Compositional and Interfacial Engineering Yield High-Performance and Stable p-i-n Perovskite Solar Cells and...

Area of Science:

• Materials Science
• Renewable Energy
• Photovoltaics

Background:

• Perovskite solar cells (PSCs) offer promising photovoltaic performance.
• Achieving high power conversion efficiency (PCE) and long-term stability in PSCs remains a key challenge.
• Optimization of perovskite composition and interfacial layers is crucial for device performance.

Purpose of the Study:

• To develop a high-efficiency and stable p-i-n type perovskite solar cell (PSC).
• To investigate the synergistic effects of precursor additives and interfacial layers on PSC performance and stability.
• To scale the optimized PSC architecture for larger-area applications.

Main Methods:

• Optimization of perovskite precursor ink composition, including the addition of formamidinium chloride (FACl) to a "triple cation" Cs_0.05FA_0.79MA_0.16PbBr_0.51I_2.49 (Cs-MAFA) formulation.
• Incorporation of a lithium fluoride (LiF) interfacial buffer layer to reduce recombination losses.
• Fabrication of hole-selective contacts using a self-assembled monolayer (SAM) of [2-(9H-carbazol-9-yl)ethyl]phosphonic acid (2PACz) on ITO electrodes.
• Current-density voltage (J-V) measurements for device characterization.
• Long-term stability testing under maximum power point (MPP) tracking.
• Scaling of the optimized device architecture to larger areas and fabrication of mini-modules.

Main Results:

• A p-i-n type PSC with a 1.63 eV absorber bandgap achieved a record power conversion efficiency (PCE) of 22.3%.
• The enhanced performance resulted from improved perovskite absorber quality, increased open-circuit voltage (V_OC) due to reduced recombination, and high-quality hole-selective contacts.
• Optimized devices demonstrated improved long-term stability, retaining approximately 80% of their initial average PCE after >700 hours of MPP tracking.
• Laser-patterned, series-interconnected mini-modules with a 2.2 cm² active area achieved a PCE of 19.4%.

Conclusions:

• The synergistic combination of FACl additive in the perovskite precursor and LiF interfacial layer significantly enhances PSC performance and stability.
• Robust device architecture and reproducible deposition methods are essential for developing high-performance, stable, large-area PSC modules.
• This work provides a pathway for the commercialization of perovskite solar technology through improved efficiency and longevity.