Preparation of Nickel Oxide Nanoflakes for Carrier Extraction and Transport in Perovskite Solar Cells

Abstract

Hole transport layers (HTLs) with high conductivity, charge extraction ability, and carrier transport capability are highly important for fabricating perovskite solar cells (PSCs) with high power conversion efficiency and device stability. Low interfacial recombination between the HTL and perovskite absorber is also crucial to the device performance of PSCs. In this work, we developed a three-stage method to prepare NiOx nanoflakes as the HTL in the inverted PSCs. Due to the addition of the nanoflake layer, the deposited perovskite films with larger grain sizes and fewer boundaries were obtained, implying higher photogenerated current and fill factors in our PSCs. Meanwhile, the downshifted valence band of the NiOx HTL improved hole extraction from the perovskite absorber and open-circuit voltages of PSCs. The optimized device based on the NiOx nanoflakes showed the highest efficiency of 14.21% and a small hysteresis, which outperformed the NiOx thin film as the HTL. Furthermore, the device maintained 83% of its initial efficiency after 60 days of storage. Our results suggest that NiOx nanoflakes provide great potential for constructing PSCs with high efficiency and long-term stability.

On the properties of ZnO nanorods (ZnO NRs)/NiO heterostructure prepared by double chemical bath deposition

“…It is often acknowledged that growth rate impacts 2-D network nanoflake array formation. A very slow growth rate is expected to significantly influence 2-D network nanoflake array formation and orientation [33,35]. Following this observation and argument, it is possible to conclude that our approach is associated with a fast growth rate, which favours the 2-D network nanoflake array formation and orientation.…”

Interfacial modification between NiOx and perovskite layers with hexafluorophosphate salts for enhancing device efficiency and stability of perovskite solar cells

“…The details for the preparation and deposition of the perovskite and PCBM + TBABF 4 layers were referred to our previous report. 25 Afterward, 0.1 mol% PEI in anhydrous IPA was spin-coated onto the PCBM layer at 4500 rpm for 30 s. Finally, 100 nm-thick Ag electrodes were thermally evaporated under a base pressure of 8 × 10 −6 torr. The active area of each device is 4.5 mm 2 .…”

Solution-Processed Metal Oxide Nanostructures for Carrier Transport

“…The optimized PSC exhibited an open-circuit voltage (V OC ) of 1.11 V, a short-circuit current density (J SC ) of 22.9 mA/cm 2 , a fill factor (FF) of 0.65, and a power conversion efficiency (PCE) of 16.6% with oxygen plasma treatment of the SnO 2 nanostructures prior to the deposition of the perovskite absorbing layer. Chang et al developed a three-stage method to prepare NiO x nanoflakes [4]. The three-stage method is as follows: (1) formation of ZnO nanorods by a hydrothermal synthesis, (2) chemical bath deposition of mesoporous NiO x on ZnO nanorods, and (3) ZnO removal by chemical etching.…”