Online Seminar Announcement: Wednesday 7 April 2021

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 7 April 2021

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

Please note different times in some states due to the end of daylight savings time.

Click this link to join the meeting: https://jcu.zoom.us/j/86449047647

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 Organic Polariton Lasing with Molecularly Isolated Perylene Diimides

Dr. Girish Lakhwani
Sydney University

In the last decade, strong light matter coupling has become an alternative path to achieve lasing in organic materials via use of polaritons. Polariton lasers do not require population inversion and thus hold the promise of lower laser thresholds. Organic materials are particularly suited for polariton lasing as their large absorption coefficients result in impressive exciton-photon couplings strengths at room temperature. Here I will demonstrate polariton lasing in a molecularly isolated perylene diimide. [1,2] The emission exhibits threshold behaviour, spatial coherence, and the characteristic blue-shifting of polariton systems. We expect perylene dyes will become a useful polariton laser class.

1. Sabatini et al. J Mater Chem C, 7, 2954 (2019)
2. Sabatini et al. Appl. Phys. Lett, 117, 041103 (2020)

1:25 – 1:50pm Optimal quantum dot size for photovoltaics with fusion

Dr. Laszlo Frazer
Monash University

Light fusion increases the efficiency of solar cells by converting photons with lower energy than the bandgap into higher energy photons. The solar cell converts the produced photons to current. We use Monte Carlo simulation to predict that lead sulfide quantum dot sensitizers will enable fusion with a figure of merit on the mA/cm^2 scale, exceeding current records, while enabling silicon cell compatibility. Performance is highly sensitive to quantum dot size, on the order of mA/cm^2/nm.

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.


Online Seminar Announcement: Wednesday 10 March 2021

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 10 March 2021

Time:
1pm in QLD
2pm in NSW, ACT, Vic and Tas
11am in WA
12:30pm in NT
1:30pm in SA
4pm in New Zealand

Click this link to join the meeting: https://jcu.zoom.us/j/81590417076

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 N-Heterocyclic Carbene Platinum(II) Dialkynyl Complexes – A New Class of Highly Tunable and Efficient Emitter Systems

Assoc. Prof. Koushik Venkatesan
Macquarie University

New and efficient light-emitting materials are required for a broad range of potential applications in the fields of sensors, storage, photoelectronic devices, and optical devices. Extensive investigations on transition metal complexes as triplet emitters for application in phosphorescent organic light emitting devices (PhOLEDs) have been carried out. Metal complexes with specific ligand environment allow to tailor the luminescent properties in a precise fashion for a specific application. Achieving high stability, high quantum efficiency and specific chromaticity remains a major challenge in this field. Recently, our group has demonstrated a series of highly emissive platinum(II) complexes bearing N-heterocyclic carbene ligands with promising photophysical properties. Further building on this work, we have developed new series of small molecules and investigated their detailed luminescent properties. Selected molecules that have been fabricated into devices show high potential for applications in light emitting devices.

1:25 – 1:50pm Classification of Coherent Enhancements of Light-Harvesting Processes

Assoc. Prof. Ivan Kassal
The University of Sydney

Several kinds of coherence have recently been shown to affect the performance of light-harvesting systems, in some cases significantly improving their efficiency. Recently, we classified the possible mechanisms of coherent efficiency enhancements [1], based on the types of coherence that can characterize a light-harvesting system and the types of processes these coherences can affect. We show that enhancements are possible only when coherences and dissipative effects are best described in different bases of states. In addition, our classification allows us to predict a previously unreported coherent enhancement mechanism.

I will discuss the implications of this classification for the field of organic photovoltaics. Several coherent mechanisms have been proposed for boosting OPV efficiency, but most of them are impossible. A few manifestations of coherence may matter, including one that we are confident plays a big role in OPV performance [2].

[1] Stefano Tomasi and Ivan Kassal, J. Phys. Chem. Lett. 2020, 11, 2348–2355.

[2] Daniel Balzer, Thijs J.A.M. Smolders, David Blyth, Samantha N. Hood, and Ivan Kassal, Chem. Sci. doi:10.1039/D0SC04116E (2021).

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.


Online Seminar Announcement: Wednesday 3 February 2021

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 3 February 2021

Time:
1pm in QLD
2pm in NSW, ACT, Vic and Tas
11am in WA
12:30pm in NT
1:30pm in SA
4pm in New Zealand

Click this link to join the meeting: https://jcu.zoom.us/j/89897826579

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 A flexible organic solar cell based on doped graphene/PET substrate

Dr. Hellen Jin
The University of Queensland

Graphene has shown tremendous potential as a transparent conductive electrode (TCE) for flexible organic solar cells (OSCs). However, the trade-off between electrical conductance and transparency as well as surface roughness of the graphene TCE with increasing layer number limits power conversion efficiency (PCE) enhancement and its use for large-area OSCs. Here, we use a 300 nm-thick poly[(2,5-bis(2-hexyldecyloxy)phenylene)-alt-(5,6-difluoro-4,7-di(thiophen-2-yl)benzo[c]-[1,2,5]thiadiazole)]:[6,6]-phenyl-C71-butyric acid methyl ester as the photoactive layer and a benzimidazole (BI)-doped graphene as the transparent anode to demonstrate efficient OSCs with good flexibility. It is found that 3 layer (L) graphene had the best balance between sheet resistance, optical transmittance and surface roughness for optimized cell design. A 0.2 cm2 cell with a 3L BI-doped graphene anode achieves a PCE of 6.85%, which is one of the highest PCE values reported so far for flexible graphene anode-based OSCs. The flexible cells are robust, showing only a small performance degradation during up to 250 flexing cycles. Moreover, the combination of the thick photoactive layer with the optimized 3L BI-doped graphene TCE enabled production of 1.6 cm2 flexible OSCs with a PCE of 1.8%. Our work illustrates the importance of graphene TCE development for flexible OSCs as well as other wearable optoelectronic devices.

1:25 – 1:50pm Carbene-metal-amides as emitting materials in high-efficiency organic light-emitting diodes

Dr. Patrick Conaghan
University of Sydney / University of Cambridge

Emitting materials in organic light-emitting diodes are predominantly phosphorescent iridium complexes or all-organic thermally activated delayed fluorescence materials. We have demonstrated that the carbene-metal-amide molecular structure of coinage-metal complexes can also be used to produce organic light-emitting diodes with efficient electroluminescence from both singlet and triplet excited states.
We have shown that the emission colour can be changed through variation of the electron-donating strength of the donor moiety and the polarity of the host environment and have used both of these effects to produce devices with emission across the visible range. By engineering excited state energies we have fabricated green-emitting devices with a maximum electroluminescence quantum efficiency of 26.9 % and blue-emitting devices (Commission Internationale de l’Éclairage co‐ordinates [0.17, 0.17]) with external quantum efficiency of 20.9 %.
Transient photoluminescence measurements at varying temperatures show that the emission process is thermally activated with short excited-state lifetimes (<1 μs) and along with device data show that the energy of local triplet excited states imposes an energy limit on efficient emission. Carbene-metal-amides do not show a strong concentration-dependent luminescence quenching in the solid state, which has allowed us to fabricate host-free devices with external quantum efficiency of up to 23 % which, to our knowledge, is the highest reported for host-free organic light-emitting diodes.

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.


Online Seminar Announcement: Wednesday 2 December 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 December 2020

Time:
1pm in QLD
2pm in NSW, ACT, Vic and Tas
11am in WA
12:30pm in NT
1:30pm in SA
4pm in New Zealand

Click this link to join the meeting: https://jcu.zoom.us/j/84452910435

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 Non-Toxic Hybrid Inorganic-Organic Chromophores for the Advancement of Luminescent Solar Concentrators

Calum Gordon
Victoria University of Wellington

Luminescent solar concentrators (LSCs) consist of a waveguide medium containing light harvesting chromophores of an inorganic or organic nature. These chromophores absorb incoming light, and radiatively re-emit light, which is propagated to the edges of the LSC by the waveguide. The concentrated light at the edges is then collected by coupled solar cells.
The advantages of LSCs coupled to solar cells relative to stand alone solar cells are that LSCs are cheaper, and can capture indirect sunlight.
A pressing issue with modern LSCs are re-absorption events by the chromophore, which dampens their efficiency. This is due to overlap between the absorbance and emission spectra of the chromophore.
By coupling inorganic and organic components together, Förster resonance energy transfer (FRET) may be achieved between the two components, creating a donor-acceptor system. The donors absorbance spectrum is sufficiently separated from the acceptors emission spectrum, mitigating re-absorption events.

1:25 – 1:50pm Magnetic field effect on UC-TTA

Elham Gholizadeh
The University of New South Wales

Solar light contains many wavelengths, but solar cells cannot absorb all those wavelengths. In fact, those photons which do not have enough energy to be absorb by the band gap will be wasted. One of the strategies that have been used until now in terms of using low energy photons is Triplet-Triplet Annhilation upconversion (UC-TTA). In this process two low energy photons will convert to a higher energy photon.
In terms of improving solar cells efficiency, it is important to make an upconversion system which convert photons below the bandgap to the photons that absorb by the solar cell. Also, since most of the upconversion system does not work in oxygen environment, finding a solution for this problem looks essential.
In my PhD, I could do UC-TTA from below the silicon bandgap in oxygen mediated environment. In this system, opposite other UC-TTA systems, oxygen improves the upconversion efficiency. So, in terms of understanding the mechanism of UC-TTA in our system in the presence of oxygen, magnetic field effect on TTA process was used. We also considered magnetic field effect on two well known UC-TTA system to be able to modify Merrifield equation and the data was fitted by this equation.

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.


Online Seminar Announcement: Wednesday 4 November 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 4 November

Time:
1pm in QLD
2pm in NSW, ACT, Vic and Tas
11am in WA
12:30pm in NT
1:30pm in SA
4pm in New Zealand

Click this link to join the meeting: https://jcu.zoom.us/j/86786170885

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 Partial Delocalisation Enhances the Efficiency of Charge Separation in Organic Photovoltaics

Daniel Balzer
The University of Sydney

In organic photovoltaics, the question of how charges are able to overcome their significant coulombic attraction and separate has attracted heated debate. In particular, the low dielectric constants in organic semiconductors produce coulombic barriers that are an order of magnitude greater than the available thermal energy. One of the proposed answers is delocalisation, including arguments that the increased separation of charges in the CT state reduces the coulombic barrier. However, it turns out that delocalisation stabilises the CT state and increases the coulombic barrier, and therefore any benefit provided by delocalisation must come from non-equilibrium kinetic effects. However, charge separation is a two-body problem involving the correlated motion of an electron and a hole, meaning that the computational difficulty is roughly the square of the single-body mobility calculation, meaning that a fully quantum-mechanical treatment has so far proved intractable in three dimensions. A complete kinetic model would help settle the debate about the main drivers of charge separation, and unite the proposed mechanisms including delocalisation, entropy and energy gradients. Last year, we presented delocalised kinetic Monte Carlo (dKMC), the first three-dimensional model of partially delocalised charge and exciton transport in materials in the intermediate disorder regime. Here, we use dKMC to make the charge separation problem computationally accessible, allowing the first simulation of the full dynamics (and, therefore, efficiency) of charge separation in the presence of disorder, delocalisation, polaron formation and noise. We find that small amounts of delocalisation can produce large enhancements in the efficiency at which charges separate.

1:25 – 1:50pm Spatially Correlated Quantum Properties in Organic Light Emitting Diodes

William Pappas
The University of New South Wales

Electronic spin is a quantum mechanical property that is fundamental to the charge-light conversion processes in optoelectronic devices. The suppression of interactions between spins in organic semiconductors leads to relatively long relaxation times (μs) and results in the formation of weakly coulombically bound electron-hole pairs. The ability to access and modulate the spin polarisation of these pairs enhances the quantum efficiencies of device DC observables (current, luminosity), while also enabling unique functionality in spin-logic devices.
In organic light-emitting diodes, the study of spin-dependent processes giving rise to magnetic field effects have been treated monolithically. We have incorporated optical imaging microscopy into a traditional magneto-electroluminescence (MEL) setup that has allowed us to discern the intra-device variation of the quantum property (hyperfine interaction) which is responsible for these effects. We investigated the correlations between these local hyperfine field strengths in both the spatial and temporal domains. Magnetic resonance measurements are then used explain the origin of variations in the MEL lineshapes.
This work is an important step in characterising the homogeneity of spin-dependent properties in organic materials which critically control the ability to manipulate spins in organic spintronic devices.

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.


Dr Nathaniel Davis awarded Rutherford Discovery Fellowship

AUCAOS member Dr Nathaniel Davis has won a Rutherford Discovery Fellowship. The research is entitled “Pushing the limits on renewable energy technology through hybrid organic/inorganic nanomaterials”.

Follow the link below for further details:

https://www.royalsociety.org.nz/news/latest-10-fellows-announced-in-10th-year-of-rutherford-discovery-fellowship-awards/?fbclid=IwAR3MOgWQo4e4bVkLuP42vNsm4TZ1xrKdGxnA8nROPX7aHjzzVnDoZLBrVkg


ARENA announces funding of project to be led by AUCAOS member Dr David Jones aiming to increase solar cell efficiency.

The project is entitled “New Materials-Singlet Fission Enhanced Silicon Solar Cells” and aims to demonstrate effective use of high energy photons in order to improve solar cell efficiency by using multiple exciton generation (MEG).

This exciting project will include AUCAOS members Dr David Jones of Melbourne University, and Dr Paul Shaw and Professor Paul Burn of The University of Queensland.

For further information please follow the links below:

https://arena.gov.au/projects/new-materials-singlet-fission-enhanced-silicon-solar-cells/

https://arena.gov.au/news/research-boost-for-solar-panel-efficiency-and-cost-reduction/


Online Seminar Announcement: Wednesday 7 October 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 7 October

Time:
1pm in QLD
2pm in NSW, ACT, Vic and Tas
11am in WA
12:30pm in NT
1:30pm in SA
4pm in New Zealand

Click this link to join the meeting: https://jcu.zoom.us/j/85305949649

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 Understanding the interplay between charge transport, luminescence efficiency and morphology in OLEDs using a combined computational & experimental approach

Mile Gao
The University of Queensland

Phosphorescent emissive materials in organic light-emitting diodes (OLEDs) manufactured using evaporation are usually blended with host materials at a concentration of 3–15 wt% to avoid concentration quenching of the luminescence. In this work, experimental measurements of hole mobility and photoluminescence are related to the atomic level morphology of films created using atomistic nonequilibrium molecular dynamics simulations mimicking the evaporation process with similar guest concentrations as that used in operational test devices. It was found that the photophysical and charge transport properties of the film have significantly different guest–guest distance dependence.

1:25 – 1:50pm The effect of gate conductance on hygroscopic insulator organic field effect transistors

Joshua Arthur
Queensland University of Technology

Organic thin film transistors (OTFTs), employing a variety of device architectures, materials, and transduction mechanisms, have shown great promise as effective chemical and biological sensors. One such class of OTFT is the hygroscopic insulator field effect transistor (HIFET). HIFETs utilise a hygroscopic polymer dielectric that behaves as a solid-state electrolyte, facilitating low voltage (<1 V) operation, in a simple, solution processable, solid-state form factor. Sensitivity to various analytes can be achieved by modifying the top gate electrode with appropriate porous membranes or recognition elements. However, a change to the electrical properties of the gate electrode can significantly degrade transistor characteristics. To better understand this behaviour, we have explored the effect of gate conductance on HIFET performance, using PEDOT:PSS films of varied thickness as a model gate electrode. As gate conductance increases, key figures of merit including ON/OFF ratio, threshold voltage and transconductance improve until approaching a plateau. We understand this effect in terms of a change in the magnitude of the effective gate voltage. These results imply widely applicable design rules, where good transistor functionality can be achieved with a range of gate conductance values that lie in the plateau region, allowing flexibility to incorporate poorly conducting materials that facilitate sensitivity.

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.


Associate Professor Prashant Sonar’s recent work highlighted in media including Brisbane Times and several journal covers

AUCAOS member Associate Professor Prashant Sonar’s research has recently been appeared in a number of publications including the Brisbane Times, as well as on a number of journal covers.

Please follow the links below for more information:

ACS Appl. Electron. Mater.:
https://pubs.acs.org/doi/abs/10.1021/acsaelm.0c00169
(Work highlighted on front cover)

Advanced Electronic Materials:
https://onlinelibrary.wiley.com/doi/abs/10.1002/aelm.202070025
(Work highlighted on front cover)

Advanced Materials:
https://onlinelibrary.wiley.com/doi/epdf/10.1002/adma.202001591
(Work highlighted on front cover)

Chem. Soc. Rev.:
https://pubs.rsc.org/en/content/articlehtml/2020/cs/c9cs00811j
(Work highlighted on back cover)

Brisbane Times Article:
https://www.brisbanetimes.com.au/national/queensland/researchers-see-the-light-by-turning-human-hair-into-oled-displays-20200602-p54yt6.html

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.