Hexagonal mesoporous silica islands to enhance photovoltaic performance of planar junction perovskite solar cells

The efficiency of perovskite solar cells based on mesoscopic TiO2 was soaring over the past 3 years and is expected to reach over 25​% by engineering the compn. 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 1st time, the authors use the wormhole-​like hexagonal mesoporous SiO2 (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, the authors realized an av. PCE of 17.6​% over 30 devices, which is higher than that of the controlled intrinsic planar heterojunction device (15.85​%)​.