Merging Passivation in Synthesis Enabling the Lowest Open-Circuit Voltage Loss for PbS Quantum Dot Solar Cells.

The high open-circuit voltage (V oc ) loss arising from insufficient surface passivation is the main factor that limits the efficiency of current PbS colloidal quantum dots (CQDs) solar cell. Here, we perform synergistic passivation in the direct synthesis of conductive PbS CQD inks by introducing multifunctional ligands to well coordinate the complicated CQDs surface with the thermodynamically optimal configuration. The improved passivation effect is intactly delivered to the final photovoltaic device, leading to an order lower surface trap density and beneficial doping behavior compared to the control sample. The obtained CQD inks show the highest PLQY of 24% for all photovoltaic PbS CQD inks, which is more than twice the reported average PLQY value of ཞ10%. As a result, a high V oc of 0.71 V and PCE of 13.3% is achieved, which results in the lowest V oc loss (0.35 eV) for the reported PbS CQD solar cells with PCE >10%, comparable to that of perovskite solar cells. Our work provides valuable insights into the future CQDs passivation strategies and also demonstrates the great potential for the direct-synthesis protocol of PbS CQDs. This article is protected by copyright. All rights reserved.