The fabrication and analysis of a PbS nanocrystal:C 60 bilayer hybrid photovoltaic system

Abstract

A near-infrared sensitive hybrid photovoltaic system between PbS nanocrystals (PbS-NCs) and C 60 is demonstrated. Up to 0.44% power conversion efficiency is obtained under AM1.5G with a short circuit current density ( J sc ) of 5 mA cm 2 when the PbS-NC layer is treated in anhydrous methanol. The observed J sc is found be approximately one-third of the maximum expected from this hybrid configuration, indicating the potential for further optimization. Crucial for device operation, a smooth film of nanocrystals is seen to form on the hole transporting poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) layer deposited on the transparent electrode, facilitated through an ionic interaction between nanocrystal capping ligands and the PEDOT:PSS. The formation of the open circuit voltage in this system is seen to be influenced by an interfacial dipole formed at the hole-extracting electrode, providing insights for further optimization.