Dipole Orientation in Light-Emitting Films for OLEDs
/In this month’s Fluxim research news:
We take a closer look at dipole orientation in light-emitting thin films for OLEDs in the latest episode of our Fluxim’s Science Shorts. This is a tutorial for all researchers interested in OLED optimization, where we explain how to characterize the OLED active layer with Phelos, and to fit the data with the simulation software Setfos.
Plus keep up to date with:
New Episode of our Fluxim’s Science Shorts
For fans of Fluxim’s Science Shorts be the first to see the latest episode: Dipole orientation in light-emitting films for OLEDs.
In this episode, Dr. Antonio Cabas Vidani explains how the dipole orientation in the emitting layer affects the efficiency of an OLED.
Please watch it and if you have any questions please leave them in the comments section below 😉👇
Angle-dependent PL and EL Measurements in one Table-Top Instrument?
In the video above we briefly mention the gonio-spectrometer Phelos that was used to carry out PL measurements. For those of you working on the development of LEDs for AR/VR headsets, or rollable, foldable, squashable displays then this unique instrument could be of interest.
So why is it unique? Traditional angular-resolved spectrometers are optimized to measure either electroluminescence (EL) or photoluminescence (PL). Phelos incorporates both measuring techniques in one table-top (50 x 29 x 24 cm3) portable instrument.
Check out the video below to see Phelos in action.
So what are the advantages of using Phelos?
We could share a list of advantages (you can read them here) but what could be more convincing than having the thoughts of someone who is currently using it?
Over to Dr. Kumar Sudhir at the Institute for Chemical and Bioengineering, ETH Zürich:
“The Phelos …spectrometer along with Setfos package is a great combination of hardware and software to characterize the orientation of emission transition dipole moment.
The user-friendly interface and a broad range of parameters, such as polarization angles, position angles, driving current, and J-V parameters to investigate the PL as well as EL characteristics of light-emitting semiconductors.
We have extensively used both Phelos and Setfos to understand the quantum emission characteristics of perovskites and organometallic complexes and light-extraction efficiency in PeLEDs and OLEDs.
We found these tools allowed fast data acquisition, simulation, and in-depth understanding of emission characteristics of LEDs and OLEDs”.
How do we use Phelos?
The Fluxim Research Team has been using Phelos extensively, not only to test the capabilities of our instrument but also because it is useful for our research (which is why we built it).
So If you want to understand how to characterize, for example, down-converting nanocrystals for displays you can check this page:
“LIGHT CONVERSION USING PEROVSKITE QUANTUM DOTS”.
We also prepared a tutorial to explain how to combine Phelos and Setfos to perform angular resolved photoluminescence and electroluminescence on organic light-emitting films and devices.
Some Recent Research Papers
Perovskite Solar Modules: Design Optimization
D. Castro, V. C. M. Duarte, and L. Andrade
ACS Omega 2022, 7, 40844−40852
How do you find the best design option for upscaling single solar cells into modules by minimizing electrical losses in the device substrates?
The group of Prof. Luísa Andrade at the Universidade do Porto analyzed efficiency losses in perovskite mini-modules compared to the lab-scale devices. A solar cell of 0.2 cm2 reached an efficiency of 15.22%. This decreased to 8.1% of the mini-module due to the resistance of the TCO and interconnections. A strategy that they suggested to improve the efficiency of the large-area devices is to add a hexagonal gold grid to the TCO.
This ground study was performed with the simulation software LAOSS. LAOSS has been developed to help researchers design optimized mini-modules and large-area solar cells before their fabrication.
A Thiourea Competitive Crystallization Strategy for FA-Based Perovskite Solar Cells
Sun, Q., Tuo, B., Ren, Z., Xue, T., Zhang, Y., Ma, J., Li, P., Song, Y.
Adv. Funct. Mater. 2022, 2208885.
doi.org/10.1002/adfm.202208885
Great experimental success in controlling the crystallization and defect passivation of FAPbI3-based solar cells with the addition of thiourea (TU).
Yanlin Song and colleagues at the Chinese Academy of Sciences embedded TU as a dopant in PbI2 and they used it as interface treatment at the SnO2/perovskite interface. Devices with either of the two treatments presented larger grains, and lower defect concentration.
The treatment released tensile stress in the perovskite by reducing the interface lattice mismatch at the SnO2/perovskite heterojunction. The champion solar cell reached a PCE of 24.4% and retained 80% of the initial efficiency after 120 hours of stressing at 60°C in N2.
Transient photocurrent (TPC), transient photovoltage (TPV), and space-charge limited current (SCLC) were performed with Paios. These experiments confirmed the improvement in charge carrier transport and reduction in recombination thanks to the reduced defect concentration.
High-performance polymerized small molecule acceptor by synergistic optimization on π-bridge linker and side chain
Sun, G., Jiang, X., Li, X. Meng, L, Zhang J, et al.
Nat. Comm. 2022, 13, 5267
https://doi.org/10.1038/s41467-022-32964-z
Polymeric small-molecule acceptors (PSMAs) are narrow bandgap small-molecule acceptors (SMAs) copolymerized with a π-bridge linking unit (linker).
A power conversion efficiency of 17.24% was reached recently at the Beijing National Laboratory of Molecular Sciences by testing three PY-IT derivatives. PG-IT2F was the champion polymer with lower recombination and improved charge transport.
With PAIOS they performed light-dependent transient photovoltage (TPV) measurements and estimated a charge lifetime of 0.769 us on PG-IT2F-based solar cells compared to 0.436 us for the reference PY-IT PVs.
These are just a few of the recent papers published featuring out research tools. There are more and you can access them all here >
December Conferences
The 13th International Conference on Electroluminescence and Optoelectronic Devices (ICEL) is a 3 -day conference in London and is an excellent opportunity for the intellectual and social interactions that make the materials science community so closely connected.
Fluxim’s Stefano Sem will be presenting the following poster at the conference:
Evidence for localized charge trap formation during OLED degradation
The poster session takes place between 15.40 -17.45 on December 5th, 2022.
Next Generation Solar Energy (NGSE) is an international conference series organized by the Friedrich-Alexander University Erlangen-Nürnberg (FAU) and the Helmholtz Institute Erlangen-Nürnberg for Renewable Energies (HI ERN) in December.
The conference, now in its 7th year (NGSE-7) will be held from 6th – 8th of December 2022 in a hybrid format.
Fluxim’s founder Prof. Beat Ruhstaller will be in attendance as an invited speaker.
We are also looking forward to listening to our colleague Dr. Evelyne Knapp from the Zurich University of Applied Sciences who will be giving a talk on Machine-Learning Assisted Parameter Extraction in Solar Cells.
The conference offers an excellent opportunity to learn about the latest developments and current projects in the field of machine learning, high-throughput experimentation, and photovoltaics. As well as the exchange of ideas and experiences with experts from around the world, particularly those who are in close collaboration with i-MEET, HI ERN, and ZAE Bayern.
Career Opportunities at FLUXiM
Wir suchen eine/n ELEKTRONIKER*IN / AUTOMATIKER*IN/ TECHNIKER*IN.
We are currently looking for someone to strengthen our hardware production team. If you (or someone you know) are an experienced electronics, automation, or mechatronics professional with knowledge of PCB development and mechanical design then we may have a place for you.
