Nanooptics Group - Faculty for Chemistry and Pharmacy
CENS
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Perovskite thin films

Hybrid organic-inorganic perovskites have drawn a great deal of attention in the last decade due to dramatic strides in power conversion efficiencies (PCEs) as photo-absorbers in solar cells. It is noteworthy that such a growth of the PCE has actually taken decades for other photovoltaic solar cells to accomplish as seen in PCE chart below. This unexpected breakthrough and rapid evolution of this family of materials (seen below, left) have energized not only the photovoltaic community but also the efforts of other optoelectronic communities dealing with devices such as photodetectors, field effect transistors, and lighting devices to create devices from these constituents. A major feature of perovskites that has brought this success is the similarity to the gold standards of crystalline silicon and GaAs semiconductors, including a sharp band gap close to the ideal value, high absorbance, crystalline film formation with low defect densities, balanced electron-hole transport and excellent charge carrier mobilities.

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Our goal is to understand intrinsic features of this family of materials such as mobility and diffusion of charge carriers as well as charge recombination processes in thin films. Additionally, our spectroscopic techniques can reveal not only the role of grain boundaries in thin films but also the chemical compositions at the surface. Below you can find selected publications related to these topics.

  • Using time-resolved PL microscopy, we visualize the ambiplor diffusion of photo-generated charge carriers on sub-micrometer length scales in time. We investigated the influene of grain boundaries in films consisting of large crystals and found that while the restrict carrier diffusion, the do not lead to significant quenching [3]. Temperature dependent measurements allowed us to distinguish the transport limiting factors and the influence of structural disorder occuring at a phase transition [1,2].
  •  Transient-photocurrent (Time-of-flight) measurements allow us to determine the mobility of electrons and holes [4, 6-8].
  • Nano-FTIR: Chemical composition at the surface.

Publications:

  1. Alexander Biewald, Nadja Giesbrecht, Thomas Bein, Pablo Docampo, Achim Hartschuh, Richard Ciesielski, "Local disorder at the phase transition interrupts ambipolar charge carrier transport in large crystal methylammonium lead iodide thin films", J. Phys. Chem. C (2020)
  2. Alexander Biewald, Nadja Giesbrecht, Thomas Bein, Pablo Docampo, Achin Hartschuh and Richard Ciesielski, "Temperature dependent ambipolar charge carrier mobility in large crystal hybrid halide perovskite thin films", ACS Appl. Mater. Interfaces 11, 20838 (2019)
  3. Richard Ciesielski, Frank Schäfer, Nicolai F. Hartmann, Nadja Giesbrecht, Thomas Bein, Pablo Docampo and Achim Hartschuh, "Grain Boundaries Act as Solid Walls for Charge Carrier Diffusion in Large Crystal MAPI Thin Films ", ACS Appl. Mater. Interfaces 10, 7974 (2018)
  4. Nadja Giesbrecht, Johannes Schlipf, Johannes, Irene Grill, Philipp Rieder, Vladimir Dyakonov, Thomas Bein,  Achim Hartschuh, Peter Mueller-Buschbaum, Pablo Docampo, "Single-crystal-like optoelectronic-properties of MAPbI(3) perovskite polycrystalline thin films"  J. Mater. Chem. A 6, 4822 (2018)
  5. Yinghong Hu, Eline M. Hutter, Philipp Rieder, Irene Grill, Jonas Hanisch, Meltem F. Aygüler, Alexander G. Hufnagel, Matthias Handloser, Thomas Bein, Achim Hartschuh, Kristofer Tvingstedt, Vladimir Dyakonov, Andreas Baumann, Tom J. Savenije, Michiel L. Petrus, and Pablo Docampo, "Understanding the Role of Cesium and Rubidium Additives in Perovskite Solar Cells: Trap States, Charge Transport, and Recombination", Adv. Energy Mat. 8, 1703057 (2018)
  6. Irene Grill, Meltem Aygüler, Thomas Bein, Pablo Docampo, Nicolai Hartmann, Matthias Handloser and Achim Hartschuh, "Charge transport limitations in perovskite solar cells: The effect of charge extraction layers", ACS Appl. Mater. Interfaces 9, 37655 (2017)
  7. Irene Grill, Kathrin Handloser, Fabian C Hanusch, Nadja Giesbrecht, Thomas Bein, Pablo Docampo, Matthias Handloser and Achim Hartschuh, "Controlling crystal growth by chloride-assisted synthesis: Towards optimized charge transport in hybrid halide perovskites", Solar Energy Materials and Solar Cells 166, 269-275 (2017)
  8. Andreas Binek, Irene Grill, Niklas Huber, Kristina Peters, Alexander G. Hufnagel, Matthias Handloser, Pablo Docampo, Achim Hartschuh, and Thomas Bein, "Control of Perovskite Crystal Growth by Methylammonium Lead Chloride Templating", Chem. Asian J. DOI: 10.1002/asia.201501379, (2016)
  9. Kathrin Handloser, Nadja Giesbrecht, Thomas Bein, Pablo Docampo, Matthias Handloser, Achim Hartschuh "Contact-less Visualization of Fast Charge Carrier Diffusion in Hybrid Halide Perovskite Thin Films", ACS Photonics 3, 255 (2016)