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 (fO2) 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.

Effects of substrate bias on the sputtering of high density (111)-nanotwinned Cu films on SiC chips.

This article presents a study of the influence of the substrate bias on the microstructure, preferred orientation, and mechanical and electrical properties of nanotwinned Cu film. The formation of a nanotwinned structure and (111) surface orientation can be properly controlled by applied substrate bias. High density nanotwinned structures were introduced into Cu films sputtered on SiC substrates with over 90% of (111)-orientation at - 150 V. Densely packed Cu nanotwins were observed within the columnar grains stacked up on each other along the film growth direction, with an average twin spacing of 19.4 nm. The Cu films deposited on SiC substrate via bias sputtering had surface roughness of 8.6 to 15.8 nm. The resistivity of the copper nanotwinned films sputtered with various substrate biases varied. The optimal indentation, 2.3 GPa, was found in the nanotwinned Cu film sputtered with a bias voltage of - 150 V. The effects of Ar ion bombardment on microstructure, surface morphology and properties are further discussed.