New Generation of Benzidine Wide‐Gap Conjugated Materials: Solution Processing a Classic Evaporated Scaffold

• Published in: Chemistry : a European journal Vol. 29; no. 40; pp. e202300645 - n/a
• Main Authors: Marqués, Pablo Simón, Gasonoo, Akpeko, Wolfe, Kathryn, Chang, Chia Yun, Welch, Gregory Charles
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 14.07.2023
• Subjects: Alcohols; benzidines; blue emitters; Carbazole; Carbazoles; Chemistry; Electrochemical analysis; Electrochemistry; Electronic equipment; Fluorene; green solvents; molecular engineering; Optical properties; Organic light emitting diodes; Organic semiconductors; slot-die coating; Solubility; Solvents; Substrates; blue emitters; slot-die coating; benzidines; molecular engineering; green solvents
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.202300645

Carbazole‐ and fluorene‐substituted benzidine blocks have been functionalized with two different solubilizing pendant groups, in order to enhance the material's solubility in greener solvents. Preserving the optical and electrochemical properties, the aromatic function and substitution showed an important influence on the solvent affinity, achieving concentrations up to 150 mg/mL in o‐xylenes for the glycol‐containing materials and decent solubility in alcohols for the compounds functionalized with ionic chains. The latter solution proved to be ideal for the preparation of luminescence slot‐die coating film on top of flexible‐substrates up to 33 cm×2 cm. As a proof of concept, the materials have been implemented in different organic electronic devices, highlighting the low turn‐on voltage (4 V) presented by organic light‐emitting diodes (OLEDs), which is comparable with vacuum‐processed devices. A structure‐solubility relationship and a synthetic strategy are disentangled in this manuscript to tailor organic semiconductors and adapt their solubility towards the desired solvent and application. Benzidine‐type wide‐gap materials are designed in order to access green processing techniques, via functionalization with solubilizing pendant groups. Flexible thin films and organic electronic devices are then prepared from low‐toxic solvent such as alcohols or o‐xylenes.