Direct Measurements of Interfacial Photovoltage and Band Alignment in Perovskite Solar Cells Using Hard X-ray...

Area of Science:

• Materials Science
• Solid State Physics
• Renewable Energy

Background:

• Heterojunctions are crucial for charge extraction in thin-film solar cells.
• Predicting and measuring heterojunction properties in operating devices is challenging due to interface complexity and thinness.

Purpose of the Study:

• To demonstrate a direct measurement technique for band alignment and interfacial electric fields in functional perovskite solar cells.
• To analyze the operating conditions of perovskite solar cell interfaces using advanced spectroscopy.

Main Methods:

• Utilized hard X-ray photoelectron spectroscopy (HAXPES) for direct measurement.
• Developed specialized solar cell device and measurement setup designs.
• Investigated perovskite, hole transport, and gold layers at the back contact.

Main Results:

• HAXPES successfully measured band alignment and electric fields under operating conditions.
• Approximately 70% of photovoltage was generated at the back contact.
• Photovoltage generation was distributed between the hole transport material/gold and perovskite/hole transport material interfaces.

Conclusions:

• The study provides direct experimental evidence of band alignment and electric field distribution in perovskite solar cells.
• The findings offer insights into optimizing heterojunctions for improved solar cell performance.
• HAXPES is a powerful tool for characterizing functional interfaces in optoelectronic devices.