Alkyl-Trimethoxysilane Strain-Release Layers for Stabilizing Inorganic Perovskite Solar Cells

Background

Inorganic perovskite solar cells (PSCs) represent a highly promising frontier in renewable energy technologies due to their exceptional light-harvesting capabilities and potential for low-cost manufacturing. Specifically, all-inorganic perovskite architectures utilizing materials like cesium lead triiodide (CsPbI3) as the photoactive layer paired with an inorganic electron transport layer (ETL), such as titanium dioxide, are of significant interest. There is a critical need to develop these advanced photovoltaic devices to achieve high power conversion efficiencies and long-term operational stability, which are essential prerequisites for their successful commercialization and widespread deployment in global energy markets.

Despite their potential, current PSC architectures suffer from severe structural instabilities during fabrication and operation. A primary issue is the interfacial lattice distortion that occurs at the boundary between the perovskite and the ETL. This distortion is driven by a mismatch in thermal expansion coefficients during the necessary high-temperature annealing processes. Consequently, this strain induces interfacial defects and impedes efficient charge transfer. More critically, it accelerates an undesirable polymorphic transformation where the photoactive black β-phase of the perovskite rapidly degrades into a non-conductive yellow δ-phase, drastically limiting the overall efficiency and operational lifetime of the solar cells.

Technology

This advanced solar cell technology integrates alkyl-trimethoxysilane-based strain-release layers (SRLs) at the interface between an inorganic perovskite photoactive layer and an electron transport layer (ETL). The device stack comprises a substrate, transparent conductive layer, ETL, SRL, perovskite layer, hole transport layer, and metal electrode. Utilizing oxysilane derivatives like butyltrimethoxysilane, the SRLs are deposited onto the ETL via a simple immersion process. These specialized layers are engineered to compensate for thermal expansion mismatches occurring during fabrication annealing, effectively mitigating interfacial lattice distortion within the solar cell architecture.

This solution is highly differentiated by its unprecedented ability to resolve critical stability and efficiency limitations in perovskite solar cells. By suppressing depth-dependent lattice expansion and minimizing interfacial defects, the SRL stabilizes the desirable photoactive black β-phase of the perovskite, reducing its transformation into the non-conductive yellow δ-phase by nearly two orders of magnitude. Consequently, this novel interface engineering strategy boosts power conversion efficiency up to 20.1%. Furthermore, it achieves record-breaking operational stability, delivering a T90 lifetime of 1,800 hours under continuous illumination. This approach optimizes charge transfer without altering film morphology, providing a scalable pathway to commercially viable photovoltaics.

Benefits

• Significantly increases Power Conversion Efficiency (PCE) up to 20.1%, along with improved open-circuit voltage and fill factor.
• Dramatically enhances operational stability and device lifespan, achieving record-breaking performance (T90 of 1800 hours) under continuous illumination.
• Mitigates interfacial lattice distortion and thermal expansion mismatches between the perovskite and electron transport layers.
• Stabilizes the desirable photoactive black β-phase of the perovskite, reducing its degradation into the non-conductive yellow δ-phase by nearly two orders of magnitude.
• Reduces interfacial defects and improves charge transfer efficiency without negatively altering film morphology or work function.
• Provides a practical, scalable interface engineering approach that boosts the commercial viability of all-inorganic perovskite solar cells.

Applications

• Commercial perovskite solar panels
• Building-integrated photovoltaics
• Flexible wearable solar electronics
• High-efficiency residential solar arrays
• Lightweight aerospace solar cells

Additional info

Alkyl-trimethoxysilane-based strain-release layers (SRLs) are integrated at the interface between inorganic perovskite photoactive layers and electron transport layers. These oxysilane derivatives mitigate lattice distortion from thermal expansion mismatches. By suppressing depth-dependent expansion and reducing interfacial defects, they stabilize the conductive black β-phase and inhibit transformation into the non-conductive yellow δ-phase. This enhances charge transfer efficiency and extends operational stability under continuous illumination.