Outstanding Photocurrent Density and Incident Photon‐to‐Current Conversion Efficiency of Liquid‐State NiO Perovskite‐Sensitized Solar Cells

The efficiency and photocurrent density reported for p‐type‐sensitized solar cells up to now are still lagging behind that of the n‐type counterparts, limiting the successful development of p–n tandem cells. To circumvent this issue, NiO thin film is fabricated by the aerosol‐assisted chemical vapor deposition (AACVD) technique and used in p‐type solar cells. A systematic study is conducted to comprehend the correlation between NiO thickness and the power conversion efficiency (PCE) of liquid‐state NiO‐based sensitized solar cells. By carefully designing the cell components, this type of device demonstrates the highest photocurrent density (Jsc) exceeding 18 mA cm−2 when using iodine/triiodide as the redox shuttle matching the one produced by the TiO2 counterpart. This is accomplished by 1) using the AACVD technique for the one‐step deposition of compact and mesoporous NiO electrodes, 2) optimizing the thickness of the NiO layer through controlling the deposition time, and 3) adopting methylammonium lead iodide (CH3NH3PbI3) as a light harvester prepared via a sequential deposition method. Compact and mesoporous films based on NiO are simultaneously prepared via the single‐step aerosol‐assisted chemical vapor deposition. The use of NiO with an appropriate film thickness as the photocathode in liquid‐state perovskite‐sensitized solar cells leads to a remarkably high photocurrent density (JSC). The outstanding JSC is benefited from the impressive incident photon‐to‐current conversion efficiency.