Perovskite solar cells are gaining attention due to its tunable bandgap, optical and electrical properties [1][2]. To enable the practical adoption of perovskite solar cells (PSCs), it is crucial to develop a scalable manufacturing process that ensures both high efficiency and long-term stability while adhering to environmentally sustainable practices. Among the scalable processing techniques, liquid-film processing routes attract special attention. Roll to Roll  slot-die coating (R2R-SD) is a scalable and attractive approach for mass manufacturing, enabling the deposition of several functional layers on flexible substrate via low-temperature solution processing [3]. It offers significant advantages in throughput, material utilization and production scalability [4]. R2R process contributes to developing a blueprint and establishing an ecosystem, enabling the expansion of solar cell applications and reducing the cost per square meter. One of the primary challenges in this approach is the choice of solvents, as many conventional options used for charge transport and absorber layer inks are hazardous to both human health and the environment. Given that R2R coating is an open-air process, it is crucial to identify safer solvent alternatives. Additionally, high roll speeds demand precise management of rapid crystallization dynamics to ensure uniform layer formation, preferably under ambient conditions. To tackle these challenges, we have carried out R2R  coating experiments on 30 cm-wide flexible substrates at web speeds of 3 m/min, focusing on optimizing drying techniques to enhance the process efficiency. We have developed opaque and semi-transparent flexible p-i-n perovskite devices with efficiencies up to 13% using R2R compatible perovskite conversion processes. Thermal monostress tests (85 °C) were conducted on these devices and initial stability have been verified after 1000 hours. Additionally, we have explored alternative hole transporting layers (HTL) for R2R processing using non-toxic solvents. We have investigated the impact of processing parameters on device performance, stability, and reproducibility using spin coating and blade coating techniques. We developed p-i-n perovskite devices with achieving ~18% efficiency in spin-coated solar cell stacks. The devices exhibited a V_oc of 1056 mV J_sc of 22 mA/cm², and FF of 78%. First efforts to scale the alternative hole transport layers to R2R-SD coating process resulted in device efficiencies up to 10%. The results demonstrate the potential of R2R processing to enable large-area, flexible, and cost-effective way for commercial applications in photovoltaics.