Spatial and temporal imaging of long-range charge transport in perovskite thin films by ultrafast microscopy.

ABSTRACT: Charge carrier diffusion coefficient and length are important physical parameters for semiconducting materials. Long-range carrier diffusion in perovskite thin films has led to remarkable solar cell efficiencies; however, spatial and temporal mechanisms of charge transport remain unclear. Here we present a direct measurement of carrier transport in space and in time by mapping carrier density with simultaneous ultrafast time resolution and ?50-nm spatial precision in perovskite thin films using transient absorption microscopy. These results directly visualize long-range carrier transport of ?220?nm in 2?ns for solution-processed polycrystalline CH3NH3PbI3 thin films. Variations of the carrier diffusion coefficient at the ?m length scale have been observed with values ranging between 0.05 and 0.08?cm(2)?s(-1). The spatially and temporally resolved measurements reported here underscore the importance of the local morphology and establish an important first step towards discerning the underlying transport properties of perovskite materials.

SUBMITTER: Guo Z 

PROVIDER: S-EPMC4557372 | biostudies-literature | 2015 Jun

REPOSITORIES: biostudies-literature