ZnO quantum dots thin film for flexible perovskite solar cells

A new flexible perovskite solar cell is based on graphene (Gr) as the barrier layer and the atmospheric plasma jet (APjet)-treated ZnO quantum dots (QDs) as the mesoscopic metal oxide layer on ITO-PET substrates. The ITO-PET flexible substrate is treated with oxygen (O2) plasma before creating an efficient barrier layer of Gr, and thereafter as-synthesized ZnO QDs are deposited by spin coating on ITO-PET/Gr thin film. ITO-PET/Gr/ZnO-QDs thin film substrates are finally subjected to APjet treatment using RF power of ~40 W with frequency of ~13.56 MHz, which substantially improves the interfacial properties of the deposited layers. The fabricated ITOPET/Gr/ZnO-QDs(APjet)/CH₃NH₃PbI₃/spiro-MeOTAD/Ag flexible perovskite solar cell obtains the high conversion efficiency of ~9.73% along with high short circuit current JSC) of ~16.8 mA/cm², open circuit voltage (VOC) of ~0.935 V, and high fill factor (FF) of ~0.62. The APjet treatment on ITO-PET/Gr/ZnO QDs thin film enhances the performances and the photocurrent density as compared to other solar cells fabricated without APjet treated ITO-PET/Gr/ZnO QDs thin film. By analyzing the intensitymodulated photocurrent (IMPS)/photovoltage spectroscopy (IMVS), the fabricated flexible perovskite solar cell exhibits a good charge transfer rate and a reduction in the recombination rate. The APjet treatment and the introduction of low-cost Gr barrier layer are promising prospects to approach low cost photovoltaic devices.