The development of all solid-state thin-film solar cells has reached a new milestone when the devices made of organometallic lead halide perovskite materials were reported with power conversion efficiency (PCE) exceeding 20 %. The key issue to make a device with a great photovoltaic performance for this kind of solar cells is to control the film morphology of perovskite under different experimental conditions. Varied mesoporous TiO₂ nanostructures were applied to show the morphological effect of the scaffold on the device performance with a mesoscopic heterojuction. Anti-solvent method was applied to improve the morphology and crystallinity of the perovskite films to obtain device performance exceeding PCE 16 %. Varied additives were applied to control the formation morphology of the perovskite nanocrystals with a planar heterojunction. Moreover, we developed a simple drop-casting method via solvent-solvent extraction to grow dense and uniform perovskite nanocrystals at room temperature for carbon-based mesoscopic solar cells free of an organic hole-transport layer. The CH₃NH₃PbI₃/ N-methyl-2-pyrrolidone (NMP) precursor solution (40 %) was first dripped onto a substrate with film configuration TiO₂/Al₂O₃/C and infiltrated at 70 °C for 10 min. The perovskite substrate was next immersed in a bath of diethyl ether at 25 °C for 30 min. Third, the solvent-extracted substrate was stored in a dry box (humidity 50 %) at 25 °C for at least 100 h to complete the crystal growth. The device performance attained an efficiency 12.3 % of power conversion (PCE), which is significantly greater than that of DMF (6.3 %) and NMP (8.3 %) devices using traditional thermal annealing. For tin-rich perovskite, we designed and synthesized alloyed Sn-Pb mixed halide perovskites by dipping the precursor solutions on the mesoporous films with the TiO₂/Al₂O₃/C configuration to form solar cells free of organic HTM. When 30 mol% of SnF₂ additive was added in the tin-rich mix halide precursor solution, the device performance was improved from PCE 2.2 % (without SnF₂) to PCE 4.3 % (with SnF₂) with little effect of hysteresis; the short-circuit current density J_SC has reached a remarkable level with 23.33±0.73 mA cm^-2.