Plasma-assisted atomic layer deposition of nickel oxide as hole transport layer for hybrid perovskite solar cells

Abstract

Careful interface design and engineering are “keys” to effectively implement a conformal 10 nm plasma-assisted atomic-layer-deposited NiO film as hole transport layer in a p–i–n perovskite solar cell architecture.

Robust Inorganic Hole Transport Materials for Organic and Perovskite Solar Cells: Insights into Materials Electronic Properties and Device Performance

“…[114,115] Electrodeposition, [116,117] chemical bath deposition, [118] and spray coating [119] are alternative solution-based techniques demonstrated, suitable to obtaining good performing NiO. High-performing devices have been demonstrated, also using NiO from physical methods: pulsed laser deposition, [120] e-beam deposition, [121] glancing angle deposition, [122] atomic layer deposition (ALD), [123,124] sputtering, [125,126] or even the evaporation of metallic nickel followed by oxidation in air at high temperatures. [127] The high conductivity of selective contacts is fundamental to minimize the resistive losses detrimental to the energy output of PV devices.…”

Atomic scale surface modification of TiO2 3D nano-arrays: plasma enhanced atomic layer deposition of NiO for photocatalysis

“…A report by Koushik et al noted similar thermal behaviour for a Ni(MeCP) 2 PEALD process and suggested the behaviour was a consequence of a change in density. 9 To affirm this, film density between 75-325 • C was investigated by XRR. XRR measurements determined that between 75-200 • C the film density increased from 5.1-6.2g cm −3 and reduced to 5.8g cm −3 at 325 • C. It is therefore likely that the film growth rate reduces as a function of temperature due to a densification of the films.…”

“…, with oxygen plasmas respectively. 9,[20][21][22] These studies have demonstrated that conformal growth of NiO is possible with cyclopentadienyl based nickel precursors and O 2 plasma. Given the low cost of nickelocene (Ni(Cp) 2 ), it should be an attractive precursor for ALD.…”

“…NiO can be used as a hole collecting layer in photo junctions and have been shown to significantly improve the photocatalytic activity of materials such as perovskites. [8][9][10] NiO, alternatively when utilised as co-catalytic layer on TiO 2 photoandoes, NiO has been shown to reduce the onset potential and increase photoconversion efficiency. 11 It has been proposed the improvement of the photoanodes is a result of the formation of a P-N junction which increases charge separation and increase carrier lifetimes of TiO 2 .…”

Nickel oxide thin films grown by chemical deposition techniques: Potential and challenges in next‐generation rigid and flexible device applications

“…They also estimated a very low hole mobility (10 −5 ‐10 −3 cm 2 V −1 second −1 ) 80 . High carrier concentrations, 10 19 to 10 20 cm −3 , by Mott‐Schottky analysis have also been reported for as‐deposited films grown using aminoalkoxide and cyclopentadienyl precursors 81 . Mott‐Schottky analysis was also used to estimate the work function by flat band potential and valence band position (E VB ) of the ALD NiO x .…”