Reducing Interface Recombination through Mixed Nanocrystal Interlayers in PbS Quantum Dot Solar Cells

Area of Science:

• Materials Science
• Nanotechnology
• Photovoltaics

Background:

• ZnO/PbS colloidal quantum dot (CQD) solar cells suffer from performance limitations due to charge carrier recombination at the heterojunction interface.
• Interfacial recombination is a critical factor hindering efficient charge collection and photocurrent generation in these devices.

Purpose of the Study:

• To investigate the efficacy of a mixed nanocrystal (MNC) buffer layer in mitigating interfacial recombination in ZnO/PbS CQD solar cells.
• To enhance the charge collection efficiency and overall device performance by reducing electron back transfer.

Main Methods:

• Fabrication of ZnO/PbS CQD solar cells incorporating a mixed nanocrystal (MNC) buffer layer composed of zinc oxide nanocrystals and lead sulfide quantum dots.
• Utilizing remote trap passivation within the MNC layer to passivate PbS CQDs.
• Performing optoelectronic characterization to assess device performance and interfacial properties.

Main Results:

• The addition of the MNC buffer layer led to a significant increase in power conversion efficiency, from 9.11% to 10.16%.
• Short-circuit current density (J_SC) improved from 23.54 to 25.23 mA/cm².
• Characterization confirmed reduced trap density and enhanced charge collection efficiency in devices with the MNC layer.

Conclusions:

• The developed MNC buffer layer effectively reduces interfacial recombination and electron back transfer in ZnO/PbS CQD solar cells.
• This strategy offers a viable method for improving the performance of CQD-based photovoltaic devices.
• The findings highlight the potential of MNC buffer layers for next-generation solar cell applications.