Exploring the Physics and Chemistry on the Perovskite Solar Cells Fabricated by Scalable Slot-Die Coating Process in Ambient Air

Perovskite solar cells (PSCs) are rapidly advancing technologies, consistently improving in terms of power conversion efficiency (PCE) and stability. However, the reproducibility of PCE across PSC devices has often been overlooked. Utilizing the scalable slot-die coating technique, PCEs ranging from 10.21% to 17.05% have been recorded, but a notable spatial distribution of performance across a 4x4 cm substrate has been observed. This variability in efficiency predominantly stems from electrical losses.<br/>To gain a deeper understanding of these losses, our study employed advanced loss analysis techniques, including numerical simulations, to investigate the underlying mechanisms. Our findings suggest that a significant portion of the efficiency reduction can be attributed to an increase in bulk defect density, which directly correlates with the quality of the perovskite layer and influences the recombination process. Additionally, substantial charge carrier transportation losses at the HTL/perovskite interface were identified, linked to the Fermi level pinning mechanism prevalent in low-efficiency devices.<br/>This research has culminated in the development of a chemical passivation strategy that improved the PCE from 13.81% to 18.07%, enhancing reproducibility across batches of devices. These results underscore the importance of broadening our focus beyond individual 'champion' devices to encompass all devices across different batches. Such an approach is critical for improving the reliability of the device fabrication process and achieving reproducible results in perovskite solar cell production.<br/><br/><b>Acknowledgement:</b><br/>This research was also funded in part by National Science Centre, in cooperation with the M-ERA.NET 3 Call 2021 for the grant no. 2021/03/Y/ST5/00233. This project has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No 958174. Calculations were carried out at the Academic Computer Centre (CI TASK) in Gdansk.