Predicting Emission in Substituted N‐Alkyl Carbazoles to Create New Mechanoluminescent Molecules

Unsubstituted N-alkyl carbazoles have been experimentally demonstrated to exhibit renewable mechanoluminescence. This computational study examines the effectiveness of using electron-donating or withdrawing substituents for tuning the expected emission energies of N-alkyl carbazoles.

Abstract

Mechanoluminescence (ML) is the emission of light caused by mechanical stresses on solid, usually crystalline substances. Recently, it has been observed that a specific class of organic crystals, N-alkyl carbazoles, have both low melting points and high proclivity for self-assembly, making them easily renewable for long-term device applications. To develop new carbazole-based ML materials for device applications, it is necessary to be able to tune their emission to desirable wavelengths. In this study, we computationally investigated using chemical substituents with electron-withdrawing/donating character to tune the emission wavelength of N-alkyl carbazoles. We find that strongly electron-withdrawing substituent groups can be used as one controlling factor for tuning emission wavelengths for N-alkyl carbazoles. This finding provides materials scientists with a new family of derivatives for designing effective organic materials with desirable ML emission properties.

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