Biphenyl Dicarboxylic-Based Ni-IRMOF-74 Film for Fast-Switching and High-Stability Electrochromism

Metal–organic frameworks (MOFs) are promising electrochromic materials known for their rapid response speed and ability to transition through multiple colors. However, typical MOF films suffer from slow response times and poor stability due to inappropriate pore sizes, weak substrate interaction, and limited bond reversibility. This study addresses these challenges by modifying F-doped SnO2 with 4-mercaptobenzoic acid and fabricating Ni-IRMOF-74@MBA films using 3,3′-dihydroxy-4,4′-biphenyldicarboxylic acid. The optimized film exhibits a rapid response (1.9 s/2.0 s), high efficiency (331.0 cm2 C–1), and favorable stability (95.7% retention after 4500 cycles), transitioning from transparent to green at 0.8 V and deep-brown at 1.6 V due to Li+ interaction with the ligand. The resulting electrochromic device shows improved response (2.3 s/7.9 s) and stability (85% retention after 1200 cycles). This work presents a significant advancement in developing MOFs for electrochromic applications.