The ligand exchange procedure of CsPbI3 perovskite quantum dots (PQDs) enables the fabrication of thick and conductive PQD solids that act as a photovoltaic absorber for solution‐processed thin‐film solar cells. However, the ligand‐exchanged CsPbI3 PQD solids suffer from deterioration in photovoltaic performance and ambient stability due to the surface traps, such as uncoordinated Pb2+ sites on the PQD surface, which are generated after the conventional ligand exchange process using ionic short‐chain ligands dissolved in polar solvents. Herein, a facile surface stabilization is demonstrated that can simultaneously improve the photovoltaic performance and ambient stability of CsPbI3 PQD photovoltaic absorber using covalent short‐chain triphenylphosphine oxide (TPPO) ligands dissolved in a nonpolar solvent. It is found that the TPPO ligand can be covalently bound to uncoordinated Pb2+ sites and the nonpolar solvent octane can completely preserve the PQD surface components. Owing to their synergetic effects, the CsPbI3 PQD photovoltaic absorber stabilized using the TPPO ligand solution dissolved in octane exhibit higher optoelectrical properties and ambient stability than the control absorber. Consequently, CsPbI3 PQD solar cells composed of PQD photovoltaic absorbers fabricated via surface stabilization strategy provide an improved power conversion efficiency of 15.4% and an enhanced device stability.

The hole transport layer (HTL) plays a key role in inverted perovskite solar cells (PSCs), and nickel oxide has been widely adopted for HTL. However, a conventional solution‐processed bottom‐up approach for NiOx (S‐NiO) HTL fabrication shows several drawbacks, such as poor coverage, irregular film thickness, numerous defect sites, and inefficient hole extraction from the perovskite layer. To address these issues, herein, a novel NiOx HTL top‐down synthesis route via electrochemical anodization is developed. The basicity of the electrolyte used in anodization considerably influences electrochemical reactions and results in the structure of the anodized NiOx (A‐NiO). The optimized A‐NiO provides outstanding optoelectrical properties, including uniform film thickness, enhanced transmittance, deep‐lying valance band, low trap density, and better hole extraction ability from the perovskite. Owing to these advantages, the A‐NiO‐based inverted PSC exhibits an improved power conversion efficiency of 21.9% compared with 19.1% for the S‐NiO‐based device. In addition, the A‐NiO device shows a higher inlet and long‐term ambient stability than the S‐NiO device due to the superior hole transfer ability of A‐NiO, which suppresses charge accumulation between NiOx and the perovskite interface.