Femtosecond Spectroscopy of Organic Electronic Materials

We investigate what happens on the ultrashort time scale and ultrasmall length scale in organic and hybrid materials in order to induce macroscopic function in electronic devices, and how this can be optimized. We use a complementary palette of techniques combining time-resolved spectroscopy, pulsed photocurrent methods, terahertz experiments, Stark-effect spectroscopy and device testing.


Nature Materials - News and Views

In February 2017, Natalie’s article “Organic Photovoltaics: Pushing the knowledge of interfaces” was published online on Nature Materials – News and Views. Click here to see the article.


In February 2017, the Chimia issue edited by Natalie on spectroscopy was published! Click here to see this edition entitled “The Power of Spectroscopy”.

ACS Energy Letters

In January 2017, Demetra’s article “Hybrid Heterojunctions of Solution-Processed Semiconducting 2D Transition Metal Dichalcogenides” was published in the journal ACS Energy Letters! Click here to read the article.

Journal of Materials Chemistry C

In January 2017, Jan's article "Charge separation in an acceptor–donor–acceptor triad material with a lamellar structure" was published in the Journal of Materials Chemistry C! Click here to see the article.

Yufei joined the FemtoMat group!

In February 2017 the FemtoMat group has been enriched with a new member. Welcome to Yufei who will be a Post-Doc Researcher of the group for the next year!

ITN news

In January 2017, Benedikt Danekamp from University of Valencia joined us for a two months ITN secondment. Martina, Nikos, Jan and Natalie participated to the Plastic Electronics Winter School in Bergün organized by Natalie Stingelin from Imperial College.

ERC Grant

Natalie has obtained an ERC Starting Grant, which will start in March 2017. The research focus will be about how conjugated polyelectrolytes and organic thin film interact with biological environments. We expect a lot of exciting developments for this project entitled OSIRIS (‘Organic Semiconductors Interfaced with Biological Environments’).

NCCR-MUST Annual Meeting 2017

Demetra, Philipp and Natalie attended the 2017 Annual Meeting of the SNFS-funded National Center of Competence in Research (NCCR) on Molecular Ultrafast Science and Technology (MUST) in Grindelwald. Dimitra gave a talk entitled "Excited-State Dynamics in Solution Processed Few-Layer MoS2 Nanoflakes".

Visit from the University of Oxford

In December 2016, Dr. Josue Hardigree from Oxford visited us to do spectroscopic measurements on the degradation of organic solar cells. He was funded by a short term scientific mission (STSM) of COST Action ‘StableNextSol’.


This fall, Natalie gave talks at the MRS Fall Meeting in Boston and at the Zing Conference for Organic Semiconductors in Croatia. She also visited NIST in Washington DC, where she was warmly welcomed by Dr. Lee Richter.

Journal of Physical Chemistry C

In September 2016, Demetra's article "The role of excitons and free charges in the excited-state dynamics of solution-processed few-layer MoS2 nanoflakes " was published online in the Journal of Physical Chemistry C! Click here to see the article.

Nature Communications

In September 2016, Martina's article "The fate of electron–hole pairs in polymer:fullerene blends for organic photovoltaics" was published online in Nature Communications! Click here to see the article.

Video on FemtoMat Research

Click here to watch the video where Natalie talks about solar cells for the Chemistry Deparement of the University of Fribourg! This was shown at the ceremony for award of Bachelor Degrees.

Marie Sklodowska Curie ITN Project

We are Beneficiary in the Innovative Training Network “INFORM” (INterFaces in Opto-electRonic Thin Film Multilayer Devices). Natalie attended the kickoff meeting in London in October 2015 and the first Program Meeting in February 2016. Nikos Droseros was hired as an Early Stage Researcher of INFORM, and will be working in close collaboration with the other partners of the network on charge transfer across organic-inorganic interfaces. He presented his research at the first Scientific Meeting in London in September 2016.

Future of Chemical Physics

AIP Publishing organized a conference about the future of chemical physics, to which Natalie was invited to present a talk about her views on the future of her field. An editorial about this conference was published in the Journal of Chemical Physics.

Invited talks

This summer, Natalie presented several invited talks, at the European Optical Society Bi-Annual Meeting (EOSAM, TOM 7) in Berlin (http://www.myeos.org/events/eosam2016_tom7), at the Symposium on Solar Light to Chemical Energy Conversion organized by the LightChEC Consortium of the University of Zürich in Les Diablerets, at the summerschool “Perspective on Photonics: Investigating the Route from Materials to Device” in Gstaad, and at the International Conference on Optical, Optoelectronic and Photonic Materials and Applications in Montréal. She was also invited to the Centre of Advanced Materials in Heidelberg for a seminar.


Natalie was invited to review her work about the pBTTT:PCBM solar cell material and the influence of the microstructure on the photophysics of charge generation in Chimia, in a special issue featuring her award of the Grammaticakis-Neumann Prize.

SPIE San Diego 2016

In August, Demetra attended the SPIE conference in San Diego and gave a talk about excited-state dynamics in MoS2 nanoflakes. This exciting conference was co-organized by Natalie together with Artem Bakulin and Robert Lovrincic.

Gordon Research Conference 2016

In June, Natalie and Martina participated to the Gordon conference in Lucca, Italy. Natalie gave a talk entitled "Ultrafast Spectroscopic Investigation of Polythiophenes: From Organic Solar Cells, via Perovskite Photovoltaics to Biosensing" while Martina presented a poster about comparative TA study on polymer and dimer blends

Journal of Materials Chemistry C

In May 2016, Jan’s article “Ultrafast Charge Carrier Dynamics in CH3NH3PbI3: Evidence for Hot Hole Injection into Spiro-OMeTAD ” was published online in the Journal of Materials Chemistry C. Click here to see the article.

Philipp joined the Femtomat group

In May 2016 the FemtoMat group has been enriched with a new member. Welcome to Philipp who will be a Ph.D. student of the group for the next four years!

More prominent guests

We invited Prof. Sunichi Fukuzumi from Japan (Osaka University / Meijyo University / Ewha Womans University) in October 2015, and Prof. Gregory Scholes (Princeton University, USA) visited in March 2016, giving an inspiring lecture about: “Ultrafast Singlet Fission and Coherence for Solar Energy Conversion”.

Schweizer Jugend Forscht

Nikos and Martina were involved in the 2016 and 2015 editions of "Schweizer Jugend forscht", in which Swiss high-school students get the opportunity to be in a research lab for the first time. During a week, the students carried out a little project to discover research in the Banerji group. They investigated different polymeric and perovskites samples by (time-resolved) absorption and emission spectroscopy.

Paul-Rhyner Foundation

As part of the Foundation Council, Natalie organized this year’s Paul-Rhyner talk: “Der Sonne entgegen – mit dem Fahrrad von der Quelle bis zur Mündung der Donau”, given by Dr. Beat Maurer (Dr. iur., Rechsanwalt, Bern).

CECP 2016

Natalie gave an invited talk at CECP 2016 (Central European Conference on Photochemistry) in Bad Hofgastein, Austria.

Christmas dinner

Our group organized this year’s Christmas Dinner of the Chemistry Department. Everybody had a lot of fun and ate a lot of cheese fondue!

Rectorate Visit

We were very proud to welcome the Rector of the University of Fribourg with her team, the Vice-Rectors and the Deans of the various Faculties for a visit of our ultrafast spectroscopy laboratory.

Prof. Alan J. Heeger in Fribourg

On 13th of October, the Nobel Prize laureate in chemistry, Prof. Alan J. Heeger, visited the Chemistry Department of the University of Fribourg. He was the 2015 laureate of the Chaim Weizmann Lectureship and gave an inspiring talk entitled “Creativity, Discovery and Risk – Nobel Prizes Past and Future”. Alan Heeger is professor of Physics and Materials at the University of California at Santa Barbara and he was Natalie’s supervisor during her postdoctoral research.

Visit in Cyprus

At the end of September 2015, Lisa visited Prof. Sophia C. Hayes’ group at the University of Cyprus in Nicosia for two weeks. She learned about Resonance Raman spectroscopy and she performed some measurements on a cationic polythiophene.


Jan and Demetra have participated at the first International Conference on Perovskite Solar Cells and Optoelectronics.  They presented our results on charge transfer and hybrid polymer-perovskite solar cells.

Nikos joined our group!

In October 2015 the FemtoMat group has been enriched with a new member. Welcome to Nikos who will be a Ph.D. student of the group for the next four years!

Grammaticakis-Neumann Prize 2015

The prize is awarded to Natalie for her studies providing insight into photophysical processes of polymeric semiconductors. The prize is given on the occasion of the SCS Fall Meeting in Lausanne on September 4th 2015.

The Journal of Physical Chemistry Letters

In September 2015, Jan’s article “Charge Transfer Dynamics from Organometal Halide Perovskite to Polymeric Hole Transport Materials in Hybrid Solar Cells” was published online in The Journal of Physical Chemistry Letters. Click here to see the article.

Mariateresa's PhD defense

In July 2015, Mariateresa presented her PhD dissertation in the public defense at EPFL and she obtained the title of “docteur ès sciences” under the co-supervision of Natalie and Prof. Moser. Congratulations from the FemtoMat group!

L’Hebdo “Forum des 100”

In May, Natalie participated to the “Forum des 100” organized in Lausanne by the Swiss magazine L’Hebdo. Hundred young personalities who “define” the French part of Switzerland were invited to the forum. They are from different areas of expertise, such as science, sports, art, or economics. Natalie had an interview published in the magazine and a video on their website.

Many visitors in our group!

In the past few months we had the chance to invite many guests to Fribourg, giving talks and lectures. They visited our labs and we had stimulating scientific discussions.

  • Prof. Eric Vauthey, University of Geneva
  • Prof. Anke Krüger, University of Würzburg
  • Prof. Natalie Stingelin, Imperial College
  • Prof. Martin Heeney, Imperial College
  • Prof. Sophia C. Hayes, University of Cyprus
  • Prof. Carlos Silva, Université de Montréal


In March 2015 we hosted two groups of girls from high school for the WINS internships (Women In Science and Technology). For them it was an opportunity to have a close look to high level science in a real laboratory and to discover something about spectroscopy and organic solar cells. Natalie also gave a talk for all the girls about her career.


Our first paper since we are in Fribourg has been published in the Journal of the American Chemical Society. We used a transient Stark signature to directly visualize the motion of charges in organic solar cells. Samples had careful control of the polymer:fullerene microstructure. Click here for more details.

La science appelle les jeunes

Martina was involved in the "Schweizer Jugend forscht" week, in which highschool Swiss students get the opportunity to be in a research lab for the first time. During this week the student carried out a little project inline with her scientific background. Different spin-coated samples were made: neat P3HT and P3HT:PBCM blends with different amounts of the acceptor component. The student was able to observe and understand properties of the materials used by measuring absorption and emission spectra.

MRS Spring Meeting

Natalie will present invited talks at the MRS Spring Meeting in San Francisco (6-10 April) in Symposium W — Light-Matter Processes in Molecular Systems and Devices and in Symposium D — Organic-Based Photovoltaics.


Here is the recorded talk given by Natalie in Montreal at the “Next Generation Solar Conference” in May 2014.