Time-Resolved Photoemission to Unveil Electronic Coupling between Absorbing and Transport Layers in a Quantum Dot-Based Solar Cell

• DOI: 10.1021/acs.jpcc.0c06751
• Publication Date: 2020-09-23T13:38:40Z
• Authors: Charlie Gréboval; Prachi Rastogi; Junling Qu; Audrey Chu; Julien Ramade; Adrien Khalili; Corentin Dabard; Tung Huu Dang; Hervé Cruguel; Abdelkarim Ouerghi; Nadine Witkowski; Mathieu G. Silly; Emmanuel Lhuillier
• Keywords: Band bending; Multiple exciton generation; Lead sulfide

Lead sulfide (PbS) colloidal quantum dot-based photodiodes are remarkable structures because of their outstanding optoelectronic performances obtained via engineering. They combine surface ligand engineering to design a p–n junction with all-solution processability. Here, we investigate the electronic structure PbS diode combining static and dynamic photoemissions transport measurements. We show that n-type nature I– capped CQDs shifts valence band away from Fermi level compared thiol-capped nanocrystals. This change in majority carriers can be probed by time-resolved X-ray photoemission spectroscopy (TRXPS). also prove photoinduced binding energy shift depends on nanoparticle chemistry. Finally, demonstrate ability TRXPS selectively probe each side an interface. explore PbS/MoO3 interface used as hole extractor solar cell using this method. layer photosensitizes MoO3 two layers have quasi-rigid electrostatic coupling. identify bending occurring (EDT)/MoO3 limiting factor for device performance suggest strategies overcome limitation.