Electrochemical deposition of NiO bunsenite nanostructures with different morphologies as the hole transport layer in polymer solar cells

Hole transport layers (HTLs) are one of the most important components of bulk heterojunction polymer solar cells (BHJ PSCs), having functions of optimizing interface, adjusting the energy match, and helping obtain higher PCE. Inorganic p-type semiconductors are alternative HTLs due to their chemical stability, high mobil- ity, high transparency, and applicable valence band (VB) energy level. In this work, interlayer engineering in BHJ PSC was performed using solution-processed p-type nickel oxide (NiO) as the HTL. NiO nanostructures were synthesized by anodic potentiostatic and cyclic voltammetry (CV) electrodeposition methods. Simple adjustment of the applied potential regime and electrodeposition parameters led to considerable structural and electrochemical changes in the resulting NiO. Eventually, the best sample was selected in terms of suitable surface conductivity, high optical transparency, and appropriate energy levels. NiO nanostructures with FCC crystal structure synthesized by anodic potentiostatic electrodeposition showed conductivity of 0.038 mS. cm-1 and charge mobility of 2.01 cm2.V-1s-1, respectively, about 30.2 % and 24.8 % higher than the NiO syn- thesized by CV. The anodic potentiostatic electrodeposition method increased the photovoltaic performance of the PSCs by 43 % compared to the CV method. The average power conversion efficiencies for the anodic poten- tiostatic and CV methods were 2.95 % and 4.21 %, respectively. The PCE of these cells was about 13 % and 62 % higher than that considered for the reference device prepared based on the PEDOT:PSS HTL.

Automated summary

In this work, solution-processed p-type nickel oxide (NiO) was used as the hole transport layer (HTL) in bulk heterojunction polymer solar cells (BHJ PSCs). Interlayer engineering of BHJ PSC was achieved by adjusting the potential regime and electrodeposition parameters. The resulting NiO nanostructures showed improved structural and electrochemical properties. The anodic potentiostatic electrodeposition method increased the photovoltaic performance of the PSCs compared to the cyclic voltammetry (CV) method.