Structure atomiques, les propriétés des électrons et la dynamique aux interfaces de photovoltaïques

par Min-i Lee

Projet de thèse en Physique

Sous la direction de Antonio Tejeda et de Pere Roca i cabarrocas.

Thèses en préparation à Paris Saclay , dans le cadre de École doctorale Physique en Île-de-France (Paris) , en partenariat avec Laboratoire de Physique des Solides (laboratoire) et de Université Paris-Sud (établissement de préparation de la thèse) depuis le 01-09-2015 .


  • Résumé

    Nowadays solar cells are dominated by crystalline silicon p-n junctions because of the device efficiency and mature technological process. However, the price of this technology does not allow to compete currently with fossil energies and alternative systems are being studied, which involve charge dissociation at an interface between two materials. The efficiency of the photovoltaic process depends on the charge transfer at this interface. If the photoactivated electron recombines rapidly with a hole, efficiency decreases as the charge carriers do not reach the external circuit. Efficiency can alternatively be increased by generating several electron-hole pairs from a single incoming photon (multiple exciton generation), which is possible in materials with strong electronic correlation. This PhD will aim to study the electronic relaxation in photovoltaic interfaces by time-resolved photoemission and to correlate it to the interface. We will pay particular attention to interfaces prone to multiple exciton generation. The project will take advantage from the only experimental setup in France allowing the study of ultrafast dynamics in electronic structure. Further experiments will be performed in the French synchrotron SOLEIL and other European synchrotrons. Complementary atomic structure studies will be performed by scanning tunnelling microscopy.

  • Titre traduit

    Atomic structure, electron properties and dynamics at photovoltaic interfaces


  • Résumé

    Nowadays solar cells are dominated by crystalline silicon p-n junctions because of the device efficiency and mature technological process. However, the price of this technology does not allow to compete currently with fossil energies and alternative systems are being studied, which involve charge dissociation at an interface between two materials. The efficiency of the photovoltaic process depends on the charge transfer at this interface. If the photoactivated electron recombines rapidly with a hole, efficiency decreases as the charge carriers do not reach the external circuit. Efficiency can alternatively be increased by generating several electron-hole pairs from a single incoming photon (multiple exciton generation), which is possible in materials with strong electronic correlation. This PhD will aim to study the electronic relaxation in photovoltaic interfaces by time-resolved photoemission and to correlate it to the interface. We will pay particular attention to interfaces prone to multiple exciton generation. The project will take advantage from the only experimental setup in France allowing the study of ultrafast dynamics in electronic structure. Further experiments will be performed in the French synchrotron SOLEIL and other European synchrotrons. Complementary atomic structure studies will be performed by scanning tunnelling microscopy.