Prof. dr. L.D.A. Siebbeles

Research of Laurens Siebbeles focuses on providing understanding of the nature and dynamics of charge carriers and photoexcited states in materials with potential applications in e.g. solar cells, photodiodes, light-emitting diodes, field-effect transistors and nanoscale molecular electronics. Materials of interest include conjugated polymers, molecular materials, semiconductor nanoparticles, and DNA. Charges and excitons are produced by (ultra)short laser or high-energy electron pulses, and detected by time-resolved optical and microwave or terahertz conductivity techniques. The world-wide unique combination of techniques allows us to monitor the formation, mobility and decay of excitons and charge carriers from the sub-picosecond to the millisecond time domain. The experimental research is supported by theoretical calculations of charge and exciton motion. The information obtained about the relation between material structure and the properties of charges and excitons is used to give direction to synthesis of new materials with improved functionality. The research is carried out with numerous academic and industrial (Toyota, Merck UK, BASF) partners that are involved in synthesis, structural characterization or device development.  

1. Direct photogeneration of multiple excitons in adjacent silicon nanocrystals revealed by induced absorption
   M.T. Trinh, R. Limpens, W.D.A.M. de Boer, J.M. Schins, L.D.A. Siebbeles and T. Gregorkiewicz
   Nature Photonics, 6, 316-321 (2012).
2. Unity quantum yield for charge carrier photogeneration and band-like transport in quantum-dot solids
   E. Talgorn, Y. Gao, M. Aerts, L.T. Kunneman, J.M. Schins, M.A. van Huis, H.S.J. van der Zant, A.J. Houtepen and L.D.A. Siebbeles
   Nature Nanotechnology, 6, 733-739 (2011).
3. Charge mobilities in conjugated polymers measured by pulse-radiolysis time-resolved microwave conductivity: from single chains to solids
   F.C. Grozema and L.D.A. Siebbeles
   J. Phys. Chem. Lett. (Invited Perspective), 2, 2951-2958 (2011).
4. Organic solar cells: two electrons from one photon
   L.D.A. Siebbeles
   Nature Chemistry (Invited News & Views Article), 2, 608-609 (2010).
5. Photogeneration and ultrafast dynamics of excitons and charges in P3HT/PCBM blends
   J. Piris, T.E. Dykstra, A.A. Bakulin, P.H.M. van Loosdrecht, W. Knulst, M.T. Trinh,J.M. Schins and L.D.A. Siebbeles
   J. Phys. Chem. C, 113, 14500-14506 (2009).
6. In spite of recent doubts carrier multiplication does occur in PbSe nanocrystals
   M.T. Trinh, A.J. Houtepen, Juleon M. Schins, T. Hanrath, J. Piris, W. Knulst, A.P.L.M. Goossens and L.D.A. Siebbeles
   Nano Lett., 8, 1713-1718 (2008).
7. Mechanism of charge transport in self-organising organic materials
   F.C. Grozema and L.D.A. Siebbeles
   Int. Rev. Phys. Chem. (Invited Review), 27, 87-138 (2008).
8. High intra-chain hole mobility on molecular wires of ladder type poly(p-phenylenes)
   P. Prins, F.C. Grozema, J.M. Schins, S. Patil,  U. Scherf and L.D.A. Siebbeles
   Phys. Rev. Lett., 96, 146601, 1-4 (2006).
9. Absolute rates of hole transfer in DNA
   K. Senthilkumar, F.C. Grozema, C.F. Guerra, F.M. Bickelhaupt, F.D. Lewis, Y.A. Berlin, M.A. Ratner and L.D.A. Siebbeles
   J. Am. Chem. Soc., 127, 148094-14903 (2005).
10. Charge transport in columnar stacked triphenylenes: effects of conformational fluctuations on charge transfer integrals and site-energies
    K. Senthilkumar, F.C. Grozema, F.M. Bickelhaupt and L.D.A. Siebbeles
    J. Chem. Phys., 119, 9809-9817 (2003).
11. Intramolecular charge transport along isolated chains of conjugated polymers: effect of torsional disorder and polymerization defects
    F.C. Grozema, P. Th. van Duijnen, Y.A. Berlin, M.A. Ratner and L.D.A. Siebbeles
    J. Phys. Chem. B, 106, 7791-7795 (2002).

Edited book

Charge and Exciton Transport through Molecular Wires
Eds. L.D.A. Siebbeles and F.C. Grozema
Wiley-VCH, Weinheim, ISBN 978-3-527-31675-5, (2008).  

Born: 12 February 1963, Amsterdam, The Netherlands

Scientific education 

Past and present positions

Awards

• VICI grant (2004) in the Innovational Incentives Scheme of The Netherlands Organisation for Scientific Research (NWO); prestigious grant of 1250 kEuro for senior researchers that have demonstrated their ability to develop a new line of research and act as a mentor for young researchers.
• Young Chemist grant (2002, NWO); grant of 230 kEuro for excellent young chemists to initiate a new research line.
• Antoni van Leeuwenhoek professorship (2001); honorary early promotion to full professor awarded by TU Delft to excellent, promising young scientists.

Main research activities in the optoelectronic materials group during the past ten years

We have provided understanding of the nature and dynamics of charges and excited states (excitons) in organic materials, semiconductor quantum dots, and DNA. Charges and excitons are produced by (ultrashort) laser or high-energy electron pulses, and detected by time-resolved optical and microwave or THz conductivity techniques. During the past years he installed a picosecond pulsed electron accelerator with funding from an NWO/VICI grant. The combination with time-resolved AC conductivity detection is unique in the world. The experimental research is supported by quantum chemical electronic structure calculations, molecular dynamics simulations and Monte Carlo simulations of charge and exciton motion.

Using the electron accelerator facility the mobility of charges along isolated conjugated polymer chains in dilute solution could be measured. The intrachain charge mobility depends strongly on torsional disorder along a polymer chain. The charge mobility could be enhanced by formation of supramolecular ladder structures to achieve a record intrachain mobility as high as 600 cm²/Vs (Phys. Rev. Lett. 96, 146601, (2006))

We developed a method to calculate electronic couplings involved in charge transport through molecuar materials(J. Chem. Phys. 119, 9809 (2003); Int. Rev. Phys. Chem. 27, 87 (2008)). This method has been implemented in the Amsterdam Density Functional (ADF) program. It was used to provide explanations for measured effects of nucleobase sequence on charge transfer through DNA. One of our papers on this topic (JACS 127, 148094 (2005)) was recognized as a 'hot paper' in terms of immediacy of citations.

In recent years we extended our research to (ultrafast) laser spectroscopic studies on exciton dynamics in semiconductor quantum dots (QDs). Conclusive evidence for the production of two or more excitons by the absorption of a single photon in PbSe QDs has been provided (Nano Lett., 8,1713(2008)). The efficiency of this carrier multiplication (CM) process was an issue of hot debate in the literature, due to its importance for development of highly efficient solar cells. Our recent papers on charge carrier photogeneration and CM in thin films of QDs (Nature Phot. 6, 316 (2012); Nature Nanotech. 6, 733 (2011)) have been highlighted by others in Nature Materials (10, 808, (2011)) and Nature Photonics (6, 272, (2012)).

Selection of invited presentations

• Breakthrough solar cells,
  Green Aruba Conference 2012, Aruba, 5-7 Oct. 2012.
• Formation and dynamics of multiple electron-hole pairs in quantum dots,
  Quantsol 2012, Bad Gastein, Austria, 11-16 March 2012.
• Dynamics of excitons and charges in organic materials and semiconductor quantum dots,
  Materials Research Society Fall Meeting, Boston, 28 Nov. - 2 Dec. 2011.
• Dynamics of excitons and charges in polymer/fullerene/quantum dot blend films,
  Gordon Conf. on Electronic Processes in Organic Materials, Mount Holyoke, USA, 25-30 July 2010.
• Interfacial charge generation in polymer/fullerene/quantum dot blend films,
  Gordon Conf. on Radiation Chemistry, Proctor Academy, Andover, USA, 18-23 July 2010.
• Multiexciton generation and nature of excited states in PbSe quantum dots,
  European Materials Research Society Spring Meeting, Strassbourg, France, 8-12 June 2009.
• Fundamental studies of charge and exciton dynamics in conjugated organic materials,
  Excited State Processes in Electronic and Bio and Nano-Materials, Santa Fe, NM, USA, 1-4 Oct. 2007.
• High intra-chain hole mobility on molecular wires of ladder type poly(p-phenylenes),
  Spie Optics and Photonics, San Diego, USA, 13-17 August 2006.
• Dynamics of charge carriers and excitons in organic materials for opto-electronic applications,
  Gordon Conf. on Electronic Processes in Organic Materials, USA, 25-30 July 2004.
• Charge transfer in pi-stacked systems including DNA,
  12^th Int. Congres on Radiation Research, Brisbane, Australia, 18-22 August, 2003.