Nickel oxide (NiO x) has received widespread attention as a promising hole transport layer (HTL ) in organic solar cells (OSCs), which poses stability challenges due to acidic and hygroscopic properties of traditional HTL and PEDOT :PSS. Potential solutions are provided. However, NiOx has a lower work function (WF) relative to the donor polymer, thereby reducing the charge injection efficiency in OSC s.
Li Weiwei and Qiaomei Chen of Beijing University of Chemical Technology customized NiOx nanoparticles through rare earth doping to optimize WF and explore the impact of ion radius on their electronic properties. Lanthanum (La3+) and yttrium (Y3+) ions with larger ionic radii can effectively dope 1% and 3% respectively, while scandium (Sc3+) with smaller ionic radius can achieve enhanced doping of 5%. A higher doping ratio significantly increases the WF of NiOx. 5% Sc3+ doping increases the WF of pure NiOx from 4.77 eV to 4.99 eV while maintaining high conductivity.
Therefore, using 5% Sc-doped NiOx as HTL increases the power conversion efficiency (PCE
) of OSC to 17.13%, which exceeds 15.64% of pure NiOx. By introducing the reducing agent catechol, the efficiency is further increased to 18.42%, which is better than the device based on PEDOT:PSS. Furthermore, when used in the ternary blend system (D18:N3:F-BTA3), PCE achieved a high efficiency of 19.18%, which is the best performance among the reported OSCs using solution-processed inorganic nanoparticles.
Zhang, G., Chen, Q., Zhang, Z., Gao, Z., Xiao, C., Wei, Y., Li, W., NiOx Nanoparticles Hole-Transporting Layer Regulated by Ionic Radius-Controlled Doping and Reductive Agent for Organic Solar Cells with Efficiency of 19.18%. Adv. Mater. 2023, 2310630.
https://doi.org/10.1002/adma.202310630