Efficient and stable hole-conductor-free mesoscopic perovskite solar cells using SiO2 as blocking layer

Efficient and stable hole-conductor-free mesoscopic perovskite solar cells were fabricated using SiO2 as blocking layer which was inserted between the top carbon electrode and bottom electron-transport-layer in the device. Power conversion efficiency of 13.09% (AM1.5G, 100 mW/cm(2)) was obtained, which was comparable to those using ZrO2 as the blocking layer. Besides that, prolonged stability has been obtained. After being stored at ambient air for 104 days (relative humidity between 50% and 70%), 94.19% of the starting efficiency was preserved for devices without any encapsulation. Moreover, effect of thickness of SiO2 blocking layer on device performance was studied by tuning the concentration of SiO2 paste. A moderate concentrate was found to be beneficial to device performance. Without blocking layer, poor performance was observed due to short cutting between top electrode and bottom electron-transport-layer; when concentration of SiO2 paste is relative higher (which corresponded to relatively thicker films), cracks appeared which caused short-cuffing. Finally, due to the relative higher preservation of Si element (more than 1000 times of Zr) in earth, applying SiO2 as blocking layer could further lower down the cost of the carbon based hole-conductor-free mesoscopic perovskite solar cells.