Performance of Air-Stable Cs_2SnI_6 Perovskite as Electron Transport Layer in Inverted Bulk Heterojunction Solar Cell

摘要

In recent years, perovskite material has been extensively studied due to its unique physical properties and promising application in the third generation of solar cells. In particular, Sn-based perovskite has been considered to replace Pb-based perovskite because of the toxic effects and it can lead to other serious problems related to the environment. Cs_2SnI_6 perovskite has been known to be synthesized in a simple chemical process and it can be produced on a large scale. Moreover, this material is also oxygen and moisture stable due to the high oxidation state of tin. In this study, we synthesize air-stable Cs_2SnI_6 perovskite by the use of the wet chemical process at room temperature. Next, we attempt to fabricate the inverted bulk heterojunction solar cells incorporated Cs_2SnI_6 as electron transport layer in the configuration of ITO/ZnO/Cs_2SnI_6/P3HT:PCBM/PEDOT:PSS/Ag to improve device performance. The Cs_2SnI_6 perovskite shows an Fm-3m space group with a cubic lattice parameter of 11.62? confirmed by X-Ray Diffraction (XRD) measurement, while UV-Vis measurement indicates this type of perovskite has direct band gap ~3.1 eV. The fabricated solar cell device reveals the enhancement in current density at short circuit condition (Jsc) from 64.69 mA/cm~2 to 77.02 mA/cm~2 with the addition of 2.25 mg/ml Cs_2SnI_6 along with the enhancement of power conversion efficiency (PCE) from 7.05% to 9.75% as characterized by J-V measurement. In our case, the voltage at open circuit condition (Voc) of the device does not perform significant improvement. Besides, it is found that the solar cell devices are quite stable even after exposure in the air for six weeks after fabrication, as indicated by PCE performance.