Visualizing the Active Paths in Morphologically Defective Organic Thin‐Film Transistors. (25th August 2021)

• Record Type: Journal Article
• Authors: Zhang, Wen‐Shan; Matthiesen, Maik; Günther, Benjamin; Wensorra, Jakob; Fischer, Daniel; Gade, Lutz H.; Zaumseil, Jana; Schröder, Rasmus R.
• Is Part Of: Advanced Electronic Materials. Volume 7:Number 11(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-08-25
• Subjects: analytic SEM -- charge neutral energy -- charge‐carrier mobility correction -- micromorphology -- organic thin‐film transistors; Materials -- Electric properties -- Periodicals; Materials science -- Periodicals; Magnetic materials -- Periodicals; Electronic apparatus and appliances -- Periodicals; 537
• DOI: 10.1002/aelm.202100400
• Languages: English
• ISSNs: 2199-160X

Abstract

Abstract: The 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. Abstract : The effective current paths in an organic thin‐film transistor are visualized using dynamic surface potential in‐situ generated by ultra‐low voltage scanning electron microscopy. Nano‐ to micro‐scaled morphological defects blocking charge flow between contacts are recognized and thus, the as‐measured charge–carrier mobilities are corrected.