Synergistic Interface Energy Band Alignment Optimization and Defect Passivation toward Efficient and...

Area of Science:

• Materials Science
• Renewable Energy
• Nanotechnology

Background:

• Electron transport layer-free perovskite solar cells (ETL-free PSCs) offer simplified, cost-effective designs for flexible applications.
• The absence of an ETL in PSCs often results in energy level misalignment at the indium tin oxide (ITO)/perovskite interface, hindering charge transfer and device performance.

Purpose of the Study:

• To address the interface energy level mismatch in ETL-free PSCs.
• To enhance charge transfer, reduce energy loss, and improve the overall performance and stability of ETL-free PSCs through interface engineering.

Main Methods:

• Introduction of a polar nonconjugated small-molecule modifier to the ITO electrode.
• Utilizing photoemission spectroscopy and Kelvin probe force microscopy to verify work function modification and energy level alignment.
• Fabrication and characterization of ETL-free PSC devices with the modified interface.

Main Results:

• The small-molecule modifier effectively lowered the ITO work function and optimized the ITO/perovskite interface energy levels, creating a barrier-free contact.
• Devices exhibited significantly improved performance, with power conversion efficiency increasing from 12.81% to a record 20.55%.
• Enhanced device stability and reduced hysteresis were observed due to interface defect passivation and suppressed charge accumulation.

Conclusions:

• Interface electronic structure engineering via facile electrode modification is a viable strategy for developing highly efficient, stable, and low-cost ETL-free PSCs.
• This approach facilitates the large-area, flexible application of perovskite solar technology.