Online Seminar Announcement: Wednesday 2 September 2020

Due to the cancellation of many scientific conferences, the AUCAOS committee is pleased to announce an online seminar series. We intend to run seminars on the first Wednesday of every month until normal conferences can resume.

Date: Wednesday 2 September

Time:
1pm (QLD, NSW, ACT, Vic, Tas)
12:30pm (SA, NT)
11am (WA)
3pm (New Zealand)

Click this link to join the meeting: https://jcu.zoom.us/j/94754769654?pwd=ZDdkNXA0R0dkOXFhOTVzREJMT1ZTQT09

Seminar schedule
Each talk is 20 minutes duration followed by approximately 5 minutes for questions and discussion.

Time (QLD time, adjust as needed): Presentation:
1:00 – 1:25pm Nanoscale Capacitor-like Field Buildup Reveals Charge Protection in an Organic Heterojunction

Dr Kyra Schwarz
University of Melbourne

Emerging thin-film solar technologies often comprise nanoscale structural complexity that dramatically impacts the efficiency of light harvesting. Researchers have long considered how to suppress the loss of free carriers by recombination, an effect that is intimately connected to local morphology in the donor–acceptor heterojunctions of organic solar cells. Using femtosecond transient spectroscopies, we report the nanosecond grow-in of a large transient Stark effect, caused by nanoscale electric fields of ~487 kV/cm between photogenerated free carriers in the device active layer. We find that particular morphologies of the active layer lead to an energetic cascade for charge carriers, which in turn leads to the local build-up of electric charge that is resistant to bimolecular recombination and consistent with higher device efficiencies. These observations suggest that with particular nanoscale morphologies the bulk heterojunction can go beyond its established role in charge photogeneration and can act as a network of tiny capacitors, where adjacent free charges are held away from the interface and can be protected from bimolecular recombination.

1:25 – 1:50pm Design and Application of TADF Emitters for Blue and White OLEDs

Dr. Andrew Danos
Durham University

Thermally activated delayed fluorescence has allowed all-organic OLED emitters to reach the high efficiencies previously reserved by organometallic phosphors. Rapid reverse intersystem crossing (rISC) converts non-radiative triplet excitons into emissive singlets in devices, enabled by vibronic coupling of excited states with different multiplicity and orbital character. However this approach is not without drawbacks, and the complexity of the rISC process along with its strong sensitivity to host environment make it challenging to successfully design and implement blue and deep-blue TADF emitters.
Despite these challenges, recent progress in this area has been rapid. In this talk I will outline the general structural features required to design TADF materials, along with the experimental techniques used to screen and characterise their performance. Recent work applying external downconversion layers will also be presented, in which a high performance blue TADF OLED is modified to give white emission without loss of efficiency.

1:50 – 2:00pm Open discussion

 

During the seminar:

  • Please keep your microphone muted unless you are speaking. This is to reduce the background noise and avoid disrupting the presenter.
  • You will be automatically muted when you join the virtual meeting room. To speak, you will need to unmute yourself by using the audio controls in the lower left of the Zoom window.
  • If you have not used Zoom before, then it is recommended that you join 5 minutes before the starting time to ensure that you have your software set up correctly.

Please be aware that the talks will be recorded and posted on the AUCAOS website.

Previous seminars

Previous seminars can be viewed here: https://seminars.aucaos.org.au/

Call for abstracts

Seminars are held on the first Wednesday of each month.

In the spirit of building a community in these challenging times, you are encouraged to give a talk. Do you have a talk that you would have given at a conference that was cancelled? Please consider adapting that talk for this format.

Submit abstract by email to bronson[dot]philippa[at]jcu[dot]edu[dot]au.