Abstract
The efficiency of perovskite solar cells based on mesoscopic TiO
2
has been soaring over the past three years and is expected to reach over 25% by engineering the composition of perovskite and interface layers. Efforts to increase the power conversion efficiency (PCE) of planar junction perovskite solar cells have been made from different perspectives. For the first time, we use the wormhole-like hexagonal mesoporous silica (HMS) to modify the substrate surface inside the planar junction perovskite solar cell to improve efficiency. The formed random islands of HMS decreased the loading of the perovskite layer, leading to abnormal growth of perovskite and increased light path length. Using HMS islands in a planar heterojunction device, we realized an average PCE of 17.6% over 30 devices, which is higher than that of the controlled intrinsic planar heterojunction device (15.85%).