Synergistic Effect between NiO_x and P3HT Enabling Efficient and Stable Hole Transport Pathways for Regular Perovskite Photovoltaics

Abstract As an inorganic hole transport material (HTM), nickel oxide (NiO_x) is widely used in perovskite solar cells (PSCs) due to its low cost and intrinsic stability. However, on account of its poor film formation on perovskite, the low power conversion efficiency (PCE) and stability of regular NiO_x‐based PSCs is a main obstacle for commercialization. Here, a solution‐processed inorganic/organic hybrid hole transporting system is developed to resolve this issue, thereby improving the PCE from 16.0% to 21.2%. Poly(3‐hexylthiophene) (P3HT) is studied as the typical case, revealing that the performance improvement mainly lies in the synergistic interaction between NiO_x and P3HT: 1) the introduction of P3HT improves assembly regularity and film uniformity of NiO_x; 2) electron redistribution between P3HT and NiO_x increases the Ni³⁺/Ni²⁺ ratio for higher hole mobility; 3) the feed‐back impact of NiO_x on P3HT enhances molecular orientation of polymer chains in P3HT for better hole transport through polymer framework. Finally, the encapsulated solar cell modules with P3HT‐promoted NiO_x maintains 91% of the initial efficiency after 1000 h aging at a harsh 85 °C/85% relative humidity condition. This finding provides a feasible approach for using NiO_x‐based HTMs to realize high‐performance regular PSCs, paving the way for their commercialization.