Ester decorated 1,2,4,5-tetraphenylbenzene electrochromic materials with AEE activity, high optical contrast, fast response, and good cycling stability

Multifunctional electrochromic materials are ideal candidates for applications in various commercial fields. In this work, a series of dual-functional materials, 1,2,4,5-tetrakis (4-carboxyphenyl)benzene esters (TCPBEs), were synthesized by decorating 1,2,4,5-tetraphenylbenzene with tetra-esters. TCPBEs exhibited aggregation-induced emission and distinct phenomenon of aggregation-enhanced emission in water/N-methyl pyrrolidone due to their polyphenyl substituted structures and electrochromic properties due to surrounding esters. TCPBEs un-derwent a two-step one-electron reduction process in the electrochemical behavior. The electrochromic devices based on TCPBEs showed good long-term cycling stability (i.e., Hex-TCPBE remained 90% of the initial optical contrast after 2350 cycles), high optical contrast (i.e., Et-TCPBE up to 64.5%) and coloration efficiency (i.e., Hex-TCPBE up to 261 cm2/C), rapid response (< 3 s), and dual colored state. Significant changes in color from colorless bleached state to orange and brown colored states were observed. Each TCPBE demonstrated distinct electrochromic properties because of the electronic effects of different R-substituted ester groups. In general, Et-TCPBE, Hex-TCPBE, and CH3Ph-TCPBE performed better than Bn-TCPBE and CF3Ph-TCPBE. In summary, this study provides a strategy for the design of novel dual-functional electrochromic materials, which have broad application prospects in the field of multifunctional devices.

Automated summary

This study synthesized a series of tetraphenylbenzene esters with aggregation-induced emission and aggregation-enhanced emission properties, and applied them in electrochromic devices, which exhibited good performance. Different substituents affected the electrochromic properties of the materials. This study provides a strategy for designing novel dual-functional electrochromic materials.