| DATE: |
2012-05-10 16:00 - 18:00 |
| PLACE: |
#1 meeting room, 2nd floor, 4 go kan Tokai 1go kan #324 |
| TITLE: |
IMSS seminar (12-11):Understanding Interfacial Structure and Diffusion in Multilayer Optoelectronic Devices |
| CONTACT: |
Hironori Nakao4868 |
| SPEAKER: |
Prof. Ian Gentle (the University of Queensland) |
| LANGUAGE: |
English |
| ABSTRACT: |
Since the discovery that small fluorescent compounds and conjugated
polymers could be used as the active material in organic light emitting
diodes (OLEDs) about twenty years ago, intensive research has seen them
move from relatively short-lived and inefficient devices to components
of commercially available appliances. This research has prompted the
development of other organic devices such as organic photovoltaic
devices (OPVs), field-effect transistors (OFETs) and sensors. A
fundamental feature of these devices is that they rely on electron
transfer between layers of organic materials, which imposes certain
requirements on the materials and the way they interact.
Morphologies of model devices based on the architectures of OLEDs, bulk
heterojunction OPVs and fluorescent sensors for explosives have been
studied using a purpose-built cell on the Platypus time-of-flight
neutron reflectometer at Australia”Ēs OPAL reactor and the ISIS Facility
in the UK. Deuterated materials synthesised at the National Deuteration
Facility were used to enhance contrast between the organic layers. Three
device structures have been examined: (i) studies of OLED architectures
revealed that rapid interdiffusion occurs between the emissive layer and
electron transport layer when heated above a critical temperature [1];
(ii) studies of organic photovoltaic solar cells fabricated by
sequential deposition revealed interdiffusion between donor (P3HT) and
acceptor (PCBM) layers [2] and (iii) studies of sensors revealed that
the analyte diffuses reversibly throughout the active layer with
accompanying swelling that depends on the structure of the sensing
material [3, 4]. Our work has shown that diffusion occurs between layers
at relatively low temperatures, having a great effect on performance and
durability. The results have important implications for the long-term
stability of devices based on organic layers. |
|
