Hybrid lead halide perovskites have been revolutionary in the photovoltaic research field, reaching efficiencies comparable with the most established photovoltaic technologies, although they have not yet reached their competitors’ stability. The search for a stable configuration requires the engineering of the charge extraction layers; in this work, molecular doping is used as an efficient method for small molecules and polymers employed as hole transport materials in a planar heterojunction configuration on compact-TiO2. 1 The active layer deposition methodology relies on solvent engineering during the casting process, leading to an ultra-flat, uniform, and thick film ensuring an optimal interface connection with the charge-extracting layer, combined with post-deposition thermal and vacuum treatments, which merge the crystalline domains and cure the defects at the grain boundaries. This method allows obtaining perovskite active layer with superior optical properties. 2 We proved the viability of this approach, obtaining significantly increased performances and reduced hysteresis on compact titania-based devices. We investigated the photovoltaic performance correlated to the hole transport material structure. We have demonstrated that the molecular doping mechanism is more reliable than oxidative doping and have verified that molecular doping in polymeric hole transport materials leads to highly efficient perovskite solar cells, with long-term stability.