In this work, we fabricated four diphenylcyclopropenone (DPCP) crystals, which involved various molecular interactions encoded in individual molecular structures 1-4. On the basis of crystalline structural analysis and photoresponsive characterization of the resultant single-crystal microribbons 1-4, we demonstrated that the magnitude of molecular interactions could effectively control the quantum chain reaction and the photoresponsive property of the DPCP crystals. The microribbons 1 and 2 having weak molecular interactions exhibited an efficient chain reaction and large mechanical photoresponses (i.e., photomelting and photodeforming), whereas the microribbons 3 and 4 with strong molecular interactions exhibited no chain reaction and mechanical morphology change. Our work presented a new way to achieve molecular crystals with enhanced mechanical photoresponses.