MgCl₂ passivated ZnO electron transporting layer to improve PbS quantum dot solar cells

Area of Science:

• Materials Science
• Nanotechnology
• Photovoltaics

Background:

• Colloidal quantum dots (CQDs) offer tunable bandgaps for low-cost photovoltaics.
• High-performance CQD solar cells require high-quality electron transporting layers (ETLs) for efficient charge extraction.
• Understanding and optimizing n-type oxide ETLs, including their surface states and optical properties, remains an active research area.

Purpose of the Study:

• To develop a simple passivation method for zinc oxide (ZnO) nanoparticles used as ETLs in CQD solar cells.
• To investigate the impact of magnesium chloride (MgCl2) passivation on ZnO ETLs and their effect on device performance.
• To explore the potential of MgCl2-treated ZnO ETLs for enhancing the efficiency of lead sulfide (PbS) CQD solar cells.

Main Methods:

• Synthesis of MgCl2-passivated ZnO nanoparticles.
• Fabrication of PbS CQD solar cells utilizing the MgCl2-treated ZnO ETL.
• Characterization of device performance, including power conversion efficiency, fill factor (FF), and short-circuit current density (Jsc).

Main Results:

• MgCl2 passivation of ZnO nanoparticles significantly improved CQD solar cell efficiency from 6.3% to 8.2%.
• The treated ETL led to reduced defect states within the solar cell.
• Key performance metrics, including FF and Jsc, showed substantial improvements.
• The MgCl2-treated ZnO ETL demonstrated enhanced optical properties.

Conclusions:

• A straightforward MgCl2 passivation technique effectively enhances ZnO nanoparticle ETLs for CQD solar cells.
• This low-temperature processing method offers a promising strategy for improving device performance and reducing defects.
• The developed MgCl2-treated ZnO ETL is a viable candidate for application in solution-processed tandem solar cells to further boost efficiencies.