Relating Design and Optoelectronic Properties of 1,4-Dihydropyrrolo[3,2-b]pyrroles Bearing Biphenyl Substituents

Understanding the influence of peripheral functionalityon optoelectronicproperties of conjugated materials is an important task for the continueddevelopment of chromophores for myriad applications. Here, & pi;-extended1,4-dihydropyrrolo[3,2-b]pyrrole (DHPP) chromophoreswith varying electron-donating or electron-withdrawing capabilitieswere synthesized via Suzuki cross-coupling reactions, and the influenceof functionality on optoelectronic properties was elucidated. First,chromophores display distinct differences in the UV-vis absorbancespectra measured via UV-vis absorbance spectroscopy in additionto changes in the onset of oxidation measured with cyclic voltammetryand differential pulse voltammetry. Solution oxidation studies foundthat variations in the electron-donating and -withdrawing capabilitiesresult in different absorbance profiles of the radical cations thatcorrespond to quantifiably different colors. In addition to fundamentalinsights into the molecular design of DHPP chromophores and theiroptoelectronic properties, two chromophores display high-contrastelectrochromism, which makes them potentially compelling in electronicdevices. Overall, this study represents the ability to fine-tune theoptoelectronic properties of DHPP chromophores in their neutral andoxidized states and expands the understanding of structure-propertyrelationships that will guide the continued development of DHPP-basedmaterials.

Automated summary

This study synthesized DHPP chromophores with various electron-donating or electron-withdrawing capabilities and investigated their optoelectronic properties. The results showed distinct differences in UV-vis absorbance spectra and oxidation onsets, as well as different absorbance profiles of the radical cations corresponding to different colors. Two chromophores also exhibited high-contrast electrochromism, making them potentially useful in electronic devices.