Photovoltaic performance enhancement on carbon counter electrode based PbS colloidal quantum dots solar cells with surface trap passivation via post-treatment process

High quality of PbS quantum dots have been directly synthesized for the future commercialization of optoelectronics. However, the surface traps still exist, which limits the photovoltaic performance of quantum dot solar cells. In order to improve the photovoltaic characteristics of quantum dot solar cells based on low-cost carbon counter electrodes, tetrabutylammonium iodide is introduced for a post-treatment strategy to finely adjust the surface traps in quantum dot solar cells, which can improve the quality of quantum dot absorption films and reduce charge recombination traps. The optical absorption and charge separation properties of PbS quantum dot solar cells have been improved under tetrabutylammonium iodide post-treatment. The obtained PbS quantum dot solar cells exhibits superior surface passivation and excellent charge transfer efficiency, which effectively reduce the open-circuit voltage loss and increase the short-circuit current density and fill factor value of the solar cells. As a result, the photovoltaic conversion efficiency of carbon counter electrode based PbS quantum dot solar cells has been enhanced from 5.56% to 6.28% with the tetrabutylammonium iodide post-treatment. This work provides an effective process to further optimize the directly synthesized PbS quantum dots in optoelectronic devices applications.