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Perovskites for solar energy

 

The goal of this project is to take the perovskite-based solar cell beyond the present day performance level by way of a detailed experimental and theoretical understanding of the charge separation mechanisms. This know-how will feed back into the concept and optimisation of the solar cells delivering improved performance of 18 percent or more.

Project description (ongoing research project)

Organic-inorganic hybrid materials promise both the superior carrier mobility of inorganic semiconductors and the easier processing of organic materials. Hybrid organic-inorganic methylammonium lead-halogen perovskites are recognised for their excellent semiconducting properties. Their conversion efficiency is currently reaching levels above 15 percent. In addition to this excellent photovoltaic performance, the growth and deposition procedures of these materials are also attractive because of their versatility in terms of fabrication methods.

Aim

The project aims to develop and examine high efficiency hybrid organic-inorganic thin film solid-state perovskite solar cells in order to raise the power conversion efficiency above the 15 percent level. In terms of fabrication, the strategy is to concentrate on samples prepared by dual-source vapour deposition, two-step vapour deposition, and vapour-assisted solution processing methods. The characterisation aims at assessing the important aspects of cell operation such as exciton generation, migration and dissociation, or the equivalent for free charges, as well as electron and hole transfer at interfaces using time-resolved optical and core-level spectroscopies from femtoseconds (fs)/picoseconds (ps) to nanoseconds. Photoluminescence and transient absorption studies will be carried out to identify the global charge carrier dynamics. For a finer identification of the fate of charge carriers (holes and electrons), fs/ps X-ray absorption spectroscopy and electron-energy-loss-spectroscopy (EELS) will be used. These studies will be carried out on pure perovskite materials and the complete cell.

Relevance

Developing an efficient thin film solid state solar cell by sandwiching a sublimated CH3NH3PbX3 (X=halogen) perovskite layer between two thin organic charge transporting layers that function as hole and electron blockers and contacting it via a conductive polymer will represent a breakthrough. The expected device power conversion efficiency of 18 percent at 100 mW cm−2 is remarkable. In particular the expected short circuit current of 24 mA cm−2 and the open circuit potential of over 1.0 volts would provide significant benefits for small and medium-sized companies and the Swiss economy.

Original title

Preparation and characterization of high efficiency hybrid organic-inorganic thin film solar cells

Principal Investigators

  • Prof. Majed Chergui, Laboratoire de spectroscopie ultrarapide, EPF Lausanne
  • Prof Ursula Röthlisberger, Laboratoire de chimie et biochimie computationnelles, EPF Lausanne
  • Dr. Mohammad Khaja Nazeeruddin, Laboratoire de photonique et interfaces, EPF Lausanne

 

 

Further information on this content

 Contact

Prof. Majed Chergui Laboratoire de spectroscopie ultrarapide
EPFL - SB - ISIC - LSU
Station 6
Bâtiment CH
1015 Lausanne +41 21 693 04 57 majed.chergui@epfl.ch

Products of the project