Modification of electron-transport layers with mixed RGO/C60 additive to boost the performance and stability of perovskite solar cells: A comparative study

In perovskite solar cells (PSCs), the transportation of photogenerated electrons can be controlled by the modification of electron-transport layers. In the present study, TiO2 doped with reduced graphene oxide (RGO) and C60 was used as an electron-transport layer in hole-transport-free porous perovskite solar cells. The PSCs were fabricated in the laboratory by a single-step method. As the measurements showed, the use of a mixed electrontransport layer in perovskite cells helps to decrease the absorption in perovskite layers in the visible range, while the electron transport is increased. The scanning electron microscopy images and the X-ray diffraction patterns also showed that large perovskite crystals have fewer holes and better morphology than the reference cells fabricated with pure mesoporous TiO2. Appropriate amounts of RGO and C60 were used to compare the parameters of the modified fabricated cells with those of the reference cells. Moreover, the stability of the fabricated cells was examined by the comparison of them to the reference cells. This comparative study showed an increase of efficiency from 5.15% to 9.10% for the untreated and the treated samples respectively. Less cell destruction was also observed over a 32-day period for the treated samples, indicating the improvement of the shelf stability of PSCs through the suggested ETL modification.