[b] Crystals of compound 6 was not measured due to small crystal size. increments: from 26.8 mN to 34.4 mN (an increase of 7.6 mN), and then to 37.0 mN (an increase of only 2.6 mN). This diminishing rate of improvement, coupled with the fact that the last three maximum values were achieved using crystals of compound 3 under similar conditions, strongly suggests that the optimization was approaching the global maximum within our parameter space. The crystals of compound 3 were selected the most in the optimization process (Figure ). While continuing the experiments might yield marginally higher forces, the decreasing magnitude of improvements indicated that we had likely identified the region of optimal conditions. This study compares the force values achieved with those from previous research. The force of photomechanical crystals has previously been evaluated by the displacement of objects with known weights. The force achieved by photomechanical crystals was typically μN-mN order, around 10 mN at maximum . While our initial data also showed this value, by actively seeking to maximize the force, we achieved a greater force than previously known. On the other hand, the force density, which is the force divided by the crystal volume, reached a maximum of 1.7×10 8 N/m 3 , which is comparable to existing photomechanical crystals (10 7 -10 9 ). Force density is a value that cancels out size effects, indicating that the light absorption properties and intermolecular interactions of our crystals are similar to those of other photomechanical crystals. Conversely, the significance of this study lies in demonstrating that larger forces can be achieved by sampling experimental conditions. The success of Bayesian optimization is evidenced by its ability to identify optimal combinations of crystal properties and sizes, rather than simply selecting the largest available crystals (Figure ). If larger crystal volume automatically corresponded to greater force generation, a simple maximization of crystal sizes would suffice. However, the optimization process converged on specific combinations of crystal properties and dimensions, indicating that there exists an optimal balance between crystal characteristics and size for maximizing the blocking force.