High-efficiency perovskite solar cell using cobalt doped nickel oxide hole transport layer fabricated by NIR process

Lead halide perovskite solar cells (PVSCs) have potential toward commercialization because of their high efficiency and low cost. The hole transport layer (HTL) of p-i-n perovskite solar cell is usually made of NiOx. However, the NiOx needs to be processed at 300 degrees C for 15 min for good hole transport property. This long heating time prohibits the development of continuous commercial process. Thus, a rapid heating process for the NiOx film deposition is critical to realize the commercialization of PVSCs in the future. In this study, we develop a facile method to obtain high quality NiOx films annealed by NIR in a short time of 50 s. A short-wave NIR lamp at 2500 K was used to systematically investigate the effect of NIR intensity on the film quality of sol-gel NiOx. The PVSCs fabricated from NIR-annealed NiOx (NIR-NiOx) film show a comparable power conversion efficiency (PCE) to those fabricated from traditional hot-plate annealed-NiOx (HP-NiOx). In addition, the NIR annealed cobalt-doped NiOx (NIR-Co:NiOx) was synthesized to replace pristine NIR-NiOx. The PCE of PVSCs fabricated from this new NiOx film can be increased from 15.99% to 17.77%, which is due to the efficient hole extraction, less charge accumulation, and reducing V-oc loss resulting from the improved hole mobility, reduced interface resistance and well-matched work function. Our study paves a way to fulfill the requirements of low cost and low energy consumption of large scale production of high efficiency PVSCs.