Opportunity
Conventional perovskite solar cells (PSCs) have demonstrated impressive power conversion efficiencies surpassing many traditional thin-film technologies. However, these devices suffer from fragile interfaces that challenge long-term stability. Under environmental stresses such as humidity, oxygen, temperature changes, and light exposure, contact points within the cell degrade, leading to declining performance and shortened lifespan. In inverted p-i-n PSCs, fullerene electron transport layers (ETLs) are commonly used, but the perovskite/ETL interface creates deep trap states that cause significant efficiency losses. Furthermore, fullerenes are expensive and exhibit poor mechanical properties, driving the search for alternatives. Metal oxides have been considered as replacements, but depositing them on thermally sensitive perovskite materials typically requires high temperatures that damage the perovskite. Sputtering metal oxides directly onto perovskite can damage the surface, while atomic layer deposition (ALD) can cause undesirable chemical reactions and interface barriers, resulting in device power conversion efficiencies below 1%. These persistent challenges underscore the urgent need for a new approach that eliminates or mitigates these shortcomings, particularly by providing a robust, high-performance electron transport layer compatible with perovskite solar cell architectures.
Technology
This invention introduces a perovskite solar cell featuring an electron transport layer composed of first and second portions of tin oxide (SnO_x) with distinct stoichiometry and thickness. The first portion, typically thinner and with a lower oxygen-to-tin ratio (e.g., x ≈ 1.83), is arranged on the second portion, which is thicker and more oxygen-rich (e.g., x ≈ 1.96). This dual-portion configuration induces oxygen vacancies that enhance carrier transfer between the perovskite active layer and the electron transport layer. A passivation layer comprising a phenylethylamine salt and a perylene diimide-based compound is positioned between the electron transport layer and the perovskite active layer. This passivation layer serves a dual function: it passivates the perovskite surface to prevent direct interaction with defect-bearing tin oxide, optimizing interfacial charge transfer, and it acts as a buffer during ALD deposition by preventing water (the oxygen source) from directly contacting the perovskite. The electron transport layer is deposited via atomic layer deposition with precise control over dosing ratios and purge times to achieve the desired stoichiometry and oxygen vacancy distribution. The perovskite active layer itself is doped with a hole transport material in a single-step deposition, simplifying fabrication. This comprehensive design eliminates the need for fullerene-based ETLs, addresses interfacial chemical reactivity, and facilitates efficient electron extraction.
Advantages
- Achieves power conversion efficiency of at least 25.1% with excellent fill factor (81.8%) and high open-circuit voltage (1.19 V)
- Demonstrates exceptional long-term operational stability with T95 aging lifetime exceeding 2000 hours under continuous illumination at 65°C
- Provides self-encapsulation effect that inhibits moisture and oxygen penetration, maintaining >99.1% initial PCE after 2000 hours of dark storage
- Exhibits outstanding damp heat stability with <3.0% decay after 1000 hours at 85°C and 85% relative humidity without encapsulation
- Shows superior thermal cycling endurance with only ~4.7% degradation after 800 cycles from -40°C to 85°C
- Eliminates expensive fullerene materials, reducing production costs
- Suppresses ion diffusion from perovskite to electrode, maintaining device integrity during operation
- Enables simplified manufacturing through one-step deposition of hole transport material with perovskite
Applications
- Inverted p-i-n perovskite solar cells for high-efficiency photovoltaic modules
- Building-integrated photovoltaics requiring long-term stability under outdoor conditions
- Portable and flexible solar power devices needing robust encapsulation-free operation
- Tandem solar cell architectures where stable wide-bandgap perovskite cells are required
- Industrial-scale solar panel manufacturing seeking cost-effective, durable electron transport layers
- Space and aerospace applications demanding resistance to extreme temperature cycling
