Following chemical charge trapping in pentacene thin films by selective impurity doping and wavelengtha resolved electric force microscopy Article

Smieska, LM, Pozdin, VA, Luria, JL et al. (2012). Following chemical charge trapping in pentacene thin films by selective impurity doping and wavelengtha resolved electric force microscopy . ADVANCED FUNCTIONAL MATERIALS, 22(24), 5096-5106. 10.1002/adfm.201200595

cited authors

  • Smieska, LM; Pozdin, VA; Luria, JL; Hennig, RG; Hines, MA; Lewis, CA; Marohn, JA

abstract

  • Charge trapping is one of several factors that limit the performance of organic electronic materials, yet even in pentacene, a prototypical smalla molecule semiconductor, the precise chemical nature of charge trapping remains poorly understood. Here the effects of three chemical trapa precursor candidates are examined by layering thina film pentacene transistors with different pentacene defect species. The resulting charge trapping is studied in each device via scanninga probe electric force microscopy coupled with variablea wavelength sample illumination. Firstly, it is found that layering with pentacena 6(13H)-one (PHO) readily produces uniform charge trapping everywhere in the transistor channel, as expected for an active blanketa deposited trapa precursor. However, layering with 6,13-dihydropentacene (DHP) produces fewer, morea isolated traps, closely resembling the surface potential distribution in pristine pentacene thin films. Secondly, the rates of trap-clearing versus illuminating wavelength (trap-clearing spectra) are measured, revealing enhanced trapa clearing rates at wavelengths assigned to the absorption of either pentacene or the charged trap species. The trapa clearing spectrum for the PHO-layered sample closely resembles the spectrum obtained from pentacene aged in a working transistor, while the trapa clearing spectrum for the DHP- layered sample resembles the spectrum observed in pristine pentacene. We conclude that PHO- competently creates traps in pentacene that match the expected trapa clearing spectrum for degraded pentacene, while DHP does not, and that the chemical trap species in aged pentacene is very likely PHO+. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

publication date

  • December 19, 2012

published in

Digital Object Identifier (DOI)

start page

  • 5096

end page

  • 5106

volume

  • 22

issue

  • 24