Super-hydrophilic substrate for blade-coated Dion-Jacobson perovskite solar cells with efficiency exceeding 19%

Employing super-hydrophilic substrates is a feasible approach to suppress pinholes and buried voids in perovskite films statistically over large areas. However, substrates terminating with organic functional groups are usually not super-hydrophilic. Herein, constructing surface nanostructures with NiOx nanoparticles is proposed as a universal strategy to transform ordinary hydrophilic organic hole transport layers (HTLs) into super-hydrophilic HTLs. In addition, coating organic layers on NiOx can passivate the surface defects of NiOx nanoparticles. Based on this strategy, pinhole- and void-free Dion–Jacobson-type quasi-two-dimensional (Q-2D) perovskite (BDA)MA4Pb5I16 films have been blade-coated on NiOx/MeO-2PACz substrates. Perovskite solar cells with inverted structure show a remarkable power conversion efficiency of 19.52% and a low non-radiative open-circuit voltage loss of 0.12 V, proving the vital role of substrate wettability on device efficiencies.