Yttrium-Doped Zinc Oxide (Zn_1–xY_xO) Electron Transport Layers: A Pathway to Enhanced Efficiency in PbS Colloidal Quantum Dot Solar Cells

Significant progress has been achieved in PbS colloidal quantum dot solar cells (CQDSCs) by concentrating on structural engineering, band-alignment engineering, and enhancing the interfacial functionality of colloidal quantum dots (CQDs). Nonetheless, designing a durable and efficient photovoltaic device still represents a considerable obstacle for scientists in this domain. The present work demonstrates that the photovoltaic performance of PbS CQDSCs can be increased by adding 1-5 wt % yttrium into the zinc oxide (YZO) ETL. ZnO and YZO thin films are prepared under mild annealing conditions, while the PbS CQDs absorber layer is applied using a one-step deposition process. The results indicate that 3 wt % yttrium doping (YZO-2) can significantly raise the conduction band edge and optical transmission while concurrently minimizing the density of oxygen defects and the surface roughness in comparison to alternative ETLs. Consequently, PbS CQDSCs utilizing YZO-2 ETL show the optimal power conversion efficiency (PCE) of 14.92%, surpassing the 14.20% PCE of ZnO-based PbS CQDSCs by 5.1%. Similarly, PbS CQDSCs incorporating the YZO-2 ETL demonstrate long-term durability of around 75 days. Moreover, Y-doping in ZnO presents a feasible method for economical, high-efficiency CQDSCs.