Redefining PbS Quantum Dot Photovoltaics: p-i-n Devices with Superior Efficiency and Reproducibility

Area of Science:

• Materials Science
• Nanotechnology
• Photovoltaics

Background:

• Diverse photovoltaic device architectures are crucial for enhancing power conversion efficiency (PCE) and enabling tandem configurations.
• While n-i-p architectures are common for PbS CQD solar cells, p-i-n designs have historically shown lower efficiency.
• This limits the advancement and integration potential of p-i-n PbS CQD solar cells.

Purpose of the Study:

• To overcome the efficiency limitations of p-i-n PbS CQD solar cells.
• To leverage the surface tunability of CQDs for improved device performance.
• To establish a robust and scalable platform for p-i-n CQD solar cells, particularly for tandem applications.

Main Methods:

• Anchoring MeO-2PACz SAM molecules onto PbS CQDs via ligand exchange to form a PbS-SAM bridging layer.
• Inserting the PbS-SAM layer between NiOx/SAM and the CQD active layer to create a composite hole transporting layer (HTL).
• Utilizing this composite HTL to passivate interfacial traps and enhance hole extraction.

Main Results:

• Achieved a record PCE approaching 14%, with a certified value of 13.62% for p-i-n PbS QD solar cells.
• Significantly surpassed the previous highest PCE for p-i-n PbS QD solar cells (9.70%).
• Exceeded the current PCE record for n-i-p PbS QD solar cells.
• Demonstrated excellent reproducibility and scalability of the p-i-n configuration.

Conclusions:

• The developed NiOx/SAM/PbS-SAM composite HTL effectively passivates traps and improves hole extraction in p-i-n PbS CQD solar cells.
• The new p-i-n architecture sets a new benchmark for PbS CQD solar cell efficiency, outperforming both previous p-i-n and n-i-p devices.
• This work provides a promising and scalable platform for narrow-bandgap subcells in monolithic tandem solar devices, especially when paired with wide-bandgap materials like perovskites.