Dual-sided interface engineering via aluminum glycinate for efficient and stable P-I-N PbS quantum dot solar cells

Lead sulfide (PbS) colloidal quantum dots (CQDs) offer exceptional promise for next-generation low-cost photovoltaics with tandem architectures, owing to their superior light-harvesting capabilities in the short-wave infrared (SWIR) region. However, interfacial mismatches in architectures limit their compatibility with current high-efficiency, solution-processed p-i-n tandem cells. To overcome these limitations, we introduce an interfacial engineering strategy between hole transport layer (HTL) and PbS CQDs layer by using a multifunctional organometallic linker aluminum glycinate (AG). Spectroscopic analysis reveals a dual interfacial modification mechanism, wherein aluminum centers in AG coordinate with residual phosphonic acids on HTL to minimize chemical disorder, while amino and carboxyl groups synergistically heal undercoordinated Pb surface defects. This strategy establishes a chemically robust transition layer that significantly suppresses non-radiative recombination. Consequently, the power conversion efficiency (PCE) increases substantially from 12.78% to 14.12%, representing one of the highest reported efficiencies for p-i-n PbS CQD solar cells to date. This work offers a straightforward chemical modulation pathway to overcome interfacial carrier losses, advancing PbS CQDs toward practical deployment in next-generation infrared and tandem photovoltaics.