The global energy crisis is a major challenge, especially with the growing demand for digital connectivity and the Internet of Things. Fossil fuels, our main energy source, are running out and causing serious environmental harm. This reality makes the transition to renewable energy not just a priority but a necessity. Solar energy, particularly through photovoltaics, offers a promising solution. While traditional silicon-based solar cells are effective, they come with high costs and environmental difficulty due to energy-intensive production processes. This has led to a search for new materials that can improve both efficiency and sustainability [1].

In this context, perovskite solar cells (PSCs) have emerged as a potential game-changer. These organic-inorganic halide materials offer remarkable optoelectronic properties—high absorption coefficients, long carrier diffusion lengths, and a high tolerance for defects. As a result, PSCs have seen rapid advancements in recent years but unfortunately PSCs degrade in the presence of moisture, oxygen, heat, and light, which limits their commercial viability and long-term performance.

This research aims to develop and investigate novel self-assembled monolayers (SAMs), as electron-selective contacts (ESCs) in PSCs. By leveraging the self-assembly process, these molecular layers offer precise energy level tuning, efficient charge extraction, and improved chemical passivation, promising enhanced stability and scalability. Traditional metal oxide ESCs such as TiO₂ and SnO₂ are limited by high-temperature deposition, poor reproducibility, and increased device hysteresis [2]. In contrast, electron-selective SAMs can facilitate rapid, scalable, and low-temperature processes while minimizing device hysteresis. Furthermore, self-assembled molecules provide an opportunity to reduce the thickness of electron-selective contacts, offering a more efficient charge extraction and potentially enhancing the overall solar cell efficiency. SAMs are also known for forming highly ordered, defect-free layers, which could increase the long-term stability of PSCs, a current limitation in this technology[3].

This work focusses on the design, synthesis, and characterization of electron-transporting SAMs, optimizing their integration into PSCs, and evaluating their performance under various environmental conditions. Key tasks include developing cost-effective synthetic methods for SAMs with phosphonate linkers, comprehensive characterizing their structure and purity, and integrating them into device structures, to optimize film thickness, deposition methods, and perovskite composition to improve power conversion efficiency and long-term stability. Extensive testing will assess the SAMs impact on performance and device stability, with a focus on efficiency degradation and optimal film thickness.

In summary, this research focuses on a novel approach to electron transport in PSCs, focusing on the use of SAMs to replace conventional metal oxide layers. By improving device efficiency, stability, and scalability, advancing the commercialization of perovskite solar cells, contributing to cleaner, more sustainable energy solutions.