Overcoming the Limitations of Sputtered Nickel Oxide for High‐Efficiency and Large‐Area Perovskite Solar Cells

Abstract

Perovskite solar cells (PSCs) are one of the promising photovoltaic technologies for solar electricity generation. NiOx is an inorganic p‐type semiconductor widely used to address the stability issue of PSCs. Although high efficiency is obtained for the devices employing NiOx as the hole transport layer, the fabrication methods have yet to be demonstrated for industrially relevant manufacturing of large‐area and high‐performance devices. Here, it is shown that these requirements can be satisfied by using the magnetron sputtering, which is well established in the industry. The limitations of low fill factor and short‐circuit current commonly observed in sputtered NiOx‐derived PSCs can be overcome through magnesium doping and low oxygen partial pressure deposition. The fabricated PSCs show a high power conversion efficiency of up to 18.5%, along with negligible hysteresis, improved ambient stability, and high reproducibility. In addition, good uniformity is also demonstrated over an area of 100 cm2. The simple and well‐established approach constitutes a reliable and scale method paving the way for the commercialization of PSCs.

Electron‐Beam‐Evaporated Nickel Oxide Hole Transport Layers for Perovskite‐Based Photovoltaics

“…[46][47][48]50] As shown in Figure 1, this problem is avoided in this work by using oxygen as process gas. [46][47][48]50] As shown in Figure 1, this problem is avoided in this work by using oxygen as process gas.…”

“…The variations between the samples are comparatively low as the homogeneous substrate material obtained from the electron beam evaporation is a dominating factor for a homogenous absorber crystallization and, thus improved reproducibility. [36,37,41,47] Fortunately, this might relativize the importance of doping and significantly simplify the fabrication process of high-quality NiO x layers, as additional doping of the layer adds further parameters to the process making a deposition more complex and expensive. Except of the all-evaporated devices, these values are slightly lower than the values of the backward scan, indicating a small hysteresis between backward and forward scans.…”

“…[33,34] To tackle all these problems, novel materials for charge extracting layers-in particular, HTLs-are required. [45,47] By doing so, stable PCEs up to 18.5% were achieved, being the highest value for a vacuum-processed NiO x layer currently. One of the most studied materials in the literature is nickel oxide (NiO, as well as NiO x nonstoichiometric phases).…”

“…In a tandem solar cell, the strong parasitic absorption in spiro-MeOTAD used in the top solar cell can cause significant current losses, thus motivating the search for alternative materials to achieve the highest possible PCEs. [45][46][47][48][49] The most striking benefit of sputtering is the ease of additional doping (e.g., with Co, Cu, or Mg) to improve the conductivity of the NiO x layer. Inorganic HTL materials are among the most promising materials on the route toward highly stable and inexpensive perovskite solar cells for single-junction as well as multi-junction devices.…”

“…Inorganic HTL materials are among the most promising materials on the route toward highly stable and inexpensive perovskite solar cells for single-junction as well as multi-junction devices. [47] Besides sputtering, electron beam evaporation of metal oxides is another common technique for optical coatings. [35] As a metal oxide, it promises low material costs and good intrinsic chemical stability.…”