Enhancing NiOx Hole Transport Properties through Planarity Modulation of Organic Small Molecules for Inverted Perovskite Solar Cells

• • The NiOx/1,5-NOT-based device achieves a power conversion efficiency (PCE) of 24.20%, surpassing the NiOx control (18.12%) and 2,6-NOT-based (21.87%) devices, demonstrating a relative improvement of 33.5% over the control. • • The molecular planarity modulation via 1,5-NOT enhances hole extraction and transport capabilities and increases the conductivity of NiOx, directly addressing the bottleneck of low intrinsic conductivity in NiOx. • • The 1,5-NOT modification leads to excellent long-term stability, attributed to reduced interfacial defects and suppressed charge recombination, which is critical for commercial viability. • • The study provides a new strategy for NiOx modification using small organic molecules, with the planarity of the modifier being a key design parameter for optimizing hole transport in inverted PSCs.