PhD_non theory

Will you also look into the OLED choice?

Now we used the Ir phosphoresecent emitter, which is commercially available but quite expensive (how expensive?)

So my promoter is planning to have a separate PhD project that works on optimizing the OLED, which would ideally have a minimal driving voltage.

Don’t say ‘I think …’ too much

also don’t put your hand in your pocket

What motivates you?

Why did you want to do it?

What I found particularly interesting is that the hypothesis of a self-driven organic upconverter has been demonstrated in a proof-of-concept device. So we know how the concept works, but the absorbance is still a key limitation.

What motivates me is that can use the parts of research that I really enjoy like molecular design, synthesis, characterization to address this. While at the same time being able to contribute to bringing organic upconversion closer to a technology that could eventually be integrated into real devices that use NIR photons that right now are difficult or expensive to detect or exploit.

Why should we fund this project?

I think this project is worth funding because it builds on a concept that only recently has been proven. The bottleneck is red-shifting the absorption, for which we have a concrete strategy in why which we have strong confidence within the group because of the groups expertise and BODIPYs and we also have an example of a similar BODIDPY where the change in donor substituents to a julolidine which is also one of the first things I will do, red-shifted the absorption significantly

At the same time I also believe I’m very well suited given my strong background and strong motivation. Because I really believe, this project could bring Upconversion a step closer to integration into real world applications like photocatalysis or imaging.

So I see this as a project where the scientific question is fundamental, the experimental route is concrete, and there is a realistic opportunity to move an already functioning concept significantly forward towards practical applications.

If we already have funding, why should we give it to you?

couple back to previous card and show why this project should be done (not necessarily about the money)

Why should you do this project?

shown strong persistence as can be seen by my grades

what is your weakness?

My strongest background is on the molecular synthesis side, so at the start of the project I have less experience with the device physics and advanced photophysics. I see that as a current weakness, but also as one of the reasons this PhD is attractive to me. The project and the collaboration between the different groups give me the opportunity to develop that expertise and eventually connect molecular design with device performance myself.

or

A development point for me is long-term research planning. As a master student I was mostly used to planning experiments day-to-day, whereas a PhD requires thinking months ahead and managing several research questions simultaneously. I’m aware of that, and I plan to develop it through structured milestones, relevant training, and by actively learning from my supervisors and more experienced PhD researchers.

What is the real practical valorization of the project?

It means:

“How could the results of this project eventually be turned into something useful outside academia?”

So they are not only asking “Why is the science interesting?”, but rather:

• Can the knowledge lead to a technology, material, device or process?

• Is there potential for patents or IP?

The practical valorization would mainly come from the development of new NIR-absorbing organic materials and the design rules behind them. If we identify BODIPY derivatives that significantly improve the spectral range or efficiency of the upconverter, those molecules or device architectures could potentially be protected through IP. In the longer term, this could be relevant for their integration in the optimized UC stack when they are ready for integration in technologies such as low-cost NIR detection and imaging or photocatalysis.

So the immediate output is fundamental knowledge and improved materials, but there is a clear route toward device integration and eventual technological application.

Do you have an idea about the cost of one full upconversion device? And how would the cost evolve after scale-up?

Nowadays, OLEDs in television screens and cell phones have a comparable amount of layers (maybe a little less, but around 15-20 layers). OLEDs are also made with the same vacuum deposition technique. But OLED screens need lithography to isolate pixels, while our technology allows pixel-less imaging. In principle we also don’t need expensive ITO. We do use it now for ease, but we can replace it in future work with cheaper organic transparent conductors with a little less conductivity. This is OK, because in comparision to an OLED there is not much current running throught the UC anyway.

OLED screens have a cost of about 200-500 EUR/cm². So the expected cost after scale-up should be comparable to current OLED screens or maybe a little less.

The self-driven UC is powered only by the photocurrent generated from weak NIR ilumination, so the current is smaller. The electrical loss in an an electrode depends on its resistance:

V_loss = IR

So if the current I is very small, even an electrode with somewhat higher risistance produces only a small voltage and power loss.

expample: PEDOT:PSS

How much material do you need for the device?

About 100 mg is enough for the initial device optimization. We will first test a new BODIPY in a single-junction OPD, where within one evaporation run we can vary the absorber thickness and composition across 16 substrates where each substrate has 4 ITO electrodes. Meaning we can make 64 OPDs per run.

The thickness is varied by putting a mask on different substrates for different times leading to lower layer thicknesses when screened for longer. Eg. first deposit 10 nm than put a mask over part of the samples, these remain 10 nm. Then deposit another 10nm, the not covered ones become 20 nm, etc. that way veras thicknesses are deposited and the total use is that of the thickets layer in (nm).

Typical OPD layer thickness varies between 15 and 40 nm. In the vacuum deposition machine, we use about 1 mg of organic material (BODIPY:C60 blend) for a layer thickness of 1 nm the material is deposited on an area of 15×15 cm where 4×4 substrates can be covered. this does not mean 1 mg is in that layer because during the process a lot of material is lost on the chamber walls.

If you would like to have different ratios of the BODIPY and C60 in run, you would for example first need to cover 8 substrates and deposit the first ratio on the other 8, and for the other ratio the roles would be reversed en the next ratio can be deposited. But than the total material consumption is the sum of the thickets layers for both ratios.

for a 1:1 ratio of BODIPY:C60 and a layer of 40 nm, you need 20 mg of BODIPY and 20 mg of C60. So if we play it safe 3-4 runs are possible for a 100 mg on which we can measure the properties like

• photocurrent

• V_OC

• dark current

• EQE_PV

form which we can conclude which layer thickness and ratio works best.

So only for the most promising BODIPYs would we scale up synthesis because a complete UC contains 3-4 OPDs and therefor requires around 100 nm total BODIPY thickness, corresponding to roughly 100 mg for a single-stack deposition run.

Differenxe strategic basic research and fundamental research?

Fundamental research is mainly curiosity-driven. The central goal is to generate new scientific knowledge and understanding, even if there is no clearly defined application yet. FWO describes it essentially as research where knowledge generation itself is the objective.

Strategic basic research is use-inspired. You still need fundamental scientific questions and there can still be considerable scientific risk, but from the beginning there should be a credible route toward a future economic or societal application—for example a new material, product, process, service, platform or technology. It does not need to become a commercial product during the PhD; the application can be long-term.

Why did you apply for strategic rather than fundamental research?”, I would answer:

“Because the project contains fundamental molecular and photophysical questions, but those questions are not investigated purely out of curiosity. From the start, our molecular design is guided by a clear technological objective: developing NIR absorbers that can improve the performance and spectral range of an organic upconversion device. So it is fundamental research with a clear long-term application perspective, which fits strategic basic research.

Finality of the project

Within the strategic basic research fellowships, we distinguish between applications with an economic or societal finality. The choice of finality will determine how the application potential in the project description should be written, how you should think strategically and which panel members will assess your application, therefore the correct choice is important. If mainly for-profit organizations will benefit from the research outcomes, then the finality is an economic one. If mainly not-for-profit organizations will benefit from the research outcomes, then the finality is a societal one. In case both profit and not-for-profit organizations could profit, the choice should be based on where the largest benefits are to be expected.

• We indicated Economic finality

research stays

At this preparatory stage, two short research visits are envisaged within my Ph.D. period to acquire additional knowledge and gain experience abroad. I will spend some time (~1 month in year 2) at Swansea University with Prof. Paul Meredith to enhance my knowledge on detailed OPD analysis and the fundamental limits of organic photodetection. Our group has previously sent another Ph.D. student (Sam Gielen) to Swansea, and this collaboration has been highly rewarding (with 2 papers in Advanced Materials and 1 in Nature Photonics). On a later stage, near the end of year 3, I would like to visit the group of Prof. Victor de la Pena O’Shea at the IMDEA Energy Institute in Madrid to get familiar with the requirements for (up-conversion-based) photoelectrochemical cells (as envisaged in one of the demonstrators targeting photocatalytic hydrogen evolution). This type of research is well-established in Madrid, and there have been previous contacts with Prof. de la Pena O’Shea (in the framework of the postdoc project of Dr. Sonny Brebels), who is very open to hosting students.

I have not applied for formal approval from the host organizations yet. The exact timing will obviously depend on the progress of my Ph.D.

for the final UC device:

For the final upconverter, we use the same substrate format. In one deposition run, we can fabricate devices with different numbers of stacked OPDs by selectively covering rows during the evaporation process.

For example, we first deposit one OPD on all rows. We then cover the first row and deposit a second OPD on the remaining rows. Next, we cover the second row as well and deposit a third OPD on the remaining rows, and so on. In this way, a single run can contain devices with one, two, three and four OPDs.

This allows us to directly determine how many OPDs are required to generate sufficient photovoltage to drive the OLED, without performing separate deposition runs for each stack configuration. The total BODIPY-related material consumption for such a run is roughly equivalent to 50–100 nm of deposited material, corresponding to about 50–100 mg in our evaporation setup.

a substrate is probabl