Figure 5From: Modification of hybrid active bilayer for enhanced efficiency and stability in planar heterojunction colloidal quantum dot photovoltaicsXPS spectra of Pb 4 f core levels to identify oxidized species. (a) CTAB-treated PbS CQDs film (0 day), (b) OA-treated PbS CQDs film (0 day), (c) CTAB-treated PbS CQDs film (3 days), and (d) OA-treated PbS CQDs film (3 days). The dark curve is the original data and the orange asterisk is the superposition of fitted peaks. Peaks are indicated for elemental lead (red squares), lead in PbS (orange circles), lead in PbS linked to capping ligands (green triangles), and lead in PbSO x (blue stars).Back to article page