Visualizing the Active Paths in Morphologically Defective Organic Thin‐Film Transistors

Abstract

AbstractThe charge‐carrier mobility of organic semiconductors extracted from thin‐film transistors is highly dependent on film morphology. Morphological defects can lead to the underestimation of charge transport properties, which may impede the rational design of novel materials. Herein, a novel analytical method is presented to functionally characterize entire active layers of solution‐processed thin‐film transistors. By correlating imaging and spectroscopy of secondary electrons, nano‐sized morphological defects are discovered and the effective current paths between source and drain electrodes are directly visualized. After image‐processing, the as‐measured mobility values of zone‐cast thin‐films of a tetraazaperopyrene derivative are corrected, obtaining charge–carrier mobilities of up to five times higher than the as‐measured values. The direct visualization of the electric functionality of the organic thin‐films facilitates a unique quantification of the impact of morphological defects and provides a solid benchmark to estimate the potential for further improvement of device performance.