Thesis: New strategies to improve the transparency of photovoltaic spatial light modulators for self-powered dynamic glazing

PhD defense: Yuhan ZHONG

Team: MaCEPV

Title: New strategies to improve the transparency of photovoltaic spatial light modulators for self-powered dynamic glazing

Summary: Photovoltaic Spatial Light Modulator (PSLM) is a new class of dynamic glazing technologies and has the potential to be applied to smart windows for controlling indoor solar irradiation and improving the energy efficiency in buildings. A PSLM device mainly consists of a nematic liquid crystal (LC) whose optical properties can be modulated, and organic photovoltaic (PV) multilayers that generates a photovoltage to change the LC orientation without the need of an external power supply. The device transparency is one of the key parameters for smart windows applications. In this thesis, we focused on three strategies to improve the transparency of PSLMs: I) Using a PV layer containing a new high band gap donor and a fullerene acceptor to reduce the photon absorption in the visible. Based on the high band gap material, a semi-transparent PSLM was achieved that operates in a self-powered regime; II) Using anisotropic optical PV layers as “internal polarizers” for PSLMs, that are achieved by high temperature rubbing. The organic solar cells based on rubbed PV layers display a dichroic photovoltaic effect; and III) Replacing the commercial external polarizers with oriented and doped polymer films that can be used as “NIR polarizers”. Combining a self-powered PSLM with “NIR polarizers” increases the transmittance in the visible region while restricting the optical modulation to NIR range.

The jury is composed of: Prof. Müller Christian (Professor, Chalmers University of Technology, Sweden), Dr. DEMADRILLE Renaud (Directeur de Recherche CEA, Institut de recherche interdisciplinaire de Grenoble (lRlG), France), Prof. KACZMAREK Malgosia (Professor, University of Southampton, United Kingdom), Dr. BINIEK Laure (Chargée de Recherche CNRS, Institut Charles Sadron, Strasbourg, France)

Supervisor: Prof. Thomas HEISER (Professeur, Université de Strasbourg) and co-supervisor: Dr. Martin BRINKMANN (Directeur de Recherche, CNRS, Strasbourg).

The defense will be held in English and will take place on June 30th at 9 am in the Amphitheater Grünewald in the Cronenbourg campus, Building No.25.