Decoding Fluorine Peripheral Substitution Impact in Zinc Phthalocyanines for Perovskite Solar Cells

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• Molecular semiconductors are crucial for advanced electronic devices.
• Zinc phthalocyanines are promising candidates for semiconductor applications.
• Optimizing molecular design is key to enhancing semiconductor performance.

Purpose of the Study:

• To design and synthesize novel zinc phthalocyanine derivatives for use as molecular semiconductors.
• To investigate the structure-property relationships of these derivatives.
• To evaluate their performance in perovskite solar cells.

Main Methods:

• Synthesis of six zinc phthalocyanine derivatives (ZnPc-1-ZnPc-6) with varying peripheral substituents.
• Characterization of their solubility, energy levels, and thin-film morphology.
• Fabrication and testing of n-i-p perovskite solar cells using these derivatives as hole-selective layers.
• Theoretical and experimental assessment of electro-optical properties.

Main Results:

• ZnPc-2, featuring tert-butyl and trifluoroethoxy groups, exhibited favorable energy level alignment, improved thin-film coverage, and high conductivity.
• Perovskite solar cells incorporating ZnPc-2 achieved power conversion efficiencies comparable to Spiro-OMeTAD.
• ZnPc-2 demonstrated good ambient operational stability, retaining 80% of its initial maximum power point current over 24 hours without encapsulation.

Conclusions:

• Molecular design significantly influences the properties of zinc phthalocyanine derivatives and their performance in devices.
• The specific combination of three tert-butyl groups and a trifluoroethoxy arm in ZnPc-2 leads to superior performance.
• ZnPc-2 is a viable alternative hole-selective material for efficient and stable perovskite solar cells.