Perovskite solar cells, a promising technology for harnessing renewable energy, have gained significant attention due to their exceptional light-absorbing capabilities. However, defects within the crystalline structure of polycrystalline formamidinium lead iodide (FAPbI3), a popular perovskite material, hinder their efficiency and stability. To address this challenge, researchers at the Gwangju Institute of Science and Technology (GIST) have devised a groundbreaking defect passivation strategy. They introduced hexagonal polytype (6H) perovskite into the cubic polytype (3C) FAPbI3, effectively reducing defects and leading to a remarkable improvement in power conversion efficiency (PCE) and operational stability. This innovative approach, detailed in a recent publication in *Nature Communications*, leverages the unique properties of 6H perovskite, which contains a corner-sharing component that effectively suppresses defect formation.
Instead of relying on external chemical reagents, which can negatively impact the perovskite’s crystalline quality, the researchers incorporated 6H perovskite into FAPbI3 by utilizing excess lead iodide and methylammonium chloride. This intervention effectively addressed the dominant defect site (halide vacancies) in the α-phase cubic polytype (3C) FAPbI3. The inclusion of 6H perovskite resulted in enhanced structural integrity and carrier dynamics, leading to an ultralong carrier lifetime exceeding 18 microseconds. The GIST team achieved impressive results, including a PCE of 24.13% for solar cells and a certified PCE of 21.44% for a module, accompanied by long-term operational stability. The researchers believe that this 3C/6H hetero-polytypic perovskite design could represent the closest realization of an ideal polycrystalline perovskite film.
This innovative approach to defect engineering in perovskite holds immense potential for advancing the development of highly efficient and stable perovskite solar cells. The implications are far-reaching, impacting the future of solar energy applications for personal and commercial use, including rooftop solar panels, wearable electronics, and portable chargers. The research underlines the critical role of perovskite solar cells in achieving carbon neutrality and combating global warming. Their efficiency, versatility, and minimal environmental impact make them an essential component of the transition toward a sustainable future.
