed.