Luo Yuan, Li Sihan, Xia Rui, Wang Xianzhao, Shi Biao, Han Wei, Liu Pengfei, Xu Ye, Zhang Xueling, Chen Yifeng, Gao Jifan, Xia Shuangbiao, Wang Yutao, Zhang Liping, Wang Pengyang, Zhao Ying, Zhang Xiaodan
Institute of Photoelectronic Thin Film Devices and Technology, Renewable Energy Conversion and Storage Center, State Key Laboratory of Photovoltaic Materials and Cells, Nankai University, Tianjin, 300350, P. R. China.
Tianjin Key Laboratory of Efficient Utilization of Solar Energy, Tianjin, 300350, P. R. China.
Small. 2025 Aug 19:e06247. doi: 10.1002/smll.202506247.
Sputtered nickel oxide (NiO) is a promising material for hole transport layers (HTLs) in industrializing perovskite solar cells (PSCs) due to its scalable and conformal growth. However, its low conductivity and interfacial instability limit device performance. Herein, high-quality undoped NiO (DC-N) HTLs are developed fabricated via direct current (DC) reactive sputtering (Ni target) coupled with low-temperature (≤ 200 °C) air annealing. By synergistically modulating process conditions, nickel vacancy density is tailoreded to balance photoelectric properties and interfacial stability of DC-N HTLs, while elucidating trade-offs among conductivity, transmittance, and interfacial stability. Contrastive analysis reveals that the DC-N HTLs outperform conventional RF-sputtered NiO HTLs (derived from ceramic targets, doped or undoped), mainly attributed to their outstanding conductivity, an ideal Ni/Ni ratio, good crystallization, and excellent interface properties, which mitigate parasitic absorption, recombination losses, and charge transport losses. By employing DC-N HTLs, inverted PSCs with a 1.68 eV bandgap achieve a power conversion efficiency (PCE) of 20.71%, increasing to 22.45% with Me-4PACz/AlO interlayers and thick-film perovskite. Notably, integrating DC-N HTLs into textured perovskite/silicon tandem solar cells delivered a PCE of 32.02% (1.0 cm aperture area), providing valuable insights for NiO-based tandem photovoltaics.
