Increased open-circuit voltage in a Schottky device using PbS quantum dots with extreme confinement

Abstract

We fabricated the PbS nanocrystal quantum dots (NQDs) based Schottky structure device (ITO/PbS/LiF/Al) with varying bandgap of NQDs from 0.8 to 2.2 eV. The open-circuit voltage increased monotonically with NQD's bandgap until 0.67 V, achieved using extremely confined, 1.5 nm sized-PbS NQDs. The power conversion efficiency reached the maximum value over 3% under AM 1.5 with NQD's bandgap of about 1.3 eV. Size-dependent photovoltaic evaluation in extreme confinement regime provides basis for efficient multi-junction solar cells composed of PbS NQDs of different sizes.