Femtosecond transient absorption microscopy of singlet exciton motion in side-chain engineered perylene-diimide thin films
We present a statistical analysis of femtosecond transient absorption microscopy applied to four different organic semiconductor thin films based on perylene-diimide (PDI). We achieve a temporal resolution of 12 fs with simultaneous sub-10 nm spatial precision, which enables us to directly probe the...
| Main Authors: | , , , , , , , , , |
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| Format: | Journal article |
| Language: | English |
| Published: |
American Chemical Society
2020
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| Summary: | We present a statistical analysis of femtosecond transient absorption microscopy applied to four different organic semiconductor thin films based on perylene-diimide (PDI). We achieve a temporal resolution of 12 fs with simultaneous sub-10 nm spatial precision, which enables us to directly probe the underlying exciton transport characteristics within 3 ps after photoexcitation free of model assumptions. Our study reveals sub-picosecond coherent exciton transport (12 – 45 cm2 s-1) followed by a diffusive phase of exciton transport (3 – 17 cm2 s-1). A comparison between the different films suggests that the exciton transport in the studied materials is intricately linked to their nanoscale morphology, with PDI films that form crystalline films with large domain sizes exhibiting the largest diffusion coefficients and transport lengths. Our study demonstrates the advantages of directly studying ultrafast transport properties at the nanometer length scale and highlights the need to examine nanoscale morphology when investigating exciton transport in organic as well as inorganic semiconductors. |
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