We welcome new graduate students and visitors that joined us over the past few months:)
- Sahil Shah, a new Ph.D. student originally from India, will be working on understanding interfacial recombination in perovskite solar cells.
- Karol Peters, a Bachelor student of the University of Potsdam will be working on the automatization of smart measurement routines.
- Kai Oehring, a Master student from the TU-Berlin will be writing his Master thesis the development of novel organic-perovskite tandem cells
- Fangyuan Ye, a Ph.D. candidate from East China University of Science and Technology (ECUST) will join our group for 1 year to work on development of novel charge transport materials and interfacial materials.
Welcome to the group!
Optimization of Monolithic Perovskite/Si Tandems can be tricky and tedious; after all, the monolithic interconnection turns it into a Blackbox, and standard JV measurements under AM1.5 give no feedback on the quality and losses within the two individual subcells. In this work, we develop an advanced EL & PL methodology that allows measurement of sub-cell selective pseudo-light JV characteristics. Those give helpful feedback & deep insights into limiting losses. Kudos to Dr. Eike Köhnen from the Albrecht lab at HZB for this great collaboration and congratulations to Felix Lang!
Lang, F.; Köhnen, E.; Warby, J.; Xu, K.; Grischek, M.; Wagner, P.; Neher, D.; Korte, L.; Albrecht, S.; Stolterfoht, M. Revealing Fundamental Efficiency Limits of Monolithic Perovskite/Silicon Tandem Photovoltaics through Subcell Characterization. ACS Energy Lett. 2021, 3982–3991. https://doi.org/10.1021/acsenergylett.1c01783.
Congratulation’s to Felix Lang, our Feodor-Lynen Return Fellow for winning the Prize for best run up oral contribution at the NanoGe Fall Meeting 2021 (NFM2021).
Congratulations to former group member Christian Wolff for his recent publication in Advanced Energy Materials!
In this work, the charge carrier dynamics was directly probed in complete devices and it was shown that the recombination kinetics is fully consistent with a superposition of first-, second-, and third-order recombination processes, with no admixture of recombination pathways with non-integer order. Under solar illumination, recombination in the studied solar cells proceeds predominantly through nonradiative first-order recombination with a lifetime of 250 ns, which competes with second-order free charge recombination which is mostly, if not entirely, radiative. Results from the transient experiments are further employed to successfully explain the steady-state solar cell properties over a wide range of illumination intensities.
Wolff, C. M., Bourelle, S. A., Phuong, L. Q., Kurpiers, J., Feldmann, S., Caprioglio, P., Marquez, J. A., Wolansky, J., Unold, T., Stolterfoht, M., Shoaee, S., Deschler, F. & Neher, D. Orders of Recombination in Complete Perovskite Solar Cells – Linking Time‐Resolved and Steady‐State Measurements. Adv. Energy Mater. 2101823 (2021). doi:10.1002/aenm.202101823
Jarla Thiesbrummels talk bassed on her work "Universal current losses in perovskite solar cells due to mobile ions" won the Talk award for her contribution to the E-MRS Symposium C "On the origin of current losses in lead-tin perovskite solar cells and beyond".
In this work we investigate the origin of the current losses, using a combination of voltage dependent photoluminescence (PL) timeseries and various charge extraction measurements. We demonstrate that the Pn/Sn-perovskite devices suffer from a reduction in the charge extraction efficiency within the first few seconds of operation, which leads to a loss in current and lower maximum power output.
J. Thiesbrummel, V. M. Le Corre, F. Peña-Camargo, L. Perdigón-Toro, F. Lang, F. Yang, M. Grischek, E. Gutierrez-Partida, J. Warby, M. D. Farrar, S. Mahesh, P. Caprioglio, S. Albrecht, D. Neher, H. J. Snaith*, M. Stolterfoht,*
Today Jonas paper has been accepted at Solar RRL, Congratulations!
In this paper we establish a simulation model that well describes efficient p-i-n type perovskite solar cells and a range of different experiments. We then study important device and material parameters and we find that an efficiency regime of 30% can be unlocked by optimizing the built-in potential across the perovskite layer by using either highly doped (1019 cm-3), thick transport layers (TLs) or ultrathin undoped TLs, e.g. self-assembled monolayers.
J. Diekmann, P. Caprioglio, M. H. Futscher, V. M. Le Corre, S. Reichert, F. Jaiser, M. Arvind, L. Perdigón Toro, E. Gutierrez-Partida, F. Peña-Camargo, C. Deibel, B. Ehrler, T. Unold, T. Kirchartz, D. Neher, M. Stolterfoht* Pathways toWards 30% Efficient Single-Junction Perovskite Solar Cells and the Role of Mobile Ions. Sol. RRL. 2021, Accepted Author Manuscript. https://doi.org/10.1002/solr.202100219
Last week Emilio published his first paper as first author with the Potsdam-Pero Group: "Large-Grain Double Cation Perovskites with 18 μs Lifetime and High Luminescence Yield for Efficient Inverted Perovskite Solar Cells"
In this Article we discussed a high-quality double cation perovskite (MA0.07FA0.93PbI3) with low bandgap energy (1.54 eV). These films exhibit large grains (∼1 μm), high external photoluminescence quantum yields of 20%, and outstanding Shockley–Read–Hall carrier lifetimes of 18.2 μs without further passivation. This was translated into efficient pin-type cells (up to 22.5%) with improved stability under illumination.
E. Gutierrez-Partida, H. Hempel, S. Caicedo-Dávila, M. Raoufi, F. Peña-Camargo, M. Grischek, R. Gunder, J. Diekmann, P. Caprioglio, K. O. Brinkmann, H. Köbler, S. Albrecht, T. Riedl, A. Abate, D. Abou-Ras, T. Unold, D. Neher and M. Stolterfoht*Large-Grain Double Cation Perovskites with 18 μs Lifetime and High Luminescence Yield for Efficient Inverted Perovskite Solar Cells. ACS Energy Lett.
2021, 6, XXX, 1045-1054. pubs.acs.org/doi/10.1021/acsenergylett.0c02642.
Congratulations to Pietro Caprioglio for Publishing a new paper on Bromide segregation (link to the paper). This work investigates halide segregation in methylammonium-free wide bandgap perovskites by photoluminescence quantum yield (PLQY) and advanced electron microscopy techniques. It was demonstrated, that phase segregation and charge funnelling, although harmful for the radiative efficiency of the mixed phase, are essential for achieving high PLQYs, selectively at low energies, otherwise not achievable in non-segregated perovskites with a similar bandgap.
Caprioglio, P., Caicedo-Dávila, S., Yang, T., Wolff, C., M., Peña-Camargo, F., Fiala, P., Rech, B., Ballif, C., Abou-Ras, D., Stolterfoht, M., Albrecht, S., Jeangros, Q., Neher D.* Nano-emitting Heterostructures Violate Optical Reciprocity and Enable Efficient Photoluminescence in Halide-Segregated Methylammonium-Free Wide Bandgap Perovskites. ACS Energy Lett. 2021, 6, XXX, 419–428 . https://doi.org/10.1021/acsenergylett.0c02270
Big congratulations to Amran, Eike and Steve et al. for demonstrating the world-record perovskite/silicon tandem solar cell with a stabilized efficiency of over 29%. This oustanding result was achieved based on a newly-designed carbazole-based self-assembled monolayer (SAM, Me-4PACz), which simultaneously enhanced the hole extraction speed, minimized the non-radiative recombination at the hole-selective interface, lowered the ideality factor of the perovskite cell, and reduced the phase-segregation under illumination. The paper has been published in Science (link to the paper).
Al-Ashouri, A., Köhnen, E., Li, B., Magomedov, A., Hempel, H., Caprioglio, P., Márquez, J. A., ..., Rech, B., Schlatmann, R., Topič, M., Korte, L., Abate, A., Stannowski, B., Neher, D., Stolterfoht, M., Unold, T., Getautis, V. & Albrecht, S. Monolithic perovskite/silicon tandem solar cell with over 29% efficiency by enhanced hole extraction. Science 370, 1300–1309 (2020).
Introducing the new postdoc team that joined over the past few months.
- Vincent coming from Koster's group (University of Groningen, NL) will be working on device simulations and electro-optical measurements.
- Felix coming from Strank's group (University of Cambridge, UK) will be working on working on perovskite for space application, radiation hardness and defects.
- Jonny coming from Snaith's group (University of Oxford, UK) will be working on perovskite for tandem solar cells and interface recombination.
Welcome to the group!
Big congratulations to Dr. Christian Wolff and Dr. Pietro Caprioglio for successfully defending their PhD theses at Uni Potsdam on last Friday and Monday! Two amazing people with two amazing talks combined with outstanding knowledge of perovskites and a significant contribution to the field led to 2x summa cum laude, the highest distinction in Germany. We are very proud of you - you did it!
We wish you both a successful start in your postdocs at EPFL Neuchâtel (Christian) and Oxford (Pietro) and thanks for the great times!
Pacho's paper on bromide-rich wide-gap perovskite solar cells has been published in ACS Energy Letters ( link to the paper )! Congratulations to Pacho!
Peña-Camargo, F., Caprioglio, P., Zu, F., Gutierrez-Partida, E., Wolff, CM, Brinkmann, K., Albrecht, S., Riedl, T., Koch, N., Neher, D. & Stolterfoht, M. Halide Segregation versus Interfacial Recombination in Bromide-Rich Wide-Gap Perovskite Solar Cells. ACS Energy Lett. 2728-2736 (2020). doi: 10.1021 / acsenergylett.0c01104
Shanshan's comparative study on the electro-optical properties of MAPI and triple cation has been recently published in ACS Applied Materials and Interfaces ( link to the paper )! Congratulations to former group member Shanshan!
Zhang, S., Shaw, PE, Zhang, G., Jin, H., Shao, M., Lin, H., Meredith, P., Burn, PL, Neher, D. & Stolterfoht, M. Defect / interface recombination limited quasi-Fermi level splitting and open-circuit voltage in mono- and triple cation perovskite solar cells. ACS Appl. Mater. Interfaces acsami.0c02960 (2020). doi: 10.1021 / acsami.0c02960
If you are interested to get hands on lab experience and work on an exciting new solar cell technology (yes, we are talking about perovskites), you are right here as we are looking for Bachelor and Master students to join our group. Contact Martin Stolterfoht (email@example.com). For further information, have a look at the research activities of the Perovskite Group. (June, 2020).
- Christian and Pietro have submitted their Ph.D. thesis - Whohoo !!! (June, 2020)
Our paper on identification of recombination losses in perovskite solar cells published in Nature Energy has been picked up by several science news webpages.