Perovskite Solar Cell Materials: Introduction, Structure, Composition, Doping, Defects -Edit RMW-UvA

Summary

In this discussion, Assistant Professor René Williams from the University of Amsterdam explores the remarkable rise of perovskite solar cells, highlighting their rapid increase in power conversion efficiency from 4% in 2008 to 25.5% in recent times. Williams delves into the structural aspects of perovskites, their composition, and the significance of methylammonium lead iodide. He addresses the challenges of stability and the potential of zinc doping to improve performance. The talk underscores the need for a paradigm shift towards methylammonium-free perovskites, suggesting a promising future for these materials in the solar cell market.

Takeaways

• 🌟 Perovskites are a special class of photoactive nanomaterials that have seen a rapid rise in power conversion efficiency for solar cells since their introduction in 2008.
• 📈 The efficiency of perovskite solar cells has increased dramatically from 4% in 2008 to 25.5% in recent times, as shown on the NREL chart.
• 🔬 The general perovskite structure, ABX3, consists of cations A and B and an anion X, with lead and halogens being common elements for solar cell materials.
• 🏗️ Perovskites can be easily synthesized from dissolved salts, such as methyl ammonium iodide and lead iodide, through a simple spin coating and heating process.
• 🌞 These materials have a high absorption coefficient for sunlight and are direct band-gap semiconductors, making them efficient at generating and conducting charges.
• 🔋 The stability of perovskite materials has been a concern, but the addition of zinc and alkyl ammonium additives has been shown to improve stability.
• 🔬 Zinc doping in perovskites is believed to induce lattice strain relaxation, enhance chemical bonding, and reduce defects, thereby improving material properties.
• 🔬 The alkyl ammonium additive is thought to stabilize the crystal structure during the fabrication process and protect the crystals, enhancing the overall performance of the solar cell.
• 🚀 The research on perovskite solar cells is evolving quickly, with a shift towards materials that do not contain methylammonium, which is associated with stability issues.
• 🌐 There is an anticipation for the commercialization of perovskite solar cells, possibly in the form of silicon perovskite tandem cells, indicating a promising future for this technology.

Q & A

What is the significance of the year 2008 in the context of perovskite solar cells?

The year 2008 is significant because it marks the entry of perovskites into the research arena of solar cell materials, starting with a power conversion efficiency of about four percent.

What is the current record efficiency for perovskite solar cells as mentioned in the script?

The current record efficiency for perovskite solar cells mentioned in the script is 25.5%, achieved just last month before the presentation.

What is the perovskite structure and how was it named?

The perovskite structure is a general ABX-3 crystal structure where A and B are cations and X is the anion. It was named after Lev Perovski by Gustav Rose, hence the term 'perovskites'.

Which material was the first to be converted into a solar cell by Miyasaka, as mentioned in the script?

Methylammonium lead iodide was the first material to be converted into a solar cell by Miyasaka.

What is the role of the PTAA layer in a perovskite solar cell device?

In a perovskite solar cell device, the PTAA (poly-triaryl-amine) layer serves as the hole conductor, which helps in the selective conduction of positive charges.

Why is lead a popular choice for the B site in perovskite solar cell materials?

Lead is a popular choice for the B site in perovskite solar cell materials because it contributes to high efficiency devices, although it is not the most popular metal due to its toxicity.

What is the significance of the alkyl ammonium additive in perovskite solar cells?

The alkyl ammonium additive plays a significant role in perovskite solar cells by stabilizing the crystal structure, improving the material properties, and enhancing the crystallinity of the perovskite layer.

How does doping perovskite materials with zinc influence their properties?

Doping perovskite materials with zinc can improve their properties by inducing lattice strain relaxation, enhancing chemical bonding, and reducing the amount of defects, which can lead to higher stability and power conversion efficiency.

What is the role of the titanium dioxide (TiO2) layer in a perovskite solar cell device?

The titanium dioxide (TiO2) layer in a perovskite solar cell device serves as the electron conductor, which helps in the selective conduction of negative charges.

Why is there a need to shift away from methylammonium lead tri-iodide in perovskite solar cell research?

There is a need to shift away from methylammonium lead tri-iodide in perovskite solar cell research due to stability issues and the volatility of methylammonium, which can cause degradation and is considered a less desirable component for long-term stability.

What is the potential future for perovskite solar cells in the market, as discussed in the script?

The script suggests that stable perovskite materials may soon enter the solar cell market, with the potential for silicon perovskite tandem solar cells to be available within a few years, as researched by companies like Oxford PV.