Spatially Mapping Charge Carrier Density and Defects in Organic Electronics Using Modulation-Amplified Reflectance Spectroscopy

Charge-modulated optical spectroscopy is used to achieve dynamic two-dimensional mapping of the charge-carrier distribution in poly(3-hexylthiophene) thin-film transistors. The resulting in-channel distributions evolve from uniformly symmetric to asymmetrically saturated as the devices are increasingly biased. Furthermore, physical, chemical, and electrical defects are spatially resolved in cases where their presence is not obvious from the device performance.