Critical Role of Removing Impurities in Nickel Oxide on High‐Efficiency and Long‐Term Stability of Inverted Perovskite Solar Cells

Abstract

The performance enhancement of inverted perovskite solar cells applying nickel oxide (NiOx) as the hole transport layer (HTL) has been limited by impurity ions (such as nitrate ions). Herein, we have proposed a strategy to obtain high‐quality NiOx nanoparticles via an ionic liquid‐assisted synthesis method (NiOx‐IL). Experimental and theoretical results illustrate that the cation of the ionic liquid can inhibit the adsorption of impurity ions on nickel hydroxide through a strong hydrogen bond and low adsorption energy, thereby obtaining NiOx‐IL HTL with high conductivity and strong hole‐extraction ability. Importantly, the removal of impurity ions can effectively suppress the redox reaction between the NiOx film and the perovskite film, thus slowing down the deterioration of device performance. Consequently, the modified inverted device shows a striking efficiency exceeding 22.62 %, and superior stability maintaining 92 % efficiency at a maximum power point tracking under one sun illumination for 1000 h.

Overcome Low Intrinsic Conductivity of NiOx Through Triazinyl Modification for Highly Efficient and Stable Inverted Perovskite Solar Cells

“…The reverse (forward) scan and detailed parameters are recorded in Figure a and Table 1 , which is consistent with our previous report. [ 35 ] The Control device displays a relative low V OC of 1.11 (1.10) V, J SC of 22.53 (21.89) mA cm −2 and FF of 80.40% (79.47%), thence an unsatisfactory PCE of 20.12% (19.20%). On the contrary, an improved PCE of 22.81% (22.13%) is observed in NiO x :TTTS device with enhanced V OC 1.15 (1.14) V, J SC 23.49 (23.15) mA cm −2 and FF 84.68% (83.84%).…”

Crack‐Free Monolayer Graphene Interlayer for Improving Perovskite Crystallinity and Energy Level Alignment in Efficient Inverted Perovskite Solar Cells

“…The record PCE is over 22% of the MAPbI 3 -based inverted PSCs with NiO x HTL. [10][11][12] To date, the NiO x HTL in inverted PSC has been prepared by various methods, such as magnetron sputtering, electron beam deposition, pulsed laser deposition, and solution process. [13] Among them, the solution process to fabricate NiO x HTL has been considered a promising approach due to its simple fabrication, low cost, and high yield.…”

Elimination of light-induced degradation at the nickel oxide-perovskite heterojunction by aprotic sulfonium layers towards long-term operationally stable inverted perovskite solar cells

“…[10][11][12][13][14] On the other hand, recent studies revealed that the deprotonation and redox reactions between the organic iodide components in a perovskite absorber and Ni 3+ in the NiO x layer led to a relatively low device efficiency and stability. 12,15 Typically, Ni 3+ is a p-type dopant for improving the hole mobility of the NiO x films and could be easily generated by doping monovalent cations (such as Li + , Ag + , and Cs + ) or thermal annealing during the deposition processes, including spray-coating, atomic layer deposition, and sputtering. [16][17][18][19] To further improve the PSC performance, excess organic iodide salts were added into the perovskite layer to compensate for the loss of components near the NiO x contact, which enables the device efficiency approaching 20% and over a 500-hour operational lifetime.…”