Interface Modification for Energy Level Alignment and Charge Extraction in CsPbI₃ Perovskite Solar Cells

Area of Science:

• Materials Science
• Renewable Energy

Background:

• Interface engineering is crucial for perovskite solar cell (PSC) performance.
• Energy level alignment and charge extraction at interfaces significantly impact device efficiency.

Purpose of the Study:

• To modify the interface between CsPbI3 perovskite and spiro-OMeTAD using trioctylphosphine oxide (TOPO).
• To improve energy level alignment and enhance hole charge extraction.
• To boost the power conversion efficiency (PCE) of inorganic CsPbI3 PSCs.

Main Methods:

• Interface modification using trioctylphosphine oxide (TOPO) dipole molecule.
• Passivation of CsPbI3 perovskite film with n-octylammonium iodide (OAI).
• Transient surface photovoltage (trSPV) technique for charge extraction studies.
• Charge transport simulation.

Main Results:

• Upward surface band-bending induced at the perovskite/spiro-OMeTAD interface by TOPO treatment.
• Improved energy level alignment and enhanced hole charge extraction.
• Achieved open-circuit voltage (Voc) of 1.2 V and PCE over 19% for inorganic CsPbI3 PSCs.

Conclusions:

• TOPO dipole molecule effectively modifies the interface for better energy level alignment.
• Enhanced charge extraction leads to significant improvements in PSC performance.
• The study demonstrates a viable strategy for high-efficiency inorganic CsPbI3 perovskite solar cells.