Scalable fabrication of efficient p-n junction lead sulfide quantum dot solar cells

Nowadays, the best lead sulfide (PbS) colloidal quantum dot (CQD) solar cells are primarily demonstrated in the n-p structure, while the p-n structure is significantly less developed. This technological gap between the n-p and p-n structures is much more distinct than in cases of other solution-processable photovoltaic technologies like perovskites and polymers. Here, we propose a scalable fabrication strategy for efficient PbS QD solar cells with p-n structure. An industrially suited blade-coating technique has been used to deposit both n-type and p-type QD layers. The obtained solar cells demonstrated power conversion efficiency of 9%, thus, commensurate to the record device efficiency with this architecture fabricated with a non-scalable technique. The availability of both p-n and n-p structures fabricated from scalable methods may promote the future integration of the PbS QDs into tandem devices together with other solution-processable materials to exploit the most prominent benefits of the PbS QDs, such as infrared absorption.