Refining Perovskite Heterojunctions and Investigating Their Enhanced Aromatic Conjugation for High-Performance Photovoltaic Devices

Photovoltaic (PV) technology has emerged as a crucial solution to the energy crisis in the modern world. In Hong Kong, solar cells are expected to contribute 3-4% of the city's total electricity consumption by 2030, highlighting the importance of their development. Perovskite solar cells (PSCs) have shown remarkable progress, achieving certified efficiencies exceeding 26% while demonstrating improved stability. Consequently, they are considered the most promising thin-film PV technology for commercialization, not only in Hong Kong but also worldwide. However, the stability of perovskite materials still falls short of the requirements for large-scale commercial use. One viable approach to address the stability issue is through the fabrication of low-dimensional/three-dimensional (LD/3D) heterojunctions. Nevertheless, LD perovskites face challenges such as poor charge transport and large exciton binding energies, which hinder their application in photovoltaic devices. Therefore, reducing the bandgap and enhancing carrier transport within LD perovskites are crucial objectives. Although some research groups have reported success in tuning the bandgap of LD perovskites, inadequate charge transport remains a limiting factor in achieving high-performance PSCs. This project aims to explore the use of spacer organic cations in LD perovskites to overcome the poor charge transport issue in LD/3D PSCs. The main challenge lies in reducing the energy barrier between the [PbI6] plane and the large organic cation, while simultaneously enhancing carrier mobility within the organic layer and maintaining hydrophobicity and stability. To tackle this challenge, we propose the development of high-performance LD perovskite materials with strong aromatic conjugation, which can enhance charge transport and photovoltaic efficiency. The research will involve the design and synthesis of stable LD perovskite materials with excellent photoelectric properties. Additionally, the charge carrier dynamics of these LD perovskite materials will be investigated to guide the optimization of the LD structure. Finally, the stability of the integrated perovskite solar cells will be evaluated under moisture and oxygen conditions to assess their performance in real-world applications. The principal investigator (PI) possesses extensive experience in fabricating high-performance PSCs, including expertise in perovskite growth, interfacial engineering, synthesis of charge transporting materials, and defects passivation. The PI's laboratory is equipped with state-of-the- art facilities for device fabrication and characterization, ensuring the successful execution of this project. The successful completion of this research will provide practical and effective methods for extending the absorption capabilities of LD perovskites, thereby facilitating the production of high-performance LD/3D perovskite solar cells. This outcome will greatly benefit the academic and industrial communities in Hong Kong and worldwide.