TiO₂ Electron Transport Bilayer for Highly Efficient Planar Perovskite Solar Cell

Area of Science:

• Materials Science
• Renewable Energy
• Nanotechnology

Background:

• Efficient charge extraction and recombination suppression at the electron transport layer/perovskite interface are critical for high-performance planar perovskite solar cells.
• Titanium oxide (TiO2) is a common electron transport material, but its interface properties can limit device performance.

Purpose of the Study:

• To engineer a novel titanium oxide (TiO2) bilayer with tailored Fermi energy levels for improved electron transport in perovskite solar cells.
• To investigate the impact of TiO2 bilayer deposition order on energy band alignment and device performance.

Main Methods:

• Fabrication of a TiO2 bilayer using a combination of atomic layer deposition and spin-coating techniques.
• Modulation of TiO2 bilayer energy band alignment by controlling the deposition sequence of the layers.
• Fabrication and characterization of planar perovskite solar cells utilizing the engineered TiO2 bilayer as the electron transport layer.

Main Results:

• The TiO2 bilayer demonstrated modulated energy band alignments, including type II band alignment.
• Perovskite solar cells with the TiO2 bilayer exhibited enhanced carrier extraction and suppressed recombination.
• The TiO2 bilayer facilitated effective defect passivation at the interface.
• Champion power conversion efficiencies of up to 16.5% were achieved, representing a ~50% improvement over single-layer TiO2 devices.

Conclusions:

• The developed TiO2 bilayer serves as an effective electron transport layer for high-performance planar perovskite solar cells.
• Tailoring the band alignment of the electron transport layer through bilayer engineering is a promising strategy for advancing perovskite solar cell technology.
• The findings highlight the potential of using TiO2 bilayers with type II band alignment to overcome interfacial limitations in perovskite photovoltaics.