New Development on Ambient Fabrication of Efficient and Stable Perovskite Solar Cells

Perovskite solar cells have emerged as among the most competitive photovoltaic technologies of the future thanks to their superb and rapidly improving power conversion efficiencies. However, commercialization of the perovskite photovoltaic relies on the development of low-cost and scalable fabrication technologies. In this contribution, I will present the recent development of our laboratory on innovating high-efficiency and high-stability perovskite solar cells. In particular, I will address the fundamental chemical interactions between water and the perovskite precursor components with a view to facilitating perovskite fabrication in ambient atmosphere. We found that the ambient water could promote the formation of lead complexes, which when uncontrolled would make their way into large intermediate fibrillar crystallites and thus discontinuous perovskite films unfavorable for photovoltaics among others. To counter or even overturn this negative effect of water, we propose an effective prenucleation strategy, which embodies the controlled burst of profuse intermediate nuclei and the preventive measure for the crystallite size control during the spin coating process. Consequently, we are able to obtain a compact and uniform perovskite layer, and the solar cells fabricated based thereupon achieved a state-of-art power conversion efficiency of 19.5%. More excitingly, the device showed high performance uniformity, demonstrating the distinctive advantages of our prenucleation strategy. Implications of these results on the future development of reliable and cost-effective fabrication methods for industrial production of perovskite solar cells will be discussed.