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A Diphosphonic Acid-Based Interlayer for Highly Efficient and Stable Inverted Perovskite Solar Cells.
Yuanyuan Xu1, Yu Chen1, Lishou Ban1
1Tianjin Key Laboratory of Organic Solar Cells and Photochemical Conversion, School of Chemistry and Chemical Engineering, School of Materials Science and Engineering, Tianjin University of Technology, Tianjin 300384, People's Republic of China.
ACS Applied Materials & Interfaces
|October 21, 2024
Summary
We developed a new interlayer, BINOL-PA, for organic solar cells. This material enhances device efficiency and stability by reducing charge recombination and improving energy level alignment in PTAA-based devices.
Area of Science:
- Materials Science
- Organic Electronics
- Photovoltaics
Background:
- Organic solar cells (OSCs) require efficient charge transport layers to minimize energy losses.
- Interface engineering is crucial for optimizing the performance and stability of OSCs.
- Poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) is a common hole-transporting material in OSCs.
Purpose of the Study:
- To investigate the effect of a novel interlayer, 6,6'-bis(4-(bis(4-methoxyphenyl)amino)phenyl)-[1,1'-binaphthalene]-(2,2'-diyl)bis(oxy)bis(propane-3,1-diyl)bis(phosphonic acid) (BINOL-PA), on the performance of undoped PTAA-based organic solar cells.
- To understand the mechanism by which BINOL-PA improves interfacial properties and device efficiency.
- To evaluate the long-term operational stability of devices incorporating the BINOL-PA interlayer.
Main Methods:
- Fabrication of organic solar cells with and without the BINOL-PA interlayer.
- Characterization of interfacial properties using techniques like ultraviolet photoelectron spectroscopy (UPS) to determine energy levels (Fermi energy to valence band maximum).
- Performance evaluation through current density-voltage (J-V) measurements, open-circuit voltage decay (OCVD), and electrochemical impedance spectroscopy (EIS).
- Stability testing under ambient conditions and thermal aging under nitrogen atmosphere.
Main Results:
- The BINOL-PA interlayer significantly reduced the distance from the Fermi energy to the valence band maximum from 0.95 eV for PTAA alone to 0.36 eV.
- Devices with BINOL-PA/PTAA exhibited enhanced photovoltaic conversion efficiency (PCE) of 21.02% compared to 18% for PTAA alone.
- Improved device parameters including open-circuit voltage (VOC) and fill factor (FF) were observed with the BINOL-PA interlayer.
- The BINOL-PA/PTAA devices demonstrated excellent stability, retaining over 89% of initial PCE after 30 days in ambient conditions and 60% after 1500 hours of thermal aging.
Conclusions:
- The BINOL-PA interlayer effectively suppresses charge recombination and optimizes energy level alignment at the interface.
- The incorporation of BINOL-PA leads to significant improvements in the efficiency and operational stability of organic solar cells.
- BINOL-PA represents a promising material for advancing high-performance and durable organic photovoltaic devices.
