Document Type

Journal Article

Department/Unit

Department of Physics

Title

Probing bulk transport, interfacial disorders, and molecular orientations of amorphous semiconductors in a thin-film transistor configuration

Abstract

Thin film transistors (TFTs) can be used to determine the bulk-like mobilities of amorphous semiconductors. Different amine-based organic hole transporting materials (HTs) used in organic light-emitting diodes have been investigated. In addition, the present study also measures the TFT hole mobilities of two iridium phosphors: Ir(ppy)3 and Ir(piq)3. These materials are grown separately on SiO2 and polystyrene (PS). On SiO2, the TFT mobilities are found to be 1–2 orders smaller than the bulk values obtained by time-of-flight (TOF) technique. On PS gate dielectric layer, the TFT mobilities are in good agreement TOF data. Only 10 nm of organic semiconductor is sufficient for TFTs to achieve TOF mobilities. Using the Gaussian disorder model, it is found that on SiO2 surface, when compared to the bulk values, the energetic disorders (s) of the HTs increase and simultaneously, the high temperature limits (µ∞) of the carrier mobilities decrease. Both s and µ∞ contribute to the reduction of the carrier mobility. The increase in s is related to the presence of randomly oriented polar Si-O bonds. The reduction of µ∞ on SiO2 is related to the orientations of the more planar molecules which tend to lie horizontally on the surface.

Publication Year

2016

Journal Title

Advanced Electronic Materials

Volume number

2

Issue number

3

Publisher

Wiley-Blackwell

First Page (page number)

1500273

Last Page (page number)

1500273

Referreed

1

DOI

10.1002/aelm.201500273

Link to Publisher’s Edition

http://dx.doi.org/10.1002/aelm.201500273

Keywords

charge transport, molecular orientation, organic light emitting diodes, organic thin-film transistors, time of flight

ISSN (electronic)

2199160X

This document is currently not available here.

Share

COinS