Quantitative Deposition Enables Dual Passivation Synergy for Efficient Inverted Perovskite Solar Cells

Non-radiative recombination at the perovskite/C₆₀ interface is a primary culprit for the performance loss in inverted perovskite solar cells (PSCs). While integrated chemical and field-effect passivation presents a promising solution, the lack of precise deposition control has hindered the optimization of this combined effect. Here, we achieve quantitatively controlled and uniform deposition of 1,3-propyldiammonium diiodide (PDADI) by employing drop-on-demand inkjet printing. This approach allows us to unravel a clear correlation between deposition density and passivation outcome. We demonstrate that the passivation mechanism is critically governed by the deposition amount. At a low deposition density, both chemical and field-effect passivation are suboptimal. An optimal deposition density yields the most effective synergy, maximizing defect suppression while maintaining a strong field-effect passivation. However, excessive deposition leads to disordered molecular packing, which diminishes the field effect, induces energy-level misalignment, and increases series resistance. Consequently, the optimally passivated device delivers a champion power conversion efficiency (PCE) of 26.1% while demonstrating outstanding stability during operation. Our study highlights the indispensability of quantitative deposition for controlling passivation mechanisms, providing a fundamental insight and a scalable pathway toward highly efficient and stable perovskite photovoltaics.