Carbazole Core-Based Small Molecule as an Effective 4-tert-Butylpyridine Replacement for Perovskite Solar Cells

Area of Science:

• Materials Science
• Renewable Energy
• Photovoltaics

Background:

• 4-tert-Butylpyridine (TBP) is used in spiro-OMeTAD hole transport layers (HTLs) for perovskite solar cells.
• TBP's volatility and tendency to cause lithium salt precipitation and perovskite degradation limit device stability.

Purpose of the Study:

• To develop a stable solid-state additive to replace TBP in perovskite solar cells.
• To enhance the performance and long-term stability of perovskite solar cells.

Main Methods:

• A novel small-molecule additive, CN-CZ, was synthesized and incorporated into HTLs.
• Characterization of CN-CZ's coordination properties, solubility enhancement, and energy level alignment.
• Fabrication and testing of perovskite solar cells using CN-CZ and a TBP-based reference.

Main Results:

• CN-CZ demonstrated stronger Li+ coordination, improving Li-TFSI solubility and HTL film quality.
• Optimized energy level alignment facilitated efficient hole extraction and transport.
• Perovskite solar cells with CN-CZ achieved a 25.8% power conversion efficiency (PCE), exceeding the TBP device's 23.8% PCE.

Conclusions:

• CN-CZ effectively replaces TBP, mitigating issues of volatility and degradation.
• The enhanced HTL properties and energy level alignment contribute to superior device performance and stability.
• CN-CZ represents a promising strategy for developing stable and efficient perovskite solar cells.