Highly Stable and Enhanced Performance of p-i-n Perovskite Solar Cells via Cuprous Oxide Hole-Transport Layers

Solar light is a renewable source of energy that can be used and transformed into electricity using clean energy technology. In this study, we used direct current magnetron sputtering (DCMS) to sputter p-type cuprous oxide (Cu₂O) films with different oxygen flow rates (f_O2) as hole-transport layers (HTLs) for perovskite solar cells (PSCs). The PSC device with the structure of ITO/Cu₂O/perovskite/[6,6]-phenyl-C₆₁-butyric acid methyl ester (PC₆₁BM)/bathocuproine (BCP)/Ag showed a power conversion efficiency (PCE) of 7.91%. Subsequently, a high-power impulse magnetron sputtering (HiPIMS) Cu₂O film was embedded and promoted the device performance to 10.29%. As HiPIMS has a high ionization rate, it can create higher density films with low surface roughness, which passivates surface/interface defects and reduces the leakage current of PSCs. We further applied the superimposed high-power impulse magnetron sputtering (superimposed HiPIMS) derived Cu₂O as the HTL, and we observed PCEs of 15.20% under one sun (AM1.5G, 1000 Wm^-2) and 25.09% under indoor illumination (TL-84, 1000 lux). In addition, this PSC device outperformed by demonstrating remarkable long-term stability via retaining 97.6% (dark, Ar) of its performance for over 2000 h.