Room-Temperature Processed Nb₂O₅ as the Electron-Transporting Layer for Efficient Planar Perovskite Solar Cells

Area of Science:

• Materials Science
• Renewable Energy
• Nanotechnology

Background:

• Traditional electron-transporting layers (ETLs) like TiO2 require high-temperature sintering, limiting their use in flexible perovskite solar cells (PSCs).
• Developing low-temperature processing methods for ETLs is crucial for advancing flexible and energy-efficient PSC fabrication.

Purpose of the Study:

• To demonstrate high-efficiency planar PSCs using room-temperature sputtered niobium oxide (Nb2O5) as an ETL.
• To investigate the properties of amorphous Nb2O5 (a-Nb2O5) and its suitability for low-temperature PSC fabrication.
• To assess the potential of a-Nb2O5 for flexible PSC applications.

Main Methods:

• Fabrication of planar PSCs utilizing room-temperature sputtered amorphous niobium oxide (a-Nb2O5) as the ETL.
• Annealing of crystalline niobium oxide (c-Nb2O5) at high temperatures (500 °C) for comparison.
• Characterization of a-Nb2O5 film properties using Hall effect and Kelvin probe force microscopy.
• Fabrication and testing of flexible PSCs incorporating the a-Nb2O5 ETL.

Main Results:

• Planar PSCs with a-Nb2O5 achieved a power conversion efficiency (PCE) of 17.1% without heat treatment.
• Crystalline Nb2O5 (c-Nb2O5) yielded a similar PCE of 17.2%, highlighting the energy-saving advantage of a-Nb2O5.
• Hall effect measurements revealed high mobility and conductivity in a-Nb2O5 films.
• Kelvin probe force microscopy showed favorable Fermi levels in both a-Nb2O5 (-4.31 eV) and c-Nb2O5 (-4.02 eV) for efficient electron extraction.
• Flexible PSCs based on a-Nb2O5 demonstrated a considerable PCE of 12.1%.

Conclusions:

• Room-temperature sputtered a-Nb2O5 is an effective ETL for high-efficiency planar PSCs, offering significant energy savings.
• The favorable electronic properties of a-Nb2O5 facilitate efficient electron extraction at the ETL/perovskite interface.
• The low-temperature processing capability of a-Nb2O5 makes it highly suitable for fabricating flexible PSCs.
• a-Nb2O5 shows great potential for future applications in low-cost, energy-efficient optoelectrical devices.