Japanese Researchers Boost Tin Perovskite Solar Cell Efficiency to 9.07% and Longevity with Novel 2-ABZ Additive

EurekAlert! Japan

Overview

Japanese researchers have successfully enhanced the performance of lead-free tin (Sn)-based perovskite solar cells (SnPSCs), which have lower environmental impact. By introducing a novel heteroatom additive, 2-aminobenzothiazole (2-ABZ), into quasi-2D Sn-based SnPSCs, they simultaneously improved efficiency and long-term stability. The optimized device achieved a power conversion efficiency of 9.07% and maintained approximately 89% of its initial performance after 10 hours of continuous operation, marking a significant step towards lead-free alternatives with stability comparable to lead-based devices.

In Depth

Key Findings

A Japanese research team has achieved a breakthrough in significantly improving the efficiency and longevity of environmentally friendly, lead-free tin (Sn)-based perovskite solar cells (SnPSCs). In this study, a novel heteroatom additive, 2-aminobenzothiazole (2-ABZ), was introduced into quasi-2D Sn-based SnPSCs. It was demonstrated that this additive synergistically contributes to controlling crystal growth, passivating defects, and suppressing tin oxidation and iodide migration. The optimized device achieved a power conversion efficiency of 9.07% and, remarkably, maintained approximately 89% of its initial performance after 10 hours of continuous operation in stability tests, demonstrating excellent stability previously difficult for SnPSCs.

Technical & Clinical Details

While SnPSCs are attracting attention as a lead-free alternative to lead-based perovskite solar cells due to their low toxicity, the instability caused by the air oxidation of tin(II) ions and high defect density have been major challenges for efficiency and stability. The 2-ABZ introduced by the research team intervenes in the crystal growth process when added to the perovskite precursor solution. The nitrogen and sulfur atoms in 2-ABZ coordinate with tin ions, delaying crystal nucleation and forming larger, more oriented crystalline grains. This reduces defects in the film (particularly tin vacancies and iodide vacancies) and suppresses non-radiative recombination of charge carriers. Furthermore, 2-ABZ acts as a reducing agent, effectively preventing the oxidation of tin(II) ions to tin(IV) ions, thereby enhancing the long-term chemical stability of the device. Simultaneously, iodide ion migration is also suppressed, reducing current-voltage hysteresis and achieving stable operation. These mechanisms collectively resulted in a PCE of 9.07% and superior operational stability.

Background & Context

Perovskite solar cells are expected to achieve higher efficiencies than silicon solar cells, but the toxicity of lead, a component material, has raised environmental and health concerns. Consequently, research into lead-free alternative materials, particularly tin-based perovskites, has been actively pursued. However, tin-based perovskites have faced challenges of lower efficiency and stability compared to their lead-based counterparts. This research from Japan significantly enhances the performance of tin-based perovskites, holding immense importance for advancing lead-free technology. It not only points towards the direction of sustainable energy technology development but also strengthens the technical foundation for providing environmentally conscious options in the future solar cell market.

Strategic Significance & Outlook

The improvement in efficiency and stability of tin-based perovskite solar cells through 2-ABZ addition represents a significant advancement towards the commercialization of lead-free perovskites. Future research will focus on further performance enhancement by optimizing the additive concentration or combining it with other additives, as well as evaluating reproducibility in large-area devices and long-term outdoor reliability. Although the 9.07% efficiency is not yet on par with the highest efficiency of lead-based perovskites (~26%), the significant improvement in stability is an essential factor for commercial application. This technology is particularly expected to find applications in niche markets requiring flexibility or low-light performance, such as flexible electronics, IoT devices, and indoor solar cells. The progress in lead-free technology is a strategically important step, paving the way for the widespread and environmentally friendly adoption of perovskite solar cells.

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