Effect of Carrier Transport in NiO on the Photovoltaic Properties of Lead Iodide Perovskite Solar Cells

Abstract

The effect of the NiO x thickness on the photovoltaic properties in planar type lead iodide perovskite solar cells consisted of Tin-doped indium oxide (ITO)/NiO x /Perovskite/Phenyl-C61-Butyric-Acid-Methyl Ester (PCBM)/Ag was investigated. For films ranging from 35 nm to 120 nm in the thickness, the NiO x thickness was found to be not crucial in fill factor and open circuit voltage. Calculations of the carrier flux in NiO x , estimated from Einstein-Smoluchowski relation and Fick's first law, found the carrier transport ability of the NiO x to fully compensate the photo-generated current density in perovskite layers and the theoretical current density ca. 26 mA cm −2 . The favorable physical properties such as mobility and thickness were also estimated for effective carrier transport in perovskite solar cells assuming that the carrier density is 10 15 cm −3.

Investigating the Growth of CH3NH3PbI3 Thin Films on RF‐Sputtered NiOx for Inverted Planar Perovskite Solar Cells: Effect of CH3NH3+ Halide Additives versus CH3NH3+ Halide Vapor Annealing

“…From Figure b and Figure S16 in the Supporting Information, it can be seen that the photovoltaic performance of the as‐prepared perovskite devices (without any treatment) showed lower efficiency ranging from ≈8% to 10% (best‐performing device showed 9.7% PCE). The obtained performance is consistent with the previous reports on sp‐NiO x ‐based perovskite (deposited by one‐step) solar cells . In case of MCVT, the device efficiency significantly improved, with minimum, average, and maximum PCE of 13%, 14.2%, and 15%, respectively (Figure b,d and Figure S16, Supporting Information).…”

“…On comparing the XRD and SEM results of perovskite film deposited on sputtered and solution processed NiO x , it can be inferred that sp‐NiO x under layer is affecting the crystallization of perovskite. For the present moment, the exact reason for the improper perovskite crystallization on sp‐NiO x and appearance of residual PbI 2 is unclear, however, we suspect that the presence of H 2 O, OH groups, and interstitial oxygen on the surface of NiO x or presence of Ni 3+ in NiO x decomposes MA + ions and generates MA + vacancies in the perovskite (during the annealing step) leading to the appearance of residual PbI 2 grains.…”

“…And, the sp‐NiO x HTL‐based PSCs show highly stable and operational output up to 4500 h . However, the performance of sp‐NiO x ‐based PSCs is not as high as solution processed ones . This low PCE of the sp‐NiO x is associated with greater loss in photovoltage and their open circuit voltage ( V oc ) is especially ≈100 mV lower than that of the solution processed NiO x ‐based PSCs .…”

“…Nickel oxide (NiO x ) is a promising hole transport layer (HTL) that is employed in PSCs compared to widely used spiro‐OMeTAD because of its high optical transparency, high stability, easy processability, and wide bandgap (crucial for aiding as effective electron blocking layer) . Vapor deposition of NiO x such as sputtering or evaporating is feasible for mass production and is one of the viable methods to deposit conformal pinhole‐free layer and the deposition parameters can be precisely controlled .…”

Nickel Oxide as Efficient Hole Transport Materials for Perovskite Solar Cells

“…The sputtered NiO x films usually exhibit a preferred orientation, which is closely related to the sputtering power and the substrate temperature. Fabrication of PSCs using sputtered NiO x films as the HTLs has been made, but the reported PCEs were usually quite low even high quality perovskite films were adopted, which was mainly attributed to the poor transmittance and conductivity of the sputtered NiO x films. In order to address this problem, dopants such as Li and Mg were introduced to the target.…”