"Photophysics and BHJ solar cells based on porphyrin and bodipy conjugated polymers"

Vous êtes cordialement invités à la conférence : "Photophysics and BHJ solar cells based on porphyrin and bodipy conjugated polymers", du Pr.Pierre D.HARVEY, Université de Sherbrooke, Faculté des Sciences, Dpt. Chimie, organisé par l'IPCMS
 

Abstract:
Bulk heterojunction (BHJ) solar cells containing small molecules, oligomers and conjugated polymers are still a very active field of research simply because of their cheap processing and that the reported photocurrent efficiencies, PCE, although modest in comparison with inorganic devices, of the newly designed devices are still increasing year after year. Concurrently, the design of so-called “push-pull” molecules and conjugated polymers used in the active layer played one of the determining roles in the recent developments and improvements in BHJ solar cells. Porphyrins and bodipy’s (boron dipyrromethene’s), although known to be extremely common, were not relatively extensively used in comparison with other chromophore species, until now. This lack of past interest for these pigments for the fabrication of BHJ solar cells was probably driven by the relatively poor PCE values for earlier designs. During this same period, photophysical studies of molecular models containing porphyrin and bodipy species covalently attached to various electron acceptors, including fullerene derivatives, appeared in the literature with the about same frequency as designs of new improved BHJ solar cells were reported. These studies provided various information such as the spectral overlap with the solar spectrum and time scales for the basic photophysical events for isolated molecules. This presentation describes the photophysical events (antenna effect; photo-induced and back electron transfer) occurring in models and in BHJ solar cells, along with the design of BHJ solar cells exhibiting record high PCE’s for “push-pull” oligomers and polymers containing these dyes. Comments about morphology improvement (i.e. thermal annealing, solvent vapour annealing, and addition of solvent) leading to increased PCE’s will also be made.