Green Solvent-Based Perovskite Precursor Development for Ink-Jet Printed Flexible Solar Cells

Within a decade, perovskite solar cells (PSCs) leaped to the forefront of photovoltaic research, rapidly moving toward the industrial phase. Despite the impressive progress in technology development and new efficiency records, there still remains a large scope for further advancement. Utilization of scalable deposition methods and good control of the perovskite crystallization process, especially with industrially compatible fabrication protocols, require more understanding to ascertain reproducible, large-format manufactur-ing. Her; we report ink formulation development for ink-jet printing of perovskite thin films in ambient conditions. We used the precursor solution on a nonhazardous solvent system, fulfilling industrial requirements. By carefully adjusting the coordination environment of the Pb2+ through additive engineering, we were able to tune the nucleation process and achieve uniform, pinhole-free perovskite thin films. Furthermore, we combined multiple characterization techniques with computational methods to analyze Pb-complex structures and evaluate their influence on perovskite formation. Lastly, we applied ink-jet printed photoactive layers into large-area (1 cm(2)) photovoltaic devices and processed on flexible substrates (PET foil). Inverted (p-i-n architecture) PSCs, based on multication composition, Cs-0.1[(HC(NH2)(2))(0.83)(CH3NH3)(0.17)](0.9)Pb-(I0.83Br0.17)(3), delivered 11.4% of power conversion efficiency.