Air-stable and efficient inorganic–organic heterojunction solar cells using PbS colloidal quantum dots co-capped by 1-dodecanethiol and oleic acid

PbS colloidal quantum dot (CQD)-sensitized inorganic–organic heterojunction solar cells fabricated by using the PbS CQDs co-capped by the oleic acid (OA) and 1-dodecanethiol (DT) ligand showed better device stability with aging time under ambient conditions without encapsulation. Furthermore, the device performance is better than the cell fabricated from PbS CQDs without DT ligand. The enhancement of performance in OA and DT co-capped systems is investigated by impedance spectroscopy. An upward displacement of the TiO2 conduction band, with a consequent increase of Voc, results in the improved performance when CQD with DT are employed.