The effect of solution temperature on the solution-state aggregation behavior was further investigated by using temperature-dependent SAXS and UV-Vis spectroscopy. From the temperature-dependent SAXS solution experiment for PM7 (Fig. ), we observe that the Guinier knee region, which corresponds to the radius of the large fibrillar aggregates, completely disappears when the solution temperature is increased. Instead, we observe a Porod region at low Q with a slope close to -2. This indicates that the fibrillar aggregates are dissolved with increasing temperature while the network-like small aggregates in solution are preserved. The temperature-dependent solution UV-Vis of PM7 (Fig. ) also demonstrates that the vibronic fine structure decreases with increasing temperature, suggesting an increase in backbone disorder which may be responsible for breaking down the fibrillar aggregates. On the other hand, the temperature-dependent SAXS for PM7 D1 and D2 solution (Fig. and) show only the structure factor peak intensity decrease without any substantial changes. This result indicates that the side-chain interactions of the PM7 D1 and D2 polymer are reduced with increasing temperature in solution while the network structure is still maintained. The effect of temperature, however, seems to influence the backbone conformation of PM7 D1 and D2 rather than their aggregate structures. The temperature-dependent solution UV-Vis (Fig. and) indicates that the absorption onsets of PM7 D1 and D2 are significantly blue shifted due to further twisting of the backbone, which could be attributed to the anti and syn conformation switch enabled by their low energy barriers as previously discussed (Fig. ). These observations suggest that, regardless of backbone disorder of PM7 D1 and D2, the polymer networklike structure can be maintained against temperature change, while fibrillar aggregates are highly sensitive to temperature induced backbone conformation change. It is well-known that carrying out active film formation by spin-coating under an inert atmosphere using 1, 8-diiodooctane (DIO) as an additive can provide high performance solar cells, and PM7:ITIC-4F pair has been reported to have a PCE up to 14%. In this work, we employed meniscus-guided coating in air without additives to demonstrate compatibility with scalable largearea coating techniques under more practical conditions. Unlike spin coating, in which the spin speed of the substrate is the only processing parameter, the blade coating process involves several processing parameters such as coating speed, substrate temperature, and blade angle which all influence the film thickness, uniformity, and device performance of OSCs. The objective is to obtain uniform films with an optimal film thickness of around 80-100 nm under various substrate temperatures to investigate the effect of substrate temperature on the solid-state morphology and device performance of OSCs. Therefore, we first determined how each of the processing parameters affect the film thickness and uniformity. To demonstrate how the film thickness and uniformity are affected by the processing parameters, we take PM7:ITIC-4F film deposition as an example to show the thickness as a function of coating speed relationship by (1) varying the substrate temperatures while keeping the blade angle constant (Fig. ) and ( ) varying the blade angles while keeping the substrate temperature constant (Fig. ). As seen from Fig. , when the substrate temperature is 25 °C with a blade angle of 7°, the film thickness decreases as the coating speed increases from 0.01 mm/s to ~ 0.5 mm/s. This inverse relationship between the coating speed and film thickness corresponds to the evaporation regime where the solution evaporation rate governs the relationship between the final film thickness and the coating speed. In this regime, we observe poor film uniformity (Fig. ) due to stick-and-slip meniscus instability caused by a competition between pinning and depinning forces at the contact line. On the other hand, in the Landau-Levich (LL) regime where the film thickness increases with coating speed, the deposited films are more uniform which is desirable to reduce device-to-device performance variations (Fig. ). Although the films are more uniform in the LL regime, the film thickness changes substantially when the substrate temperature is increased from 25 °C to 105 °C at a blade angle of 7° (the red plot in Fig. ). In fact, we can see that the entire thickness versus coating speed relationship (both evaporation and LL regime) shifts to the right due to an increased evaporation rate and the change in the physical properties of the solution at an elevated temperature. Due to this shift, the film thickness is significantly reduced in the LL regime from ~100 to ~50nm when increasing the substrate temperature from 25 to 100°C while maintaining the same coating speed of 5 mm/s, as indicated by the dashed line in Fig. . To increase the film thickness without changing the concentration of the solution or the coating speed at a substrate temperature of 105 °C, we increased the blade angle from 7° to 45° which shifted the entire curve upwards as shown in Fig. resulting in the final thickness of ~ 100 nm at 5 mm/s as indicated by the dashed line. We attribute this upward shift to an increased solution supply from the back meniscus to the front where the solution evaporation takes place, as increased tilt angle reduces the back meniscus pressure. This increased solution supply from the back meniscus increases the film thickness in both regimes allowing us to vary the film thickness at any substrate temperature without changing the solution concentration or the coating speed.