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In dye sensitized solar cells (DSSC), the counter electrode (CE) plays a significant role in electro catalytic reaction in redox region to achieve maximum power conversion efficiency (PCE) of the DSSC. The graphene oxide (GO) is synthesized by Hummer's method and converted to reduced graphene oxide (RGO) by thermal method. The effect of binders such as NMP, PVP, and nafion for RGO are investigated. The field emission scanning electron microscope (FESEM) of RGO shows the fine layers like structure. The surface area of the RGO is found to be 110.16 m2 g−1 by Brunauer–Emmett–Teller (BET) method and pore volume 0.5182 cm3 g−1 of RGO by Barrett–Joyner–Halenda (BJH) method. The Raman spectra is used to analyze the structural defects and changes of GO and RGO. The crystallite size of GO is 18.6 nm, and RGO is 20.9 nm calculated from the Raman spectrum. For analyzing the electro catalytic properties of the RGO/NMP/PVP, RGO/NMP, and RGO/nafion based CE materials cyclic voltammetry is performed and its maximum current density was measured. The composition of RGO/NMP/PVP based CE exhibits better electro‐catalytic properties when compared to other RGO/NMP and RGO/nafion based counter electrodes. Maximum PCE exhibited by RGO/NMP/PVP CE based DSSC is 5.8%.

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The efficiency of perovskite devices is depending on the crystallization process with a controlled microstructure. Perovskite precursors with polymer additive significantly improve the perovskite film crystallinity, large grain boundaries, serve as passivating defect sites yielding increased power conversion efficiency (PCE). In this study, we improved the hole-transport free carbon-based perovskite solar cells by using polymer additive to passivate the perovskite grains with large size crystal and assist to grow with the preferred orientation of the polycrystalline perovskite layer. The polymer additive systematically alters the morphology of the perovskite films. The perovskite with polymer additives exhibited reduced trap density, which could enhance the open-circuit voltage.The fluoro-polymer as an additive into perovskite layer facilitated a hydrogen bond with organic cation to form H-F bond, which could prevent degradation from moisture. The solar device with 5 wt% PVDF-HFP additives achieved $14% improvement in open-circuit voltage and yielded a PCE of 11.11%. Moreover, the shelf-life of the solar device retains 86% from its original efficiency with a period of 30 days (stored under ambient condition, 60%-70% humidity). It is revealing that the fluoro-polymer enhances the passivation of perovskite grains and gives a hope in perovskite photovoltaics.