Annealing-Free Gradient Doping Strategy to Build Amorphous Nb:TiO_X Electron Transport Layer for Efficient Perovskite...

Area of Science:

• Materials Science
• Renewable Energy
• Nanotechnology

Background:

• Electron transport layers (ETLs) are crucial for efficient perovskite solar cell (PSC) performance.
• Conventional ETL fabrication often requires high-temperature annealing, limiting substrate compatibility and increasing costs.
• Optimizing the interface between ETLs and perovskite absorbers is key to minimizing energy losses.

Purpose of the Study:

• To develop a low-temperature, annealing-free strategy for fabricating niobium-doped titanium dioxide (NTO) ETLs.
• To engineer a vertically graded composition in NTO films for improved energy level alignment and charge extraction.
• To enhance the performance and stability of PSCs using the novel NTO ETLs.

Main Methods:

• Dynamic co-sputtering with controlled power modulation to create vertically graded NTO films.
• Characterization of NTO film morphology, composition, and interface properties.
• Fabrication and testing of PSCs incorporating the compositionally graded NTO ETLs.

Main Results:

• Achieved annealing-free fabrication of NTO ETLs with a vertically graded composition (Ti-rich bottom, Nb-rich top).
• NTO films exhibited smooth, amorphous morphology and chemically homogeneous interfaces.
• PSC devices with graded NTO ETLs reached a power conversion efficiency of 19.9% and an open-circuit voltage of 1.12 V.
• Demonstrated improved open-circuit voltage and fill factor due to minimized recombination losses.

Conclusions:

• The developed dynamic co-sputtering method offers a scalable and thermally benign pathway for high-performance PSCs.
• Compositionally graded NTO ETLs significantly enhance energy level alignment and charge extraction in PSCs.
• This annealing-free strategy paves the way for cost-effective, flexible, and efficient perovskite solar cell technologies.