NiN-Passivated NiO Hole-Transport Layer Improves Halide Perovskite-Based Solar Cell

Abstract

The interfaces between inorganic selective contacts and halide perovskites (HaPs) are possibly the greatest challenge for making stable and reproducible solar cells with these materials. NiO x , an attractive hole-transport layer as it fits the electronic structure of HaPs, is highly stable and can be produced at a low cost. Furthermore, NiO x can be fabricated via scalable and controlled physical deposition methods such as RF sputtering to facilitate the quest for scalable, solvent-free, vacuum-deposited HaP-based solar cells (PSCs). However, the interface between NiO x and HaPs is still not well-controlled, which leads at times to a lack of stability and V oc losses. Here, we use RF sputtering to fabricate NiO x and then cover it with a Ni y N layer without breaking vacuum. The Ni y N layer protects NiO x doubly during PSC production. Firstly, the Ni y N layer protects NiO x from Ni 3+ species being reduced to Ni 2+ by Ar plasma, thus maintaining NiO x conductivity. Secondly, it passivates the interface between NiO x and the HaPs, retaining PSC stability over time. This double effect improves PSC efficiency from an average of 16.5% with a 17.4% record cell to a 19% average with a 19.8% record cell and increases the device stability.

Evaporated Nickel Oxide Films with Slow Annealing and Interface Modification for Perovskite Solar Cells

“…Through optimizing interface contact, reducing interface defect density, and significantly enhancing the quality of PVK deposition, more efficient charge extraction is achieved. ,, In recent years, a novel metal nitride (such as Ni y N x and Zn y N x ) interface modifier has been introduced for the modification of NiO x . Leveraging the excellent characteristics of such substances, it has successfully enhanced the performance of NiO x material in PSCs. − Therefore, the optimization of NiO x itself and its surface is absolutely necessary.…”

Film Thickness Effect in Restructuring NiO into LiNiO2 Anode for Highly Stable Lithium-Ion Batteries

“…After 600 cycles, this anode material delivered a high capacity of ~1900 mAh g −1 , which is much higher than the theoretical capacity of ~1000 mAh g −1 . The NiO nanostructure also received great attention for its various electrical/optical applications, including capacitors, gas sensors, solar cells, and magnetic applications [36][37][38][39][40]. NiO has a theoretical capacity of ~720 mAh g −1 , which is more than twice that of graphene [41].…”

Understanding and Mitigating the Degradation of Perovskite Solar Cells Based on a Nickel Oxide Hole Transport Material during Damp Heat Testing

“…NiO x can also be doped to improve hole conductivity, notably with different cations such as Li, 28,29 Mg, 30,31 Al, 32 Cs, 33,34 Cu, 35,36 and Na 2 S 37 or with N 2 gas during the sputtering of a Ni target to form a Ni y N layer. 38 Promising stability results have been demonstrated when exposing cells with spin-coated NiO x nanoparticles to various stresses (thermal, 39−41 damp heat, 41,42 light soaking, 39,42 and temperature cycling). 41,43 Further reports show thermal and light-soaking stability for cells with NiO x deposited by atomic layer deposition 44 and sputtering.…”

“…Overall, NiO x is an attractive material for hole extraction in solar cells as it is naturally p -type doped (oxygen-rich) − and it has a suitable valence band alignment with typical lead iodide perovskite absorbers, as well as a high conduction band offset with the perovskite conduction band (bandgap ∼3.6 eV), thus ensuring charge carrier selectivity. NiO x can also be doped to improve hole conductivity, notably with different cations such as Li, , Mg, , Al, Cs, , Cu, , and Na 2 S or with N 2 gas during the sputtering of a Ni target to form a Ni y N layer …”