Efficient Perovskite Solar Cells with Negligible Hysteresis Enabled by Solution-Processed Spinel Nickel Cobalt Oxide as Hole Transport Layer
The current-voltage hysteresis is a critical issue to determine the photovoltaic performance for perovskite solar cells, and thus it is imperative to develop high efficiency perovskite solar cells without hysteresis behavior. We here report fabrication of efficient planar heterojunction perovskite solar cells employing the solution processed NiCo2O4 as hole transport layer. Spinel NiCo2O4 thin film from sol-gel process exhibits high optical transparency, well-matched energy bands, smooth film morphology and decent electrical conductivity, much better than NiO, a typical hole transport layer for perovskite solar cells. We herein demonstrate that excellency in hole extraction, transport and collection properties are for the solution-processed NiCo2O4 achieves device efficiency up to 18.16% for the planar heterojunction perovskite solar cells. More importantly, the devices with NiCo2O4 exhibits hysteresis-free behavior regardless of voltage scan rate, which outperforms NiO-based devices.