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Characterization of the Local Order of Organic Thin Film Material by Combined Atomic Force Microscopy and Optical Microscopy


EMSL Project ID
25411

Abstract

This project will develop, demonstrate and publish a new method to study the local order of organic thin film materials. The nanometer scale local order and disorder of organic thin film materials are critical properties of the material for light emitting devices, photovoltaic devices and thin film transistors. However, the nanometer size local order cannot be imaged by a conventional optical microscope at length scales below the diffraction limit (about 300 nm). The scanning tunneling microscope or atomic force microscope can make very high resolution images of the surface of a thin film, but it is not possible to relate what is seen to the molecular structure at the nanoscale (i.e. whether roughness is due to crystallites, aggregation or the underlying substrate). In this project, we will design and build a combined microscope based on a conductive atomic force microscope and an optical polarization microscope. With this combined microscope, we will be able to study the spectroscopic properties of organic thin films with resolution far beyond the optical diffraction limit. Such images can be used to extract information on the extent of local nanoscale order in the thin film. By characterizing the local order of the organic thin films, we will be able to understand its effects on material properties, such as charge mobility, exciton diffusion and light emission efficiency. This knowledge will guide us to design and tailor the chemical structure of organic molecules to optimize ordering and thereby control the property of light emitting devices and photovoltaics for maximum energy efficiency.

Project Details

Project type
Large-Scale EMSL Research
Start Date
2007-05-29
End Date
2009-03-31
Status
Closed

Team

Principal Investigator

Dehong Hu
Institution
Environmental Molecular Sciences Laboratory

Team Members

Paul Barbara
Institution
University of Texas at Austin

Asanga Padmaperuma
Institution
Pacific Northwest National Laboratory

Amy Qiao
Institution
Pacific Northwest National Laboratory

Paul Burrows
Institution
Pacific Northwest National Laboratory